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1 | =head1 NAME |
2 | |
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3 | perldelta - what's new for perl v5.6.0 |
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4 | |
5 | =head1 DESCRIPTION |
6 | |
7 | This document describes differences between the 5.005 release and this one. |
8 | |
9 | =head1 Incompatible Changes |
10 | |
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11 | =head2 Perl Source Incompatibilities |
12 | |
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13 | Beware that any new warnings that have been added or old ones |
14 | that have been enhanced are B<not> considered incompatible changes. |
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15 | |
16 | Since all new warnings must be explicitly requested via the C<-w> |
17 | switch or the C<warnings> pragma, it is ultimately the programmer's |
18 | responsibility to ensure that warnings are enabled judiciously. |
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19 | |
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20 | =over 4 |
21 | |
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22 | =item CHECK is a new keyword |
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23 | |
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24 | In addition to C<BEGIN>, C<INIT>, C<END>, C<DESTROY> and C<AUTOLOAD>, |
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25 | subroutines named C<CHECK> are now special. These are queued up during |
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26 | compilation and behave similar to END blocks, except they are called at |
27 | the end of compilation rather than at the end of execution. They cannot |
28 | be called directly. |
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29 | |
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30 | =item Treatment of list slices of undef has changed |
31 | |
32 | When taking a slice of a literal list (as opposed to a slice of |
33 | an array or hash), Perl used to return an empty list if the |
34 | result happened to be composed of all undef values. |
35 | |
36 | The new behavior is to produce an empty list if (and only if) |
37 | the original list was empty. Consider the following example: |
38 | |
39 | @a = (1,undef,undef,2)[2,1,2]; |
40 | |
41 | The old behavior would have resulted in @a having no elements. |
42 | The new behavior ensures it has three undefined elements. |
43 | |
44 | Note in particular that the behavior of slices of the following |
45 | cases remains unchanged: |
46 | |
47 | @a = ()[1,2]; |
48 | @a = (getpwent)[7,0]; |
49 | @a = (anything_returning_empty_list())[2,1,2]; |
50 | @a = @b[2,1,2]; |
51 | @a = @c{'a','b','c'}; |
52 | |
53 | See L<perldata>. |
54 | |
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55 | =head2 Perl's version numbering has changed |
56 | |
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57 | Beginning with Perl version 5.6.0, the version number convention has been |
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58 | changed to a "dotted integer" scheme that is more commonly found in open |
59 | source projects. |
60 | |
61 | Maintenance versions of v5.6.0 will be released as v5.6.1, v5.6.2 etc. |
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62 | The next development series following v5.6.0 will be numbered v5.7.x, |
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63 | beginning with v5.7.0, and the next major production release following |
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64 | v5.6.0 will be v5.8.0. |
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65 | |
66 | The English module now sets $PERL_VERSION to $^V (a string value) rather |
67 | than C<$]> (a numeric value). (This is a potential incompatibility. |
68 | Send us a report via perlbug if you are affected by this.) |
69 | |
70 | The v1.2.3 syntax is also now legal in Perl. |
71 | See L<Support for strings represented as a vector of ordinals> for more on that. |
72 | |
73 | To cope with the new versioning system's use of at least three significant |
74 | digits for each version component, the method used for incrementing the |
75 | subversion number has also changed slightly. We assume that versions older |
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76 | than v5.6.0 have been incrementing the subversion component in multiples of |
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77 | 10. Versions after v5.6.0 will increment them by 1. Thus, using the new |
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78 | notation, 5.005_03 is the "same" as v5.5.30, and the first maintenance |
79 | version following v5.6.0 will be v5.6.1 (which should be read as being |
80 | equivalent to a floating point value of 5.006_001 in the older format, |
81 | stored in C<$]>). |
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82 | |
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83 | =item Literals of the form C<1.2.3> parse differently |
84 | |
85 | Previously, numeric literals with more than one dot in them were |
86 | interpreted as a floating point number concatenated with one or more |
87 | numbers. Such "numbers" are now parsed as strings composed of the |
88 | specified ordinals. |
89 | |
90 | For example, C<print 97.98.99> used to output C<97.9899> in earlier |
91 | versions, but now prints C<abc>. |
92 | |
93 | See L<Support for strings represented as a vector of ordinals> below. |
94 | |
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95 | =item Possibly changed pseudo-random number generator |
96 | |
97 | In 5.005_0x and earlier, perl's rand() function used the C library |
98 | rand(3) function. As of 5.005_52, Configure tests for drand48(), |
99 | random(), and rand() (in that order) and picks the first one it finds. |
100 | Perl programs that depend on reproducing a specific set of pseudo-random |
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101 | numbers will now likely produce different output. You can use |
102 | C<sh Configure -Drandfunc=rand> to obtain the old behavior. |
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103 | |
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104 | =item Hashing function for hash keys has changed |
105 | |
106 | Perl hashes are not order preserving. The apparently random order |
107 | encountered when iterating on the contents of a hash is determined |
108 | by the hashing algorithm used. To improve the distribution of lower |
109 | bits in the hashed value, the algorithm has changed slightly as of |
110 | 5.005_52. When iterating over hashes, this may yield a random order |
111 | that is B<different> from that of previous versions. |
112 | |
113 | =item C<undef> fails on read only values |
114 | |
115 | Using the C<undef> operator on a readonly value (such as $1) has |
116 | the same effect as assigning C<undef> to the readonly value--it |
117 | throws an exception. |
118 | |
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119 | =item Close-on-exec bit may be set on pipe and socket handles |
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120 | |
121 | On systems that support a close-on-exec flag on filehandles, the |
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122 | flag will be set for any handles created by pipe(), socketpair(), |
123 | socket(), and accept(), if that is warranted by the value of $^F |
124 | that may be in effect. Earlier versions neglected to set the flag |
125 | for handles created with these operators. See L<perlfunc/pipe>, |
126 | L<perlfunc/socketpair>, L<perlfunc/socket>, L<perlfunc/accept>, |
127 | and L<perlvar/$^F>. |
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128 | |
129 | =item Writing C<"$$1"> to mean C<"${$}1"> is unsupported |
130 | |
131 | Perl 5.004 deprecated the interpretation of C<$$1> and |
132 | similar within interpolated strings to mean C<$$ . "1">, |
133 | but still allowed it. |
134 | |
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135 | In Perl 5.6.0 and later, C<"$$1"> always means C<"${$1}">. |
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136 | |
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137 | =item delete(), values() and C<\(%h)> operate on aliases to values, not copies |
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138 | |
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139 | delete(), each(), values() and hashes in a list context return the actual |
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140 | values in the hash, instead of copies (as they used to in earlier |
141 | versions). Typical idioms for using these constructs copy the |
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142 | returned values, but this can make a significant difference when |
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143 | creating references to the returned values. |
144 | |
145 | Keys in the hash are still returned as copies when iterating on |
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146 | a hash. |
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147 | |
148 | =item vec(EXPR,OFFSET,BITS) enforces powers-of-two BITS |
149 | |
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150 | vec() generates a run-time error if the BITS argument is not |
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151 | a valid power-of-two integer. |
152 | |
153 | =item Text of some diagnostic output has changed |
154 | |
155 | Most references to internal Perl operations in diagnostics |
156 | have been changed to be more descriptive. This may be an |
157 | issue for programs that may incorrectly rely on the exact |
158 | text of diagnostics for proper functioning. |
159 | |
160 | =item C<%@> has been removed |
161 | |
162 | The undocumented special variable C<%@> that used to accumulate |
163 | "background" errors (such as those that happen in DESTROY()) |
164 | has been removed, because it could potentially result in memory |
165 | leaks. |
166 | |
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167 | =item Parenthesized not() behaves like a list operator |
168 | |
169 | The C<not> operator now falls under the "if it looks like a function, |
170 | it behaves like a function" rule. |
171 | |
172 | As a result, the parenthesized form can be used with C<grep> and C<map>. |
173 | The following construct used to be a syntax error before, but it works |
174 | as expected now: |
175 | |
176 | grep not($_), @things; |
177 | |
178 | On the other hand, using C<not> with a literal list slice may not |
179 | work. The following previously allowed construct: |
180 | |
181 | print not (1,2,3)[0]; |
182 | |
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183 | needs to be written with additional parentheses now: |
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184 | |
185 | print not((1,2,3)[0]); |
186 | |
187 | The behavior remains unaffected when C<not> is not followed by parentheses. |
188 | |
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189 | =item Semantics of bareword prototype C<(*)> have changed |
190 | |
191 | Arguments prototyped as C<*> will now be visible within the subroutine |
192 | as either a simple scalar or as a reference to a typeglob. Perl 5.005 |
193 | always coerced simple scalar arguments to a typeglob, which wasn't useful |
194 | in situations where the subroutine must distinguish between a simple |
195 | scalar and a typeglob. See L<perlsub/Prototypes>. |
196 | |
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197 | =head2 On 64-bit platforms the semantics of bit operators have changed |
198 | |
199 | If your platform is either natively 64-bit or your Perl has been |
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200 | configured to used 64-bit integers, i.e., $Config{ivsize} is 8, |
201 | be warned that the semantics of all the bitwise numeric operators |
202 | (& | ^ ~ << >>) have been changed. These operators used to strictly |
203 | operate on the lower 32 bits of integers, but now operate over the |
204 | entire width of native integers. In particular, note that unary C<~> |
205 | will produce different results on platforms that have different |
206 | $Config{ivsize}. For portability, be sure to mask off the excess bits |
207 | in the result of unary C<~>, e.g., C<~$x & 0xffffffff>. |
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208 | |
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209 | =back |
210 | |
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211 | =head2 C Source Incompatibilities |
212 | |
213 | =over 4 |
214 | |
215 | =item C<PERL_POLLUTE> |
216 | |
217 | Release 5.005 grandfathered old global symbol names by providing preprocessor |
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218 | macros for extension source compatibility. As of release 5.6.0, these |
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219 | preprocessor definitions are not available by default. You need to explicitly |
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220 | compile perl with C<-DPERL_POLLUTE> to get these definitions. For |
221 | extensions still using the old symbols, this option can be |
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222 | specified via MakeMaker: |
223 | |
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224 | perl Makefile.PL POLLUTE=1 |
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225 | |
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226 | =item C<PERL_IMPLICIT_CONTEXT> |
227 | |
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228 | NOTE: PERL_IMPLICIT_CONTEXT is automatically enabled whenever Perl is built |
229 | with one of -Dusethreads, -Dusemultiplicity, or both. It is not |
230 | intended to be enabled by users at this time. |
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231 | |
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232 | This new build option provides a set of macros for all API functions |
233 | such that an implicit interpreter/thread context argument is passed to |
234 | every API function. As a result of this, something like C<sv_setsv(foo,bar)> |
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235 | amounts to a macro invocation that actually translates to something like |
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236 | C<Perl_sv_setsv(my_perl,foo,bar)>. While this is generally expected |
237 | to not have any significant source compatibility issues, the difference |
238 | between a macro and a real function call will need to be considered. |
239 | |
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240 | This means that there B<is> a source compatibility issue as a result of |
241 | this if your extensions attempt to use pointers to any of the Perl API |
242 | functions. |
243 | |
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244 | Note that the above issue is not relevant to the default build of |
245 | Perl, whose interfaces continue to match those of prior versions |
246 | (but subject to the other options described here). |
247 | |
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248 | See L<perlguts/"The Perl API"> for detailed information on the |
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249 | ramifications of building Perl with this option. |
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250 | |
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251 | =item C<PERL_POLLUTE_MALLOC> |
252 | |
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253 | Enabling Perl's malloc in release 5.005 and earlier caused the namespace of |
254 | the system's malloc family of functions to be usurped by the Perl versions, |
255 | since by default they used the same names. Besides causing problems on |
256 | platforms that do not allow these functions to be cleanly replaced, this |
257 | also meant that the system versions could not be called in programs that |
258 | used Perl's malloc. Previous versions of Perl have allowed this behaviour |
259 | to be suppressed with the HIDEMYMALLOC and EMBEDMYMALLOC preprocessor |
260 | definitions. |
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261 | |
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262 | As of release 5.6.0, Perl's malloc family of functions have default names |
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263 | distinct from the system versions. You need to explicitly compile perl with |
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264 | C<-DPERL_POLLUTE_MALLOC> to get the older behaviour. HIDEMYMALLOC |
265 | and EMBEDMYMALLOC have no effect, since the behaviour they enabled is now |
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266 | the default. |
267 | |
268 | Note that these functions do B<not> constitute Perl's memory allocation API. |
269 | See L<perlguts/"Memory Allocation"> for further information about that. |
270 | |
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271 | =back |
272 | |
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273 | =head2 Compatible C Source API Changes |
274 | |
275 | =over |
276 | |
277 | =item C<PATCHLEVEL> is now C<PERL_VERSION> |
278 | |
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279 | The cpp macros C<PERL_REVISION>, C<PERL_VERSION>, and C<PERL_SUBVERSION> |
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280 | are now available by default from perl.h, and reflect the base revision, |
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281 | patchlevel, and subversion respectively. C<PERL_REVISION> had no |
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282 | prior equivalent, while C<PERL_VERSION> and C<PERL_SUBVERSION> were |
283 | previously available as C<PATCHLEVEL> and C<SUBVERSION>. |
284 | |
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285 | The new names cause less pollution of the B<cpp> namespace and reflect what |
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286 | the numbers have come to stand for in common practice. For compatibility, |
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287 | the old names are still supported when F<patchlevel.h> is explicitly |
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288 | included (as required before), so there is no source incompatibility |
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289 | from the change. |
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290 | |
291 | =back |
292 | |
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293 | =head2 Binary Incompatibilities |
294 | |
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295 | In general, the default build of this release is expected to be binary |
296 | compatible for extensions built with the 5.005 release or its maintenance |
297 | versions. However, specific platforms may have broken binary compatibility |
298 | due to changes in the defaults used in hints files. Therefore, please be |
299 | sure to always check the platform-specific README files for any notes to |
300 | the contrary. |
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301 | |
302 | The usethreads or usemultiplicity builds are B<not> binary compatible |
303 | with the corresponding builds in 5.005. |
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304 | |
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305 | On platforms that require an explicit list of exports (AIX, OS/2 and Windows, |
306 | among others), purely internal symbols such as parser functions and the |
307 | run time opcodes are not exported by default. Perl 5.005 used to export |
308 | all functions irrespective of whether they were considered part of the |
309 | public API or not. |
310 | |
311 | For the full list of public API functions, see L<perlapi>. |
312 | |
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313 | =head1 Installation and Configuration Improvements |
314 | |
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315 | =head2 -Dusethreads means something different |
316 | |
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317 | WARNING: Support for threads continues to be an experimental feature. |
318 | Interfaces and implementation are subject to sudden and drastic changes. |
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319 | |
320 | The -Dusethreads flag now enables the experimental interpreter-based thread |
321 | support by default. To get the flavor of experimental threads that was in |
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322 | 5.005 instead, you need to run Configure with "-Dusethreads -Duse5005threads". |
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323 | |
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324 | As of v5.6.0, interpreter-threads support is still lacking a way to |
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325 | create new threads from Perl (i.e., C<use Thread;> will not work with |
326 | interpreter threads). C<use Thread;> continues to be available when you |
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327 | specify the -Duse5005threads option to Configure, bugs and all. |
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328 | |
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329 | =head2 New Configure flags |
330 | |
331 | The following new flags may be enabled on the Configure command line |
332 | by running Configure with C<-Dflag>. |
333 | |
334 | usemultiplicity |
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335 | usethreads useithreads (new interpreter threads: no Perl API yet) |
336 | usethreads use5005threads (threads as they were in 5.005) |
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337 | |
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338 | use64bitint (equal to now deprecated 'use64bits') |
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339 | use64bitall |
340 | |
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341 | uselongdouble |
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342 | usemorebits |
343 | uselargefiles |
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344 | usesocks (only SOCKS v5 supported) |
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345 | |
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346 | =head2 Threadedness and 64-bitness now more daring |
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347 | |
348 | The Configure options enabling the use of threads and the use of |
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349 | 64-bitness are now more daring in the sense that they no more have an |
350 | explicit list of operating systems of known threads/64-bit |
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351 | capabilities. In other words: if your operating system has the |
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352 | necessary APIs and datatypes, you should be able just to go ahead and |
353 | use them, for threads by Configure -Dusethreads, and for 64 bits |
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354 | either explicitly by Configure -Duse64bitint or implicitly if your |
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355 | system has 64-bit wide datatypes. See also L<"64-bit support">. |
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356 | |
357 | =head2 Long Doubles |
358 | |
359 | Some platforms have "long doubles", floating point numbers of even |
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360 | larger range than ordinary "doubles". To enable using long doubles for |
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361 | Perl's scalars, use -Duselongdouble. |
362 | |
363 | =head2 -Dusemorebits |
364 | |
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365 | You can enable both -Duse64bitint and -Duselongdouble with -Dusemorebits. |
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366 | See also L<"64-bit support">. |
367 | |
368 | =head2 -Duselargefiles |
369 | |
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370 | Some platforms support system APIs that are capable of handling large files |
371 | (typically, files larger than two gigabytes). Perl will try to use these |
372 | APIs if you ask for -Duselargefiles. |
373 | |
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374 | See L<"Large file support"> for more information. |
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375 | |
376 | =head2 installusrbinperl |
377 | |
378 | You can use "Configure -Uinstallusrbinperl" which causes installperl |
379 | to skip installing perl also as /usr/bin/perl. This is useful if you |
380 | prefer not to modify /usr/bin for some reason or another but harmful |
381 | because many scripts assume to find Perl in /usr/bin/perl. |
382 | |
383 | =head2 SOCKS support |
384 | |
385 | You can use "Configure -Dusesocks" which causes Perl to probe |
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386 | for the SOCKS proxy protocol library (v5, not v4). For more information |
387 | on SOCKS, see: |
388 | |
389 | http://www.socks.nec.com/ |
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390 | |
391 | =head2 C<-A> flag |
392 | |
393 | You can "post-edit" the Configure variables using the Configure C<-A> |
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394 | switch. The editing happens immediately after the platform specific |
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395 | hints files have been processed but before the actual configuration |
396 | process starts. Run C<Configure -h> to find out the full C<-A> syntax. |
397 | |
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398 | =head2 Enhanced Installation Directories |
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399 | |
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400 | The installation structure has been enriched to improve the support |
401 | for maintaining multiple versions of perl, to provide locations for |
402 | vendor-supplied modules, scripts, and manpages, and to ease maintenance |
403 | of locally-added modules, scripts, and manpages. See the section on |
404 | Installation Directories in the INSTALL file for complete details. |
405 | For most users building and installing from source, the defaults should |
406 | be fine. |
407 | |
408 | If you previously used C<Configure -Dsitelib> or C<-Dsitearch> to set |
409 | special values for library directories, you might wish to consider using |
410 | the new C<-Dsiteprefix> setting instead. Also, if you wish to re-use a |
411 | config.sh file from an earlier version of perl, you should be sure to |
412 | check that Configure makes sensible choices for the new directories. |
413 | See INSTALL for complete details. |
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414 | |
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415 | =head1 Core Changes |
416 | |
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417 | =head2 Unicode and UTF-8 support |
418 | |
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419 | WARNING: This is an experimental feature. Implementation details are |
420 | subject to change. |
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421 | |
422 | Perl now uses UTF-8 as its internal representation for character |
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423 | strings. The C<utf8> and C<bytes> pragmas are used to control this support |
424 | in the current lexical scope. See L<perlunicode>, L<utf8> and L<bytes> for |
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425 | more information. |
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426 | |
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427 | =head2 Interpreter cloning, threads, and concurrency |
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428 | |
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429 | WARNING: This is an experimental feature. Implementation details are |
430 | subject to change. |
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431 | |
432 | Perl 5.005_63 introduces the beginnings of support for running multiple |
433 | interpreters concurrently in different threads. In conjunction with |
434 | the perl_clone() API call, which can be used to selectively duplicate |
435 | the state of any given interpreter, it is possible to compile a |
436 | piece of code once in an interpreter, clone that interpreter |
437 | one or more times, and run all the resulting interpreters in distinct |
438 | threads. |
439 | |
440 | On Windows, this feature is used to emulate fork() at the interpreter |
441 | level. See L<perlfork>. |
442 | |
443 | This feature is still in evolution. It is eventually meant to be used |
444 | to selectively clone a subroutine and data reachable from that |
445 | subroutine in a separate interpreter and run the cloned subroutine |
446 | in a separate thread. Since there is no shared data between the |
447 | interpreters, little or no locking will be needed (unless parts of |
448 | the symbol table are explicitly shared). This is obviously intended |
449 | to be an easy-to-use replacement for the existing threads support. |
450 | |
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451 | Support for cloning interpreters and interpreter concurrency can be |
452 | enabled using the -Dusethreads Configure option (see win32/Makefile for |
453 | how to enable it on Windows.) The resulting perl executable will be |
454 | functionally identical to one that was built with -Dmultiplicity, but |
455 | the perl_clone() API call will only be available in the former. |
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456 | |
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457 | -Dusethreads enables the cpp macro USE_ITHREADS by default, which in turn |
458 | enables Perl source code changes that provide a clear separation between |
459 | the op tree and the data it operates with. The former is immutable, and |
460 | can therefore be shared between an interpreter and all of its clones, |
461 | while the latter is considered local to each interpreter, and is therefore |
462 | copied for each clone. |
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463 | |
464 | Note that building Perl with the -Dusemultiplicity Configure option |
465 | is adequate if you wish to run multiple B<independent> interpreters |
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466 | concurrently in different threads. -Dusethreads only provides the |
467 | additional functionality of the perl_clone() API call and other |
468 | support for running B<cloned> interpreters concurrently. |
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469 | |
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470 | =head2 Lexically scoped warning categories |
471 | |
472 | You can now control the granularity of warnings emitted by perl at a finer |
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473 | level using the C<use warnings> pragma. See L<warnings> and L<perllexwarn> |
0453d815 |
474 | for details. |
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475 | |
a5222a85 |
476 | =head2 Lvalue subroutines |
477 | |
642f9deb |
478 | WARNING: This is an experimental feature. Details are subject to change. |
a5222a85 |
479 | |
21bad921 |
480 | Subroutines can now return modifiable lvalues. |
481 | See L<perlsub/"Lvalue subroutines">. |
a5222a85 |
482 | |
483 | =head2 "our" declarations |
484 | |
485 | An "our" declaration introduces a value that can be best understood |
486 | as a lexically scoped symbolic alias to a global variable in the |
16070b82 |
487 | package that was current where the variable was declared. This is |
488 | mostly useful as an alternative to the C<vars> pragma, but also provides |
489 | the opportunity to introduce typing and other attributes for such |
490 | variables. See L<perlfunc/our>. |
491 | |
44dcb63b |
492 | =head2 Support for strings represented as a vector of ordinals |
16070b82 |
493 | |
dd629d5b |
494 | Literals of the form C<v1.2.3.4> are now parsed as a string composed of |
44dcb63b |
495 | of characters with the specified ordinals. This is an alternative, more |
496 | readable way to construct (possibly unicode) strings instead of |
dd629d5b |
497 | interpolating characters, as in C<"\x{1}\x{2}\x{3}\x{4}">. The leading |
498 | C<v> may be omitted if there are more than two ordinals, so C<1.2.3> is |
499 | parsed the same as C<v1.2.3>. |
16070b82 |
500 | |
44dcb63b |
501 | Strings written in this form are also useful to represent version "numbers". |
502 | It is easy to compare such version "numbers" (which are really just plain |
503 | strings) using any of the usual string comparison operators C<eq>, C<ne>, |
504 | C<lt>, C<gt>, etc., or perform bitwise string operations on them using C<|>, |
505 | C<&>, etc. |
16070b82 |
506 | |
507 | In conjunction with the new C<$^V> magic variable (which contains |
44dcb63b |
508 | the perl version as a string), such literals can be used as a readable way |
509 | to check if you're running a particular version of Perl: |
16070b82 |
510 | |
44dcb63b |
511 | # this will parse in older versions of Perl also |
642f9deb |
512 | if ($^V and $^V gt v5.6.0) { |
44dcb63b |
513 | # new features supported |
16070b82 |
514 | } |
515 | |
44dcb63b |
516 | C<require> and C<use> also have some special magic to support such literals. |
517 | They will be interpreted as a version rather than as a module name: |
16070b82 |
518 | |
b22c7a20 |
519 | require v5.6.0; # croak if $^V lt v5.6.0 |
520 | use v5.6.0; # same, but croaks at compile-time |
a5222a85 |
521 | |
dd629d5b |
522 | Alternatively, the C<v> may be omitted if there is more than one dot: |
523 | |
524 | require 5.6.0; |
525 | use 5.6.0; |
526 | |
44dcb63b |
527 | Also, C<sprintf> and C<printf> support the Perl-specific format flag C<%v> |
b22c7a20 |
528 | to print ordinals of characters in arbitrary strings: |
1761cee5 |
529 | |
b22c7a20 |
530 | printf "v%vd", $^V; # prints current version, such as "v5.5.650" |
531 | printf "%*vX", ":", $addr; # formats IPv6 address |
dd629d5b |
532 | printf "%*vb", " ", $bits; # displays bitstring |
1761cee5 |
533 | |
191d61a7 |
534 | See L<perldata/"Scalar value constructors"> for additional information. |
44dcb63b |
535 | |
a5222a85 |
536 | =head2 Weak references |
537 | |
642f9deb |
538 | WARNING: This is an experimental feature. |
a5222a85 |
539 | |
d4629d6a |
540 | In previous versions of Perl, you couldn't cache objects so as |
541 | to allow them to be deleted if the last reference from outside |
542 | the cache is deleted. The reference in the cache would hold a |
543 | reference count on the object and the objects would never be |
544 | destroyed. |
545 | |
546 | Another familiar problem is with circular references. When an |
547 | object references itself, its reference count would never go |
548 | down to zero, and it would not get destroyed until the program |
549 | is about to exit. |
550 | |
551 | Weak references solve this by allowing you to "weaken" any |
552 | reference, that is, make it not count towards the reference count. |
553 | When the last non-weak reference to an object is deleted, the object |
554 | is destroyed and all the weak references to the object are |
555 | automatically undef-ed. |
a5222a85 |
556 | |
d4629d6a |
557 | To use this feature, you need the WeakRef package from CPAN, which |
558 | contains additional documentation. |
559 | |
becf2bd3 |
560 | =head2 File globbing implemented internally |
561 | |
642f9deb |
562 | WARNING: This is currently an experimental feature. Interfaces and |
563 | implementation are likely to change. |
becf2bd3 |
564 | |
52bb0670 |
565 | Perl now uses the File::Glob implementation of the glob() operator |
566 | automatically. This avoids using an external csh process and the |
567 | problems associated with it. |
becf2bd3 |
568 | |
5fdc711f |
569 | =head2 Binary numbers supported |
570 | |
4f19785b |
571 | Binary numbers are now supported as literals, in s?printf formats, and |
572 | C<oct()>: |
573 | |
14218588 |
574 | $answer = 0b101010; |
575 | printf "The answer is: %b\n", oct("0b101010"); |
4f19785b |
576 | |
a5222a85 |
577 | =head2 Some arrows may be omitted in calls through references |
578 | |
579 | Perl now allows the arrow to be omitted in many constructs |
580 | involving subroutine calls through references. For example, |
c47ff5f1 |
581 | C<< $foo[10]->('foo') >> may now be written C<$foo[10]('foo')>. |
a5222a85 |
582 | This is rather similar to how the arrow may be omitted from |
c47ff5f1 |
583 | C<< $foo[10]->{'foo'} >>. Note however, that the arrow is still |
584 | required for C<< foo(10)->('bar') >>. |
a5222a85 |
585 | |
afebc493 |
586 | =head2 exists() is supported on subroutine names |
587 | |
588 | The exists() builtin now works on subroutine names. A subroutine |
589 | is considered to exist if it has been declared (even if implicitly). |
590 | See L<perlfunc/exists> for examples. |
591 | |
01020589 |
592 | =head2 exists() and delete() are supported on array elements |
593 | |
594 | The exists() and delete() builtins now work on simple arrays as well. |
595 | The behavior is similar to that on hash elements. |
596 | |
8ea97a1e |
597 | exists() can be used to check whether an array element has been |
8216c1fd |
598 | initialized. This avoids autovivifying array elements that don't exist. |
599 | If the array is tied, the EXISTS() method in the corresponding tied |
600 | package will be invoked. |
8ea97a1e |
601 | |
602 | delete() may be used to remove an element from the array and return |
603 | it. The array element at that position returns to its unintialized |
604 | state, so that testing for the same element with exists() will return |
605 | false. If the element happens to be the one at the end, the size of |
8216c1fd |
606 | the array also shrinks up to the highest element that tests true for |
607 | exists(), or 0 if none such is found. If the array is tied, the DELETE() |
608 | method in the corresponding tied package will be invoked. |
01020589 |
609 | |
610 | See L<perlfunc/exists> and L<perlfunc/delete> for examples. |
611 | |
5fdc711f |
612 | =head2 syswrite() ease-of-use |
613 | |
a5222a85 |
614 | The length argument of C<syswrite()> has become optional. |
615 | |
b1a9ed4a |
616 | =head2 File and directory handles can be autovivified |
a5222a85 |
617 | |
c47ff5f1 |
618 | Similar to how constructs such as C<< $x->[0] >> autovivify a reference, |
b1a9ed4a |
619 | handle constructors (open(), opendir(), pipe(), socketpair(), sysopen(), |
620 | socket(), and accept()) now autovivify a file or directory handle |
621 | if the handle passed to them is an uninitialized scalar variable. This |
622 | allows the constructs such as C<open(my $fh, ...)> and C<open(local $fh,...)> |
623 | to be used to create filehandles that will conveniently be closed |
624 | automatically when the scope ends, provided there are no other references |
625 | to them. This largely eliminates the need for typeglobs when opening |
626 | filehandles that must be passed around, as in the following example: |
a5222a85 |
627 | |
628 | sub myopen { |
629 | open my $fh, "@_" |
630 | or die "Can't open '@_': $!"; |
631 | return $fh; |
632 | } |
633 | |
634 | { |
635 | my $f = myopen("</etc/motd"); |
636 | print <$f>; |
637 | # $f implicitly closed here |
638 | } |
639 | |
642f9deb |
640 | =head2 open() with more than two arguments |
641 | |
642 | If open() is passed three arguments instead of two, the second arguments |
643 | is used as the mode and the third argument is taken to be the file name. |
644 | This is primarily useful for protecting against unintended magic behavior |
645 | of the traditional two-argument form. See L<perlfunc/open>. |
6c67e1bb |
646 | |
5fdc711f |
647 | =head2 64-bit support |
648 | |
642f9deb |
649 | NOTE: The Configure flags -Duselonglong and -Duse64bits have been |
650 | deprecated. Use -Duse64bitint instead. |
10cc9d2a |
651 | |
652 | Any platform that has 64-bit integers either (a) natively as longs or |
642f9deb |
653 | ints (b) via special compiler flags, or (c) using long long are able to |
654 | use "quads" (64-bit integers) as follows: |
9c107f78 |
655 | |
656 | =over 4 |
657 | |
a5222a85 |
658 | =item * |
659 | |
660 | constants (decimal, hexadecimal, octal, binary) in the code |
661 | |
662 | =item * |
9c107f78 |
663 | |
a5222a85 |
664 | arguments to oct() and hex() |
9c107f78 |
665 | |
a5222a85 |
666 | =item * |
667 | |
668 | arguments to print(), printf() and sprintf() (flag prefixes ll, L, q) |
669 | |
670 | =item * |
9c107f78 |
671 | |
a5222a85 |
672 | printed as such |
9c107f78 |
673 | |
a5222a85 |
674 | =item * |
675 | |
676 | pack() and unpack() "q" and "Q" formats |
677 | |
678 | =item * |
679 | |
972b05a9 |
680 | in basic arithmetics: + - * / % (NOTE: operating close to the limits |
681 | of the integer values may produce surprising results) |
a5222a85 |
682 | |
683 | =item * |
1fad5d67 |
684 | |
972b05a9 |
685 | in bit arithmetics: & | ^ ~ << >> (NOTE: these used to be forced |
642f9deb |
686 | to be 32 bits wide but now operate on the full native width.) |
972b05a9 |
687 | |
688 | =item * |
689 | |
690 | vec() |
9c107f78 |
691 | |
692 | =back |
693 | |
694 | Note that unless you have the case (a) you will have to configure |
10cc9d2a |
695 | and compile Perl using the -Duse64bitint Configure flag. |
9c107f78 |
696 | |
49c10eea |
697 | There are actually two modes of 64-bitness: the first one is achieved |
10cc9d2a |
698 | using Configure -Duse64bitint and the second one using Configure |
699 | -Duse64bitall. The difference is that the first one is minimal and |
49c10eea |
700 | the second one maximal. The first one does only as much as is |
701 | required to get 64-bit integers into Perl (this may mean, for example, |
702 | using "long longs") while your memory may still be limited to 2 |
642f9deb |
703 | gigabytes (because your pointers are still allowed to be 32-bit); the |
704 | second one goes all the way by attempting to switch also longs (and |
705 | pointers) to being 64-bit. This may create an even more binary |
706 | incompatible Perl than -Duse64bitint: the resulting executable may not |
707 | run at all in a 32-bit box, or you may have to reboot/reconfigure/rebuild |
708 | your operating system to be 64-bit aware. |
49c10eea |
709 | |
10cc9d2a |
710 | Natively 64-bit systems like Alpha and Cray need neither -Duse64bitint |
711 | nor -Duse64bitall. |
49c10eea |
712 | |
2d4389e4 |
713 | Last but not least: note that due to Perl's habit of always using |
d0ba1bd2 |
714 | floating point numbers the quads are still not true integers. |
715 | When quads overflow their limits (0...18_446_744_073_709_551_615 unsigned, |
716 | -9_223_372_036_854_775_808...9_223_372_036_854_775_807 signed), they |
717 | are silently promoted to floating point numbers, after which they will |
642f9deb |
718 | start losing precision (in their lower digits). |
2d4389e4 |
719 | |
720 | =head2 Large file support |
721 | |
722 | If you have filesystems that support "large files" (files larger than |
aa855319 |
723 | 2 gigabytes), you may now also be able to create and access them from |
249b38c6 |
724 | Perl. You have to use Configure -Duselargefiles. Turning on the |
642f9deb |
725 | large file support also turns on 64-bit support on many platforms. |
822ba51d |
726 | Beware that unless your filesystem also supports "sparse files" seeking |
727 | to umpteen petabytes may be unadvisable. |
2d4389e4 |
728 | |
eed7fde4 |
729 | Note that in addition to requiring a proper file system to do large |
730 | files you may also need to adjust your per-process (or your |
731 | per-system, or per-process-group, or per-user-group) maximum filesize |
732 | limits before running Perl scripts that try to handle large files, |
733 | especially if you intend to write such files. |
734 | |
735 | Finally, in addition to your process/process group maximum filesize |
736 | limits, you may have quota limits on your filesystems that stop you |
737 | (your user id or your user group id) from using large files. |
738 | |
739 | Adjusting your process/user/group/file system/operating system limits |
740 | is outside the scope of Perl core language. For process limits, you |
741 | may try increasing the limits using your shell's limits/limit/ulimit |
742 | command before running Perl. The BSD::Resource extension (not |
743 | included with the standard Perl distribution) may also be of use, it |
744 | offers the getrlimit/setrlimit interface that can be used to adjust |
745 | process resource usage limits, including the maximum filesize limit. |
475d79b5 |
746 | |
aa855319 |
747 | =head2 Long doubles |
748 | |
749 | In some systems you may be able to use long doubles to enhance the |
822ba51d |
750 | range and precision of your double precision floating point numbers |
aa855319 |
751 | (that is, Perl's numbers). Use Configure -Duselongdouble to enable |
752 | this support (if it is available). |
753 | |
754 | =head2 "more bits" |
755 | |
822ba51d |
756 | You can "Configure -Dusemorebits" to turn on both the 64-bit support |
aa855319 |
757 | and the long double support. |
09bef843 |
758 | |
43481408 |
759 | =head2 Enhanced support for sort() subroutines |
760 | |
642f9deb |
761 | Perl subroutines with a prototype of C<($$)>, and XSUBs in general, can |
43481408 |
762 | now be used as sort subroutines. In either case, the two elements to |
af365420 |
763 | be compared are passed as normal parameters in @_. See L<perlfunc/sort>. |
43481408 |
764 | |
765 | For unprototyped sort subroutines, the historical behavior of passing |
766 | the elements to be compared as the global variables $a and $b remains |
767 | unchanged. |
768 | |
62c18ce2 |
769 | =head2 Better syntax checks on parenthesized unary operators |
770 | |
771 | Expressions such as: |
772 | |
14218588 |
773 | print defined(&foo,&bar,&baz); |
774 | print uc("foo","bar","baz"); |
775 | undef($foo,&bar); |
62c18ce2 |
776 | |
7711098a |
777 | used to be accidentally allowed in earlier versions, and produced |
14218588 |
778 | unpredictable behaviour. Some produced ancillary warnings |
779 | when used in this way; others silently did the wrong thing. |
62c18ce2 |
780 | |
781 | The parenthesized forms of most unary operators that expect a single |
14218588 |
782 | argument now ensure that they are not called with more than one |
783 | argument, making the cases shown above syntax errors. The usual |
784 | behaviour of: |
62c18ce2 |
785 | |
14218588 |
786 | print defined &foo, &bar, &baz; |
787 | print uc "foo", "bar", "baz"; |
788 | undef $foo, &bar; |
62c18ce2 |
789 | |
790 | remains unchanged. See L<perlop>. |
791 | |
3e3318e7 |
792 | =head2 POSIX character class syntax [: :] supported |
793 | |
794 | For example to match alphabetic characters use /[[:alpha:]]/. |
795 | See L<perlre> for details. |
796 | |
5a929a98 |
797 | =head2 Improved C<qw//> operator |
8127e0e3 |
798 | |
26ef7447 |
799 | The C<qw//> operator is now evaluated at compile time into a true list |
800 | instead of being replaced with a run time call to C<split()>. This |
14218588 |
801 | removes the confusing misbehaviour of C<qw//> in scalar context, which |
802 | had inherited that behaviour from split(). |
26ef7447 |
803 | |
804 | Thus: |
805 | |
806 | $foo = ($bar) = qw(a b c); print "$foo|$bar\n"; |
807 | |
808 | now correctly prints "3|a", instead of "2|a". |
8127e0e3 |
809 | |
5a929a98 |
810 | =head2 pack() format 'Z' supported |
811 | |
812 | The new format type 'Z' is useful for packing and unpacking null-terminated |
813 | strings. See L<perlfunc/"pack">. |
814 | |
4d0c1c44 |
815 | =head2 pack() format modifier '!' supported |
ee3907e2 |
816 | |
14218588 |
817 | The new format type modifier '!' is useful for packing and unpacking |
ee3907e2 |
818 | native shorts, ints, and longs. See L<perlfunc/"pack">. |
819 | |
f29c64d6 |
820 | =head2 pack() and unpack() support counted strings |
821 | |
a5222a85 |
822 | The template character '/' can be used to specify a counted string |
f29c64d6 |
823 | type to be packed or unpacked. See L<perlfunc/"pack">. |
824 | |
a5222a85 |
825 | =head2 Comments in pack() templates |
826 | |
827 | The '#' character in a template introduces a comment up to |
828 | end of the line. This facilitates documentation of pack() |
829 | templates. |
830 | |
2b92dfce |
831 | =head2 $^X variables may now have names longer than one character |
832 | |
833 | Formerly, $^X was synonymous with ${"\cX"}, but $^XY was a syntax |
834 | error. Now variable names that begin with a control character may be |
835 | arbitrarily long. However, for compatibility reasons, these variables |
836 | I<must> be written with explicit braces, as C<${^XY}> for example. |
14218588 |
837 | C<${^XYZ}> is synonymous with ${"\cXYZ"}. Variable names with more |
2b92dfce |
838 | than one control character, such as C<${^XY^Z}>, are illegal. |
839 | |
14218588 |
840 | The old syntax has not changed. As before, `^X' may be either a |
841 | literal control-X character or the two-character sequence `caret' plus |
842 | `X'. When braces are omitted, the variable name stops after the |
2b92dfce |
843 | control character. Thus C<"$^XYZ"> continues to be synonymous with |
7711098a |
844 | C<$^X . "YZ"> as before. |
2b92dfce |
845 | |
846 | As before, lexical variables may not have names beginning with control |
847 | characters. As before, variables whose names begin with a control |
14218588 |
848 | character are always forced to be in package `main'. All such variables |
849 | are reserved for future extensions, except those that begin with |
09bef843 |
850 | C<^_>, which may be used by user programs and are guaranteed not to |
14218588 |
851 | acquire special meaning in any future version of Perl. |
2b92dfce |
852 | |
09bef843 |
853 | =head2 C<use attrs> implicit in subroutine attributes |
854 | |
855 | Formerly, if you wanted to mark a subroutine as being a method call or |
856 | as requiring an automatic lock() when it is entered, you had to declare |
857 | that with a C<use attrs> pragma in the body of the subroutine. |
16070b82 |
858 | That can now be accomplished with declaration syntax, like this: |
09bef843 |
859 | |
0120eecf |
860 | sub mymethod : locked method ; |
09bef843 |
861 | ... |
16070b82 |
862 | sub mymethod : locked method { |
863 | ... |
864 | } |
865 | |
866 | sub othermethod :locked :method ; |
867 | ... |
868 | sub othermethod :locked :method { |
09bef843 |
869 | ... |
870 | } |
871 | |
16070b82 |
872 | |
873 | (Note how only the first C<:> is mandatory, and whitespace surrounding |
874 | the C<:> is optional.) |
875 | |
09bef843 |
876 | F<AutoSplit.pm> and F<SelfLoader.pm> have been updated to keep the attributes |
877 | with the stubs they provide. See L<attributes>. |
878 | |
a5222a85 |
879 | =head2 Support for interpolating named characters |
880 | |
21bad921 |
881 | The new C<\N> escape interpolates named characters within strings. |
882 | For example, C<"Hi! \N{WHITE SMILING FACE}"> evaluates to a string |
883 | with a unicode smiley face at the end. |
a5222a85 |
884 | |
a5222a85 |
885 | =head2 C<require> and C<do> may be overridden |
886 | |
887 | C<require> and C<do 'file'> operations may be overridden locally |
888 | by importing subroutines of the same name into the current package |
889 | (or globally by importing them into the CORE::GLOBAL:: namespace). |
890 | Overriding C<require> will also affect C<use>, provided the override |
891 | is visible at compile-time. |
892 | See L<perlsub/"Overriding Built-in Functions">. |
893 | |
894 | =head2 New variable $^C reflects C<-c> switch |
895 | |
08cd8952 |
896 | C<$^C> has a boolean value that reflects whether perl is being run |
a5222a85 |
897 | in compile-only mode (i.e. via the C<-c> switch). Since |
898 | BEGIN blocks are executed under such conditions, this variable |
899 | enables perl code to determine whether actions that make sense |
900 | only during normal running are warranted. See L<perlvar>. |
901 | |
063663a9 |
902 | =head2 New variable $^V contains Perl version as a string |
16070b82 |
903 | |
da2094fd |
904 | C<$^V> contains the Perl version number as a string composed of |
642f9deb |
905 | characters whose ordinals match the version numbers, i.e. v5.6.0. |
063663a9 |
906 | This may be used in string comparisons. |
44dcb63b |
907 | |
908 | See C<Support for strings represented as a vector of ordinals> for an |
909 | example. |
16070b82 |
910 | |
a5222a85 |
911 | =head2 Optional Y2K warnings |
912 | |
913 | If Perl is built with the cpp macro C<PERL_Y2KWARN> defined, |
914 | it emits optional warnings when concatenating the number 19 |
915 | with another number. |
916 | |
917 | This behavior must be specifically enabled when running Configure. |
b4bc034f |
918 | See F<INSTALL> and F<README.Y2K>. |
a5222a85 |
919 | |
fbad3eb5 |
920 | =head1 Significant bug fixes |
921 | |
c47ff5f1 |
922 | =head2 <HANDLE> on empty files |
fbad3eb5 |
923 | |
191f2cf3 |
924 | With C<$/> set to C<undef>, "slurping" an empty file returns a string of |
14218588 |
925 | zero length (instead of C<undef>, as it used to) the first time the |
191f2cf3 |
926 | HANDLE is read after C<$/> is set to C<undef>. Further reads yield |
927 | C<undef>. |
fbad3eb5 |
928 | |
929 | This means that the following will append "foo" to an empty file (it used |
14218588 |
930 | to do nothing): |
fbad3eb5 |
931 | |
932 | perl -0777 -pi -e 's/^/foo/' empty_file |
933 | |
14218588 |
934 | The behaviour of: |
fbad3eb5 |
935 | |
936 | perl -pi -e 's/^/foo/' empty_file |
937 | |
938 | is unchanged (it continues to leave the file empty). |
939 | |
0244c3a4 |
940 | =head2 C<eval '...'> improvements |
941 | |
942 | Line numbers (as reflected by caller() and most diagnostics) within |
642f9deb |
943 | C<eval '...'> were often incorrect where here documents were involved. |
0244c3a4 |
944 | This has been corrected. |
945 | |
946 | Lexical lookups for variables appearing in C<eval '...'> within |
947 | functions that were themselves called within an C<eval '...'> were |
14218588 |
948 | searching the wrong place for lexicals. The lexical search now |
949 | correctly ends at the subroutine's block boundary. |
0244c3a4 |
950 | |
951 | Parsing of here documents used to be flawed when they appeared as |
952 | the replacement expression in C<eval 's/.../.../e'>. This has |
953 | been fixed. |
954 | |
a5222a85 |
955 | =head2 All compilation errors are true errors |
956 | |
957 | Some "errors" encountered at compile time were by neccessity |
958 | generated as warnings followed by eventual termination of the |
959 | program. This enabled more such errors to be reported in a |
960 | single run, rather than causing a hard stop at the first error |
961 | that was encountered. |
962 | |
963 | The mechanism for reporting such errors has been reimplemented |
964 | to queue compile-time errors and report them at the end of the |
965 | compilation as true errors rather than as warnings. This fixes |
08cd8952 |
966 | cases where error messages leaked through in the form of warnings |
967 | when code was compiled at run time using C<eval STRING>, and |
642f9deb |
968 | also allows such errors to be reliably trapped using C<eval "...">. |
a5222a85 |
969 | |
45bc9206 |
970 | =head2 Automatic flushing of output buffers |
971 | |
14218588 |
972 | fork(), exec(), system(), qx//, and pipe open()s now flush buffers |
642f9deb |
973 | of all files opened for output when the operation was attempted. This |
974 | mostly eliminates confusing buffering mishaps suffered by users unaware |
975 | of how Perl internally handles I/O. |
45bc9206 |
976 | |
023ceb80 |
977 | This is not supported on some platforms like Solaris where a suitably |
978 | correct implementation of fflush(NULL) isn't available. |
979 | |
af8c498a |
980 | =head2 Better diagnostics on meaningless filehandle operations |
981 | |
c47ff5f1 |
982 | Constructs such as C<< open(<FH>) >> and C<< close(<FH>) >> |
af8c498a |
983 | are compile time errors. Attempting to read from filehandles that |
984 | were opened only for writing will now produce warnings (just as |
985 | writing to read-only filehandles does). |
986 | |
a5222a85 |
987 | =head2 Where possible, buffered data discarded from duped input filehandle |
988 | |
c47ff5f1 |
989 | C<< open(NEW, "<&OLD") >> now attempts to discard any data that |
a5222a85 |
990 | was previously read and buffered in C<OLD> before duping the handle. |
991 | On platforms where doing this is allowed, the next read operation |
992 | on C<NEW> will return the same data as the corresponding operation |
993 | on C<OLD>. Formerly, it would have returned the data from the start |
994 | of the following disk block instead. |
995 | |
820475bd |
996 | =head2 eof() has the same old magic as <> |
997 | |
c47ff5f1 |
998 | C<eof()> would return true if no attempt to read from C<< <> >> had |
820475bd |
999 | yet been made. C<eof()> has been changed to have a little magic of its |
c47ff5f1 |
1000 | own, it now opens the C<< <> >> files. |
820475bd |
1001 | |
a5222a85 |
1002 | =head2 system(), backticks and pipe open now reflect exec() failure |
1003 | |
1004 | On Unix and similar platforms, system(), qx() and open(FOO, "cmd |") |
1005 | etc., are implemented via fork() and exec(). When the underlying |
1006 | exec() fails, earlier versions did not report the error properly, |
1007 | since the exec() happened to be in a different process. |
1008 | |
1009 | The child process now communicates with the parent about the |
437784d6 |
1010 | error in launching the external command, which allows these |
a5222a85 |
1011 | constructs to return with their usual error value and set $!. |
1012 | |
1013 | =head2 Implicitly closed filehandles are safer |
1014 | |
1015 | Sometimes implicitly closed filehandles (as when they are localized, |
1016 | and Perl automatically closes them on exiting the scope) could |
1017 | inadvertently set $? or $!. This has been corrected. |
1018 | |
1019 | =head2 C<(\$)> prototype and C<$foo{a}> |
1020 | |
642f9deb |
1021 | A scalar reference prototype now correctly allows a hash or |
a5222a85 |
1022 | array element in that slot. |
1023 | |
1024 | =head2 Pseudo-hashes work better |
1025 | |
1026 | Dereferencing some types of reference values in a pseudo-hash, |
c47ff5f1 |
1027 | such as C<< $ph->{foo}[1] >>, was accidentally disallowed. This has |
a5222a85 |
1028 | been corrected. |
1029 | |
1030 | When applied to a pseudo-hash element, exists() now reports whether |
1031 | the specified value exists, not merely if the key is valid. |
1032 | |
01020589 |
1033 | delete() now works on pseudo-hashes. When given a pseudo-hash element |
1034 | or slice it deletes the values corresponding to the keys (but not the keys |
1035 | themselves). See L<perlref/"Pseudo-hashes: Using an array as a hash">. |
1036 | |
479ba383 |
1037 | Pseudo-hash slices with constant keys are now optimized to array lookups |
1038 | at compile-time. |
1039 | |
1040 | The C<fields> pragma now provides ways to create pseudo-hashes, via |
1041 | fields::new() and fields::phash(). See L<fields>. |
1042 | |
a5222a85 |
1043 | =head2 C<goto &sub> and AUTOLOAD |
1044 | |
08cd8952 |
1045 | The C<goto &sub> construct works correctly when C<&sub> happens |
a5222a85 |
1046 | to be autoloaded. |
1047 | |
1048 | =head2 C<-bareword> allowed under C<use integer> |
1049 | |
1050 | The autoquoting of barewords preceded by C<-> did not work |
1051 | in prior versions when the C<integer> pragma was enabled. |
1052 | This has been fixed. |
1053 | |
1054 | =head2 Boolean assignment operators are legal lvalues |
1055 | |
1056 | Constructs such as C<($a ||= 2) += 1> are now allowed. |
1057 | |
1058 | =head2 C<sort $coderef @foo> allowed |
1059 | |
1060 | sort() did not accept a subroutine reference as the comparison |
08cd8952 |
1061 | function in earlier versions. This is now permitted. |
a5222a85 |
1062 | |
1063 | =head2 Failures in DESTROY() |
1064 | |
1065 | When code in a destructor threw an exception, it went unnoticed |
1066 | in earlier versions of Perl, unless someone happened to be |
1067 | looking in $@ just after the point the destructor happened to |
1068 | run. Such failures are now visible as warnings when warnings are |
1069 | enabled. |
1070 | |
1071 | =head2 Locale bugs fixed |
54195c32 |
1072 | |
437784d6 |
1073 | printf() and sprintf() previously reset the numeric locale |
67d3893f |
1074 | back to the default "C" locale. This has been fixed. |
1075 | |
1076 | Numbers formatted according to the local numeric locale |
1077 | (such as using a decimal comma instead of a decimal dot) caused |
1078 | "isn't numeric" warnings, even while the operations accessing |
642f9deb |
1079 | those numbers produced correct results. These warnings have been |
1080 | discontinued. |
54195c32 |
1081 | |
a5222a85 |
1082 | =head2 Memory leaks |
1083 | |
1084 | The C<eval 'return sub {...}'> construct could sometimes leak |
1085 | memory. This has been fixed. |
1086 | |
1087 | Operations that aren't filehandle constructors used to leak memory |
1088 | when used on invalid filehandles. This has been fixed. |
1089 | |
1090 | Constructs that modified C<@_> could fail to deallocate values |
1091 | in C<@_> and thus leak memory. This has been corrected. |
1092 | |
1093 | =head2 Spurious subroutine stubs after failed subroutine calls |
1094 | |
1095 | Perl could sometimes create empty subroutine stubs when a |
1096 | subroutine was not found in the package. Such cases stopped |
1097 | later method lookups from progressing into base packages. |
1098 | This has been corrected. |
1099 | |
a5222a85 |
1100 | =head2 Taint failures under C<-U> |
1101 | |
1102 | When running in unsafe mode, taint violations could sometimes |
1103 | cause silent failures. This has been fixed. |
1104 | |
1105 | =head2 END blocks and the C<-c> switch |
1106 | |
1107 | Prior versions used to run BEGIN B<and> END blocks when Perl was |
1108 | run in compile-only mode. Since this is typically not the expected |
08cd8952 |
1109 | behavior, END blocks are not executed anymore when the C<-c> switch |
a5222a85 |
1110 | is used. |
1111 | |
7d30b5c4 |
1112 | See L<CHECK blocks> for how to run things when the compile phase ends. |
a5222a85 |
1113 | |
1114 | =head2 Potential to leak DATA filehandles |
1115 | |
1116 | Using the C<__DATA__> token creates an implicit filehandle to |
1117 | the file that contains the token. It is the program's |
1118 | responsibility to close it when it is done reading from it. |
1119 | |
1120 | This caveat is now better explained in the documentation. |
1121 | See L<perldata>. |
1122 | |
1123 | =head2 Diagnostics follow STDERR |
1124 | |
1125 | Diagnostic output now goes to whichever file the C<STDERR> handle |
1126 | is pointing at, instead of always going to the underlying C runtime |
1127 | library's C<stderr>. |
1128 | |
1129 | =head2 Other fixes for better diagnostics |
1130 | |
437784d6 |
1131 | Line numbers are no longer suppressed (under most likely circumstances) |
a5222a85 |
1132 | during the global destruction phase. |
1133 | |
1134 | Diagnostics emitted from code running in threads other than the main |
1135 | thread are now accompanied by the thread ID. |
1136 | |
1137 | Embedded null characters in diagnostics now actually show up. They |
1138 | used to truncate the message in prior versions. |
1139 | |
1140 | $foo::a and $foo::b are now exempt from "possible typo" warnings only |
642f9deb |
1141 | if sort() is encountered in package C<foo>. |
a5222a85 |
1142 | |
501fbaef |
1143 | Unrecognized alphabetic escapes encountered when parsing quote |
a5222a85 |
1144 | constructs now generate a warning, since they may take on new |
1145 | semantics in later versions of Perl. |
1146 | |
1147 | =head1 Performance enhancements |
1148 | |
1149 | =head2 Simple sort() using { $a <=> $b } and the like are optimized |
1150 | |
08cd8952 |
1151 | Many common sort() operations using a simple inlined block are now |
a5222a85 |
1152 | optimized for faster performance. |
1153 | |
1154 | =head2 Optimized assignments to lexical variables |
1155 | |
1156 | Certain operations in the RHS of assignment statements have been |
1157 | optimized to directly set the lexical variable on the LHS, |
1158 | eliminating redundant copying overheads. |
1159 | |
a5222a85 |
1160 | =head2 Faster subroutine calls |
1161 | |
1162 | Minor changes in how subroutine calls are handled internally |
1163 | provide marginal improvements in performance. |
1164 | |
1165 | =head1 Platform specific changes |
1166 | |
063663a9 |
1167 | =head2 Supported platforms |
ba8251e8 |
1168 | |
5fdc711f |
1169 | =over 4 |
1170 | |
1171 | =item * |
1172 | |
6c67e1bb |
1173 | VM/ESA is now supported. |
1174 | |
5fdc711f |
1175 | =item * |
1176 | |
ee3907e2 |
1177 | Siemens BS2000 is now supported under the POSIX Shell. |
1178 | |
1179 | =item * |
1180 | |
2bb14304 |
1181 | The Mach CThreads (NEXTSTEP, OPENSTEP) are now supported by the Thread |
1182 | extension. |
6c67e1bb |
1183 | |
5fdc711f |
1184 | =item * |
1185 | |
ee3907e2 |
1186 | GNU/Hurd is now supported. |
6c67e1bb |
1187 | |
00ad96e1 |
1188 | =item * |
1189 | |
063663a9 |
1190 | Rhapsody/Darwin is now supported. |
00ad96e1 |
1191 | |
27806c82 |
1192 | =item * |
1193 | |
1194 | EPOC is is now supported (on Psion 5). |
1195 | |
5fdc711f |
1196 | =back |
1197 | |
a5222a85 |
1198 | =head2 DOS |
1199 | |
d524f05e |
1200 | =over 4 |
1201 | |
1202 | =item * |
1203 | |
1204 | Perl now works with djgpp 2.02 (and 2.03 alpha). |
1205 | |
1206 | =item * |
1207 | |
1208 | Environment variable names are not converted to uppercase any more. |
1209 | |
1210 | =item * |
1211 | |
642f9deb |
1212 | Incorrect exit codes from backticks have been fixed. |
d524f05e |
1213 | |
1214 | =item * |
1215 | |
642f9deb |
1216 | This port continues to use its own builtin globbing (not File::Glob). |
d524f05e |
1217 | |
1218 | =back |
a5222a85 |
1219 | |
c6018dae |
1220 | =head2 OS390 (OpenEdition MVS) |
063663a9 |
1221 | |
1222 | Support for this EBCDIC platform has not been renewed in this release. |
1223 | There are difficulties in reconciling Perl's standardization on UTF-8 |
1224 | as its internal representation for characters with the EBCDIC character |
1225 | set, because the two are incompatible. |
1226 | |
1227 | It is unclear whether future versions will renew support for this |
1228 | platform, but the possibility exists. |
1229 | |
a5222a85 |
1230 | =head2 VMS |
1231 | |
c93fa817 |
1232 | Numerous revisions and extensions to configuration, build, testing, and |
642f9deb |
1233 | installation process to accomodate core changes and VMS-specific options. |
c93fa817 |
1234 | |
1235 | Expand %ENV-handling code to allow runtime mapping to logical names, |
642f9deb |
1236 | CLI symbols, and CRTL environ array. |
c93fa817 |
1237 | |
642f9deb |
1238 | Extension of subprocess invocation code to accept filespecs as command |
1239 | "verbs". |
c93fa817 |
1240 | |
1241 | Add to Perl command line processing the ability to use default file types and |
642f9deb |
1242 | to recognize Unix-style C<2E<gt>&1>. |
c93fa817 |
1243 | |
642f9deb |
1244 | Expansion of File::Spec::VMS routines, and integration into ExtUtils::MM_VMS. |
c93fa817 |
1245 | |
642f9deb |
1246 | Extension of ExtUtils::MM_VMS to handle complex extensions more flexibly. |
c93fa817 |
1247 | |
1248 | Barewords at start of Unix-syntax paths may be treated as text rather than |
642f9deb |
1249 | only as logical names. |
c93fa817 |
1250 | |
642f9deb |
1251 | Optional secure translation of several logical names used internally by Perl. |
c93fa817 |
1252 | |
642f9deb |
1253 | Miscellaneous bugfixing and porting of new core code to VMS. |
c93fa817 |
1254 | |
1255 | Thanks are gladly extended to the many people who have contributed VMS |
1256 | patches, testing, and ideas. |
a5222a85 |
1257 | |
1258 | =head2 Win32 |
1259 | |
642f9deb |
1260 | Perl can now emulate fork() internally, using multiple interpreters running |
1261 | in different concurrent threads. This support must be enabled at build |
1262 | time. See L<perlfork> for detailed information. |
a5222a85 |
1263 | |
642f9deb |
1264 | When given a pathname that consists only of a drivename, such as C<A:>, |
1265 | opendir() and stat() now use the current working directory for the drive |
1266 | rather than the drive root. |
a5222a85 |
1267 | |
642f9deb |
1268 | The builtin XSUB functions in the Win32:: namespace are documented. See |
1269 | L<Win32>. |
a5222a85 |
1270 | |
1271 | $^X now contains the full path name of the running executable. |
1272 | |
1273 | A Win32::GetLongPathName() function is provided to complement |
1274 | Win32::GetFullPathName() and Win32::GetShortPathName(). See L<Win32>. |
1275 | |
1276 | POSIX::uname() is supported. |
1277 | |
1278 | system(1,...) now returns true process IDs rather than process |
1279 | handles. kill() accepts any real process id, rather than strictly |
1280 | return values from system(1,...). |
1281 | |
42b8b86c |
1282 | For better compatibility with Unix, C<kill(0, $pid)> can now be used to |
1283 | test whether a process exists. |
1284 | |
a5222a85 |
1285 | The C<Shell> module is supported. |
1286 | |
642f9deb |
1287 | Better support for building Perl under command.com in Windows 95 |
883d36a6 |
1288 | has been added. |
1289 | |
c39cd008 |
1290 | Scripts are read in binary mode by default to allow ByteLoader (and |
1291 | the filter mechanism in general) to work properly. For compatibility, |
53129d29 |
1292 | the DATA filehandle will be set to text mode if a carriage return is |
1293 | detected at the end of the line containing the __END__ or __DATA__ |
1294 | token; if not, the DATA filehandle will be left open in binary mode. |
1295 | Earlier versions always opened the DATA filehandle in text mode. |
c39cd008 |
1296 | |
3a4b19e4 |
1297 | The glob() operator is implemented via the C<File::Glob> extension, |
8004f2ac |
1298 | which supports glob syntax of the C shell. This increases the flexibility |
16070b82 |
1299 | of the glob() operator, but there may be compatibility issues for |
1300 | programs that relied on the older globbing syntax. If you want to |
642f9deb |
1301 | preserve compatibility with the older syntax, you might want to run |
1302 | perl with C<-MFile::DosGlob>. For details and compatibility information, |
1303 | see L<File::Glob>. |
16070b82 |
1304 | |
6c67e1bb |
1305 | =head1 New tests |
1306 | |
1307 | =over 4 |
1308 | |
09bef843 |
1309 | =item lib/attrs |
1310 | |
1311 | Compatibility tests for C<sub : attrs> vs the older C<use attrs>. |
1312 | |
2675e62c |
1313 | =item lib/env |
1314 | |
1315 | Tests for new environment scalar capability (e.g., C<use Env qw($BAR);>). |
1316 | |
1317 | =item lib/env-array |
1318 | |
1319 | Tests for new environment array capability (e.g., C<use Env qw(@PATH);>). |
1320 | |
09bef843 |
1321 | =item lib/io_const |
6c67e1bb |
1322 | |
1323 | IO constants (SEEK_*, _IO*). |
14218588 |
1324 | |
09bef843 |
1325 | =item lib/io_dir |
6c67e1bb |
1326 | |
1327 | Directory-related IO methods (new, read, close, rewind, tied delete). |
1328 | |
09bef843 |
1329 | =item lib/io_multihomed |
6c67e1bb |
1330 | |
1331 | INET sockets with multi-homed hosts. |
1332 | |
09bef843 |
1333 | =item lib/io_poll |
6c67e1bb |
1334 | |
1335 | IO poll(). |
1336 | |
09bef843 |
1337 | =item lib/io_unix |
6c67e1bb |
1338 | |
1339 | UNIX sockets. |
1340 | |
09bef843 |
1341 | =item op/attrs |
1342 | |
1343 | Regression tests for C<my ($x,@y,%z) : attrs> and <sub : attrs>. |
1344 | |
6c67e1bb |
1345 | =item op/filetest |
1346 | |
1347 | File test operators. |
1348 | |
1349 | =item op/lex_assign |
1350 | |
5fdc711f |
1351 | Verify operations that access pad objects (lexicals and temporaries). |
6c67e1bb |
1352 | |
afebc493 |
1353 | =item op/exists_sub |
1354 | |
1355 | Verify C<exists &sub> operations. |
1356 | |
6c67e1bb |
1357 | =back |
e02fdbd2 |
1358 | |
ba8251e8 |
1359 | =head1 Modules and Pragmata |
1360 | |
3e8c4fa0 |
1361 | =head2 Modules |
1362 | |
b7d8191e |
1363 | =over 4 |
1364 | |
09bef843 |
1365 | =item attributes |
1366 | |
1367 | While used internally by Perl as a pragma, this module also |
1368 | provides a way to fetch subroutine and variable attributes. |
1369 | See L<attributes>. |
1370 | |
a5222a85 |
1371 | =item B |
1372 | |
642f9deb |
1373 | WARNING: The Compiler suite remains highly experimental. The |
1374 | generated code may not be correct, even it manages to execute |
1375 | without errors. |
501fbaef |
1376 | |
c6018dae |
1377 | The Perl Compiler suite has been extensively reworked for this |
1378 | release. More of the standard Perl testsuite passes when run |
1379 | under the Compiler, but there is still a significant way to |
1380 | go to achieve production quality compiled executables. |
a5222a85 |
1381 | |
f29c64d6 |
1382 | =item ByteLoader |
1383 | |
a5222a85 |
1384 | The ByteLoader is a dedicated extension to generate and run |
f29c64d6 |
1385 | Perl bytecode. See L<ByteLoader>. |
1386 | |
a5222a85 |
1387 | =item constant |
1388 | |
83763826 |
1389 | References can now be used. |
1390 | |
1391 | The new version also allows a leading underscore in constant names, but |
1392 | disallows a double leading underscore (as in "__LINE__"). Some other names |
1393 | are disallowed or warned against, including BEGIN, END, etc. Some names |
1394 | which were forced into main:: used to fail silently in some cases; now they're |
1395 | fatal (outside of main::) and an optional warning (inside of main::). |
1396 | The ability to detect whether a constant had been set with a given name has |
1397 | been added. |
1398 | |
1399 | See L<constant>. |
a5222a85 |
1400 | |
1401 | =item charnames |
1402 | |
21bad921 |
1403 | This pragma implements the C<\N> string escape. See L<charnames>. |
a5222a85 |
1404 | |
1405 | =item Data::Dumper |
1406 | |
1407 | A C<Maxdepth> setting can be specified to avoid venturing |
73b437c8 |
1408 | too deeply into deep data structures. See L<Data::Dumper>. |
a5222a85 |
1409 | |
0f1923bd |
1410 | The XSUB implementation of Dump() is now automatically called if the |
1411 | C<Useqq> setting is not in use. |
1412 | |
a5222a85 |
1413 | Dumping C<qr//> objects works correctly. |
1414 | |
1415 | =item DB |
1416 | |
1417 | C<DB> is an experimental module that exposes a clean abstraction |
1418 | to Perl's debugging API. |
1419 | |
1420 | =item DB_File |
1421 | |
0536e0eb |
1422 | DB_File can now be built with Berkeley DB versions 1, 2 or 3. |
1423 | See C<ext/DB_File/Changes>. |
a5222a85 |
1424 | |
f29c64d6 |
1425 | =item Devel::DProf |
1426 | |
9e107c59 |
1427 | Devel::DProf, a Perl source code profiler has been added. See |
1428 | L<Devel::DProf> and L<dprofpp>. |
f29c64d6 |
1429 | |
b7d8191e |
1430 | =item Dumpvalue |
1431 | |
437784d6 |
1432 | The Dumpvalue module provides screen dumps of Perl data. |
b7d8191e |
1433 | |
1434 | =item Benchmark |
1435 | |
54e82ce5 |
1436 | Overall, Benchmark results exhibit lower average error and better timing |
1437 | accuracy. |
1438 | |
868cb350 |
1439 | You can now run tests for I<n> seconds instead of guessing the right |
642f9deb |
1440 | number of tests to run: e.g., timethese(-5, ...) will run each |
14218588 |
1441 | code for at least 5 CPU seconds. Zero as the "number of repetitions" |
155776c0 |
1442 | means "for at least 3 CPU seconds". The output format has also |
14218588 |
1443 | changed. For example: |
155776c0 |
1444 | |
54e82ce5 |
1445 | use Benchmark;$x=3;timethese(-5,{a=>sub{$x*$x},b=>sub{$x**2}}) |
155776c0 |
1446 | |
1447 | will now output something like this: |
1448 | |
54e82ce5 |
1449 | Benchmark: running a, b, each for at least 5 CPU seconds... |
1450 | a: 5 wallclock secs ( 5.77 usr + 0.00 sys = 5.77 CPU) @ 200551.91/s (n=1156516) |
1451 | b: 4 wallclock secs ( 5.00 usr + 0.02 sys = 5.02 CPU) @ 159605.18/s (n=800686) |
155776c0 |
1452 | |
1453 | New features: "each for at least N CPU seconds...", "wallclock secs", |
1454 | and the "@ operations/CPU second (n=operations)". |
b7d8191e |
1455 | |
54e82ce5 |
1456 | timethese() now returns a reference to a hash of Benchmark objects containing |
1457 | the test results, keyed on the names of the tests. |
1458 | |
1459 | timethis() now returns the iterations field in the Benchmark result object |
1460 | instead of 0. |
1461 | |
1462 | timethese(), timethis(), and the new cmpthese() (see below) can also take |
1463 | a format specifier of 'none' to suppress output. |
1464 | |
1465 | A new function countit() is just like timeit() except that it takes a |
1466 | TIME instead of a COUNT. |
1467 | |
1468 | A new function cmpthese() prints a chart comparing the results of each test |
1469 | returned from a timethese() call. For each possible pair of tests, the |
1470 | percentage speed difference (iters/sec or seconds/iter) is shown. |
1471 | |
1472 | For other details, see L<Benchmark>. |
a5222a85 |
1473 | |
f505c983 |
1474 | =item Devel::Peek |
1475 | |
1476 | The Devel::Peek module provides access to the internal representation |
14218588 |
1477 | of Perl variables and data. It is a data debugging tool for the XS programmer. |
f505c983 |
1478 | |
44dcb63b |
1479 | =item English |
1480 | |
1481 | $PERL_VERSION now stands for C<$^V> (a string value) rather than for C<$]> |
1482 | (a numeric value). |
1483 | |
2675e62c |
1484 | =item Env |
1485 | |
1486 | Env now supports accessing environment variables like PATH as array |
1487 | variables. |
1488 | |
b7d8191e |
1489 | =item Fcntl |
1490 | |
1491 | More Fcntl constants added: F_SETLK64, F_SETLKW64, O_LARGEFILE for |
822ba51d |
1492 | large file (more than 4GB) access Note that the O_LARGEFILE is |
1493 | automatically/transparently added to sysopen() flags if large file |
1494 | support has been configured), Free/Net/OpenBSD locking behaviour flags |
1495 | F_FLOCK, F_POSIX, Linux F_SHLCK, and O_ACCMODE: the combined mask of |
ca6e1c26 |
1496 | O_RDONLY, O_WRONLY, and O_RDWR. The seek()/sysseek() constants |
1497 | SEEK_SET, SEEK_CUR, and SEEK_END are available via the C<:seek> tag. |
1498 | The chmod()/stat() S_IF* constants and S_IS* functions are available |
1499 | via the C<:mode> tag. |
1500 | |
b7d8191e |
1501 | |
a5222a85 |
1502 | =item File::Compare |
1503 | |
1504 | A compare_text() function has been added, which allows custom |
1505 | comparison functions. See L<File::Compare>. |
1506 | |
1507 | =item File::Find |
1508 | |
1509 | File::Find now works correctly when the wanted() function is either |
1510 | autoloaded or is a symbolic reference. |
1511 | |
08cd8952 |
1512 | A bug that caused File::Find to lose track of the working directory |
a5222a85 |
1513 | when pruning top-level directories has been fixed. |
1514 | |
81793b90 |
1515 | File::Find now also supports several other options to control its |
1516 | behavior. It can follow symbolic links if the C<follow> option is |
1517 | specified. Enabling the C<no_chdir> option will make File::Find skip |
1518 | changing the current directory when walking directories. The C<untaint> |
1519 | flag can be useful when running with taint checks enabled. |
1520 | |
1521 | See L<File::Find>. |
1522 | |
becf2bd3 |
1523 | =item File::Glob |
1524 | |
52bb0670 |
1525 | This extension implements BSD-style file globbing. By default, |
1526 | it will also be used for the internal implementation of the glob() |
1527 | operator. See L<File::Glob>. |
becf2bd3 |
1528 | |
f505c983 |
1529 | =item File::Spec |
1530 | |
1531 | New methods have been added to the File::Spec module: devnull() returns |
19799a22 |
1532 | the name of the null device (/dev/null on Unix) and tmpdir() the name of |
14218588 |
1533 | the temp directory (normally /tmp on Unix). There are now also methods |
f505c983 |
1534 | to convert between absolute and relative filenames: abs2rel() and |
14218588 |
1535 | rel2abs(). For compatibility with operating systems that specify volume |
1536 | names in file paths, the splitpath(), splitdir(), and catdir() methods |
f505c983 |
1537 | have been added. |
1538 | |
1539 | =item File::Spec::Functions |
1540 | |
1541 | The new File::Spec::Functions modules provides a function interface |
14218588 |
1542 | to the File::Spec module. Allows shorthand |
f505c983 |
1543 | |
14218588 |
1544 | $fullname = catfile($dir1, $dir2, $file); |
f505c983 |
1545 | |
1546 | instead of |
1547 | |
14218588 |
1548 | $fullname = File::Spec->catfile($dir1, $dir2, $file); |
f505c983 |
1549 | |
a5222a85 |
1550 | =item Getopt::Long |
1551 | |
c6edd1b7 |
1552 | Getopt::Long licensing has changed to allow the Perl Artistic License |
1553 | as well as the GPL. It used to be GPL only, which got in the way of |
1554 | non-GPL applications that wanted to use Getopt::Long. |
1555 | |
1556 | Getopt::Long encourages the use of Pod::Usage to produce help |
1557 | messages. For example: |
1558 | |
1559 | use Getopt::Long; |
1560 | use Pod::Usage; |
1561 | my $man = 0; |
1562 | my $help = 0; |
1563 | GetOptions('help|?' => \$help, man => \$man) or pod2usage(2); |
1564 | pod2usage(1) if $help; |
1565 | pod2usage(-exitstatus => 0, -verbose => 2) if $man; |
1566 | |
1567 | __END__ |
1568 | |
1569 | =head1 NAME |
1570 | |
1571 | sample - Using GetOpt::Long and Pod::Usage |
1572 | |
1573 | =head1 SYNOPSIS |
1574 | |
1575 | sample [options] [file ...] |
1576 | |
1577 | Options: |
1578 | -help brief help message |
1579 | -man full documentation |
1580 | |
1581 | =head1 OPTIONS |
1582 | |
1583 | =over 8 |
1584 | |
1585 | =item B<-help> |
1586 | |
1587 | Print a brief help message and exits. |
1588 | |
1589 | =item B<-man> |
1590 | |
1591 | Prints the manual page and exits. |
1592 | |
1593 | =back |
1594 | |
1595 | =head1 DESCRIPTION |
1596 | |
1597 | B<This program> will read the given input file(s) and do someting |
1598 | useful with the contents thereof. |
1599 | |
1600 | =cut |
1601 | |
1602 | See L<Pod::Usage> for details. |
1603 | |
c47ff5f1 |
1604 | A bug that prevented the non-option call-back <> from being |
c6edd1b7 |
1605 | specified as the first argument has been fixed. |
1606 | |
c47ff5f1 |
1607 | To specify the characters < and > as option starters, use ><. Note, |
1608 | however, that changing option starters is strongly deprecated. |
a5222a85 |
1609 | |
1610 | =item IO |
1611 | |
1612 | write() and syswrite() will now accept a single-argument |
1613 | form of the call, for consistency with Perl's syswrite(). |
1614 | |
1615 | You can now create a TCP-based IO::Socket::INET without forcing |
1616 | a connect attempt. This allows you to configure its options |
1617 | (like making it non-blocking) and then call connect() manually. |
1618 | |
1619 | A bug that prevented the IO::Socket::protocol() accessor |
1620 | from ever returning the correct value has been corrected. |
1621 | |
36f31b50 |
1622 | IO::Socket::connect now uses non-blocking IO instead of alarm() |
1623 | to do connect timeouts. |
1624 | |
1625 | IO::Socket::accept now uses select() instead of alarm() for doing |
1626 | timeouts. |
1627 | |
1628 | IO::Socket::INET->new now sets $! correctly on failure. $@ is |
1629 | still set for backwards compatability. |
1630 | |
a5222a85 |
1631 | =item JPL |
1632 | |
1633 | Java Perl Lingo is now distributed with Perl. See jpl/README |
1634 | for more information. |
1635 | |
883d36a6 |
1636 | =item lib |
1637 | |
1638 | C<use lib> now weeds out any trailing duplicate entries. |
1639 | C<no lib> removes all named entries. |
1640 | |
e16b8f49 |
1641 | =item Math::BigInt |
1642 | |
c47ff5f1 |
1643 | The bitwise operations C<<< << >>>, C<<< >> >>>, C<&>, C<|>, |
e16b8f49 |
1644 | and C<~> are now supported on bigints. |
1645 | |
b7d8191e |
1646 | =item Math::Complex |
7711098a |
1647 | |
14218588 |
1648 | The accessor methods Re, Im, arg, abs, rho, and theta can now also |
868cb350 |
1649 | act as mutators (accessor $z->Re(), mutator $z->Re(3)). |
b7d8191e |
1650 | |
16357284 |
1651 | The class method C<display_format> and the corresponding object method |
1652 | C<display_format>, in addition to accepting just one argument, now can |
1653 | also accept a parameter hash. Recognized keys of a parameter hash are |
1654 | C<"style">, which corresponds to the old one parameter case, and two |
1655 | new parameters: C<"format">, which is a printf()-style format string |
1656 | (defaults usually to C<"%.15g">, you can revert to the default by |
1657 | setting the format string to C<undef>) used for both parts of a |
1658 | complex number, and C<"polar_pretty_print"> (defaults to true), |
1659 | which controls whether an attempt is made to try to recognize small |
1660 | multiples and rationals of pi (2pi, pi/2) at the argument (angle) of a |
1661 | polar complex number. |
1662 | |
1663 | The potentially disruptive change is that in list context both methods |
1664 | now I<return the parameter hash>, instead of only the value of the |
1665 | C<"style"> parameter. |
1666 | |
b7d8191e |
1667 | =item Math::Trig |
1668 | |
14218588 |
1669 | A little bit of radial trigonometry (cylindrical and spherical), |
1670 | radial coordinate conversions, and the great circle distance were added. |
b7d8191e |
1671 | |
1761cee5 |
1672 | =item Pod::Parser, Pod::InputObjects |
d4629d6a |
1673 | |
1761cee5 |
1674 | Pod::Parser is a base class for parsing and selecting sections of |
1675 | pod documentation from an input stream. This module takes care of |
1676 | identifying pod paragraphs and commands in the input and hands off the |
1677 | parsed paragraphs and commands to user-defined methods which are free |
1678 | to interpret or translate them as they see fit. |
d4629d6a |
1679 | |
1680 | Pod::InputObjects defines some input objects needed by Pod::Parser, and |
1681 | for advanced users of Pod::Parser that need more about a command besides |
1761cee5 |
1682 | its name and text. |
d4629d6a |
1683 | |
21bad921 |
1684 | As of release 5.6.0 of Perl, Pod::Parser is now the officially sanctioned |
d4629d6a |
1685 | "base parser code" recommended for use by all pod2xxx translators. |
1686 | Pod::Text (pod2text) and Pod::Man (pod2man) have already been converted |
1761cee5 |
1687 | to use Pod::Parser and efforts to convert Pod::HTML (pod2html) are already |
1688 | underway. For any questions or comments about pod parsing and translating |
1689 | issues and utilities, please use the pod-people@perl.org mailing list. |
d4629d6a |
1690 | |
1761cee5 |
1691 | For further information, please see L<Pod::Parser> and L<Pod::InputObjects>. |
d4629d6a |
1692 | |
1761cee5 |
1693 | =item Pod::Checker, podchecker |
d4629d6a |
1694 | |
1761cee5 |
1695 | This utility checks pod files for correct syntax, according to |
1696 | L<perlpod>. Obvious errors are flagged as such, while warnings are |
1697 | printed for mistakes that can be handled gracefully. The checklist is |
1698 | not complete yet. See L<Pod::Checker>. |
d4629d6a |
1699 | |
1761cee5 |
1700 | =item Pod::ParseUtils, Pod::Find |
d4629d6a |
1701 | |
1761cee5 |
1702 | These modules provide a set of gizmos that are useful mainly for pod |
1703 | translators. L<Pod::Find|Pod::Find> traverses directory structures and |
1704 | returns found pod files, along with their canonical names (like |
1705 | C<File::Spec::Unix>). L<Pod::ParseUtils|Pod::ParseUtils> contains |
1706 | B<Pod::List> (useful for storing pod list information), B<Pod::Hyperlink> |
c47ff5f1 |
1707 | (for parsing the contents of C<LE<lt>E<gt>> sequences) and B<Pod::Cache> |
642f9deb |
1708 | (for caching information about pod files, e.g., link nodes). |
d4629d6a |
1709 | |
1761cee5 |
1710 | =item Pod::Select, podselect |
d4629d6a |
1711 | |
1761cee5 |
1712 | Pod::Select is a subclass of Pod::Parser which provides a function |
1713 | named "podselect()" to filter out user-specified sections of raw pod |
1714 | documentation from an input stream. podselect is a script that provides |
1715 | access to Pod::Select from other scripts to be used as a filter. |
1716 | See L<Pod::Select>. |
d4629d6a |
1717 | |
1761cee5 |
1718 | =item Pod::Usage, pod2usage |
d4629d6a |
1719 | |
1761cee5 |
1720 | Pod::Usage provides the function "pod2usage()" to print usage messages for |
1721 | a Perl script based on its embedded pod documentation. The pod2usage() |
1722 | function is generally useful to all script authors since it lets them |
1723 | write and maintain a single source (the pods) for documentation, thus |
1724 | removing the need to create and maintain redundant usage message text |
1725 | consisting of information already in the pods. |
d4629d6a |
1726 | |
1761cee5 |
1727 | There is also a pod2usage script which can be used from other kinds of |
1728 | scripts to print usage messages from pods (even for non-Perl scripts |
1729 | with pods embedded in comments). |
a5222a85 |
1730 | |
1761cee5 |
1731 | For details and examples, please see L<Pod::Usage>. |
a5222a85 |
1732 | |
1733 | =item Pod::Text and Pod::Man |
1734 | |
e3e5e1ea |
1735 | Pod::Text has been rewritten to use Pod::Parser. While pod2text() is |
1736 | still available for backwards compatibility, the module now has a new |
1737 | preferred interface. See L<Pod::Text> for the details. The new Pod::Text |
1738 | module is easily subclassed for tweaks to the output, and two such |
1739 | subclasses (Pod::Text::Termcap for man-page-style bold and underlining |
1740 | using termcap information, and Pod::Text::Color for markup with ANSI color |
1741 | sequences) are now standard. |
1742 | |
1743 | pod2man has been turned into a module, Pod::Man, which also uses |
1744 | Pod::Parser. In the process, several outstanding bugs related to quotes |
1745 | in section headers, quoting of code escapes, and nested lists have been |
1746 | fixed. pod2man is now a wrapper script around this module. |
a5222a85 |
1747 | |
f4b9d880 |
1748 | =item SDBM_File |
1749 | |
1750 | An EXISTS method has been added to this module (and sdbm_exists() has |
1751 | been added to the underlying sdbm library), so one can now call exists |
14218588 |
1752 | on an SDBM_File tied hash and get the correct result, rather than a |
f4b9d880 |
1753 | runtime error. |
1754 | |
a5222a85 |
1755 | A bug that may have caused data loss when more than one disk block |
1756 | happens to be read from the database in a single FETCH() has been |
1757 | fixed. |
1758 | |
8ce86de8 |
1759 | =item Sys::Syslog |
1760 | |
1761 | Sys::Syslog now uses XSUBs to access facilities from syslog.h so it |
1762 | no longer requires syslog.ph to exist. |
1763 | |
f91101c9 |
1764 | =item Sys::Hostname |
1765 | |
1766 | Sys::Hostname now uses XSUBs to call the C library's gethostname() or |
1767 | uname() if they exist. |
1768 | |
e3e5e1ea |
1769 | =item Term::ANSIColor |
1770 | |
1771 | Term::ANSIColor is a very simple module to provide easy and readable |
1772 | access to the ANSI color and highlighting escape sequences, supported by |
1773 | most ANSI terminal emulators. It is now included standard. |
1774 | |
06ef4121 |
1775 | =item Time::Local |
1776 | |
1777 | The timelocal() and timegm() functions used to silently return bogus |
437784d6 |
1778 | results when the date fell outside the machine's integer range. They |
a5222a85 |
1779 | now consistently croak() if the date falls in an unsupported range. |
06ef4121 |
1780 | |
8fe0a5c4 |
1781 | =item Win32 |
1782 | |
1783 | The error return value in list context has been changed for all functions |
14218588 |
1784 | that return a list of values. Previously these functions returned a list |
1785 | with a single element C<undef> if an error occurred. Now these functions |
1786 | return the empty list in these situations. This applies to the following |
8fe0a5c4 |
1787 | functions: |
1788 | |
14218588 |
1789 | Win32::FsType |
1790 | Win32::GetOSVersion |
8fe0a5c4 |
1791 | |
1792 | The remaining functions are unchanged and continue to return C<undef> on |
1793 | error even in list context. |
1794 | |
1795 | The Win32::SetLastError(ERROR) function has been added as a complement |
1796 | to the Win32::GetLastError() function. |
1797 | |
1798 | The new Win32::GetFullPathName(FILENAME) returns the full absolute |
14218588 |
1799 | pathname for FILENAME in scalar context. In list context it returns |
1800 | a two-element list containing the fully qualified directory name and |
501fbaef |
1801 | the filename. See L<Win32>. |
8fe0a5c4 |
1802 | |
9fe6733a |
1803 | =item DBM Filters |
1804 | |
1805 | A new feature called "DBM Filters" has been added to all the |
14218588 |
1806 | DBM modules--DB_File, GDBM_File, NDBM_File, ODBM_File, and SDBM_File. |
1807 | DBM Filters add four new methods to each DBM module: |
9fe6733a |
1808 | |
1809 | filter_store_key |
1810 | filter_store_value |
1811 | filter_fetch_key |
1812 | filter_fetch_value |
1813 | |
14218588 |
1814 | These can be used to filter key-value pairs before the pairs are |
9fe6733a |
1815 | written to the database or just after they are read from the database. |
1816 | See L<perldbmfilter> for further information. |
1817 | |
b7d8191e |
1818 | =back |
3e8c4fa0 |
1819 | |
1820 | =head2 Pragmata |
1821 | |
437784d6 |
1822 | C<use attrs> is now obsolete, and is only provided for |
09bef843 |
1823 | backward-compatibility. It's been replaced by the C<sub : attributes> |
1824 | syntax. See L<perlsub/"Subroutine Attributes"> and L<attributes>. |
1825 | |
4438c4b7 |
1826 | Lexical warnings pragma, C<use warnings;>, to control optional warnings. |
a5222a85 |
1827 | See L<perllexwarn>. |
6c67e1bb |
1828 | |
67d3893f |
1829 | C<use filetest> to control the behaviour of filetests (C<-r> C<-w> |
1830 | ...). Currently only one subpragma implemented, "use filetest |
1831 | 'access';", that uses access(2) or equivalent to check permissions |
1832 | instead of using stat(2) as usual. This matters in filesystems |
1833 | where there are ACLs (access control lists): the stat(2) might lie, |
1834 | but access(2) knows better. |
6c67e1bb |
1835 | |
ba8251e8 |
1836 | =head1 Utility Changes |
1837 | |
a5222a85 |
1838 | =head2 perlcc |
1839 | |
1840 | C<perlcc> now supports the C and Bytecode backends. By default, |
1841 | it generates output from the simple C backend rather than the |
1842 | optimized C backend. |
1843 | |
1844 | Support for non-Unix platforms has been improved. |
1845 | |
ba8251e8 |
1846 | =head1 Documentation Changes |
1847 | |
5fdc711f |
1848 | =over 4 |
1849 | |
954c1994 |
1850 | =item perlapi.pod |
1851 | |
1852 | The official list of public Perl API functions. |
1853 | |
883d36a6 |
1854 | =item perlcompile.pod |
1855 | |
1856 | An introduction to using the Perl Compiler suite. |
1857 | |
c7c04614 |
1858 | =item perlfilter.pod |
1859 | |
1860 | An introduction to writing Perl source filters. |
1861 | |
883d36a6 |
1862 | =item perlhack.pod |
1863 | |
1864 | Some guidelines for hacking the Perl source code. |
1865 | |
954c1994 |
1866 | =item perlintern.pod |
1867 | |
1868 | A list of internal functions in the Perl source code. |
1869 | (List is currently empty.) |
1870 | |
5fdc711f |
1871 | =item perlopentut.pod |
f8284313 |
1872 | |
5fdc711f |
1873 | A tutorial on using open() effectively. |
1874 | |
1875 | =item perlreftut.pod |
1876 | |
1877 | A tutorial that introduces the essentials of references. |
1878 | |
694468e3 |
1879 | =item perlboot.pod |
1880 | |
1881 | A tutorial for beginners on object-oriented Perl. |
1882 | |
14218588 |
1883 | =item perltootc.pod |
1884 | |
1885 | A tutorial on managing class data for object modules. |
1886 | |
393fec97 |
1887 | =item perlunicode.pod |
1888 | |
1889 | An introduction to Unicode support features in Perl. |
1890 | |
5fdc711f |
1891 | =back |
e02fdbd2 |
1892 | |
73b437c8 |
1893 | =head1 New or Changed Diagnostics |
ba8251e8 |
1894 | |
a99ba403 |
1895 | =over 4 |
1896 | |
56e90b21 |
1897 | =item "%s" variable %s masks earlier declaration in same %s |
1898 | |
1899 | (W) A "my" or "our" variable has been redeclared in the current scope or statement, |
1900 | effectively eliminating all access to the previous instance. This is almost |
1901 | always a typographical error. Note that the earlier variable will still exist |
1902 | until the end of the scope or until all closure referents to it are |
1903 | destroyed. |
1904 | |
33633739 |
1905 | =item "my sub" not yet implemented |
1906 | |
1907 | (F) Lexically scoped subroutines are not yet implemented. Don't try that |
1908 | yet. |
1909 | |
1910 | =item "our" variable %s redeclared |
1911 | |
1912 | (W) You seem to have already declared the same global once before in the |
1913 | current lexical scope. |
1914 | |
a99ba403 |
1915 | =item '!' allowed only after types %s |
1916 | |
1917 | (F) The '!' is allowed in pack() and unpack() only after certain types. |
1918 | See L<perlfunc/pack>. |
1919 | |
1920 | =item / cannot take a count |
1921 | |
1922 | (F) You had an unpack template indicating a counted-length string, |
1923 | but you have also specified an explicit size for the string. |
1924 | See L<perlfunc/pack>. |
1925 | |
1926 | =item / must be followed by a, A or Z |
1927 | |
1928 | (F) You had an unpack template indicating a counted-length string, |
1929 | which must be followed by one of the letters a, A or Z |
1930 | to indicate what sort of string is to be unpacked. |
1931 | See L<perlfunc/pack>. |
1932 | |
1933 | =item / must be followed by a*, A* or Z* |
1934 | |
437784d6 |
1935 | (F) You had a pack template indicating a counted-length string, |
a99ba403 |
1936 | Currently the only things that can have their length counted are a*, A* or Z*. |
1937 | See L<perlfunc/pack>. |
1938 | |
1939 | =item / must follow a numeric type |
1940 | |
1941 | (F) You had an unpack template that contained a '#', |
1942 | but this did not follow some numeric unpack specification. |
1943 | See L<perlfunc/pack>. |
1944 | |
a99ba403 |
1945 | =item /%s/: Unrecognized escape \\%c passed through |
1946 | |
1947 | (W) You used a backslash-character combination which is not recognized |
1948 | by Perl. This combination appears in an interpolated variable or a |
1028017a |
1949 | C<'>-delimited regular expression. The character was understood literally. |
1950 | |
1951 | =item /%s/: Unrecognized escape \\%c in character class passed through |
1952 | |
1953 | (W) You used a backslash-character combination which is not recognized |
1954 | by Perl inside character classes. The character was understood literally. |
a99ba403 |
1955 | |
1956 | =item /%s/ should probably be written as "%s" |
1957 | |
1958 | (W) You have used a pattern where Perl expected to find a string, |
437784d6 |
1959 | as in the first argument to C<join>. Perl will treat the true |
a99ba403 |
1960 | or false result of matching the pattern against $_ as the string, |
1961 | which is probably not what you had in mind. |
1962 | |
1963 | =item %s() called too early to check prototype |
1964 | |
1965 | (W) You've called a function that has a prototype before the parser saw a |
1966 | definition or declaration for it, and Perl could not check that the call |
1967 | conforms to the prototype. You need to either add an early prototype |
1968 | declaration for the subroutine in question, or move the subroutine |
1969 | definition ahead of the call to get proper prototype checking. Alternatively, |
1970 | if you are certain that you're calling the function correctly, you may put |
1971 | an ampersand before the name to avoid the warning. See L<perlsub>. |
1972 | |
56e90b21 |
1973 | =item %s argument is not a HASH or ARRAY element |
1974 | |
1975 | (F) The argument to exists() must be a hash or array element, such as: |
1976 | |
1977 | $foo{$bar} |
1978 | $ref->[12]->["susie"] |
1979 | |
1980 | =item %s argument is not a HASH or ARRAY element or slice |
1981 | |
1982 | (F) The argument to delete() must be either a hash or array element, such as: |
1983 | |
1984 | $foo{$bar} |
1985 | $ref->[12]->["susie"] |
1986 | |
1987 | or a hash or array slice, such as: |
1988 | |
1989 | @foo[$bar, $baz, $xyzzy] |
1990 | @{$ref->[12]}{"susie", "queue"} |
1991 | |
afebc493 |
1992 | =item %s argument is not a subroutine name |
1993 | |
1994 | (F) The argument to exists() for C<exists &sub> must be a subroutine |
1995 | name, and not a subroutine call. C<exists &sub()> will generate this error. |
1996 | |
09bef843 |
1997 | =item %s package attribute may clash with future reserved word: %s |
1998 | |
1999 | (W) A lowercase attribute name was used that had a package-specific handler. |
2000 | That name might have a meaning to Perl itself some day, even though it |
2001 | doesn't yet. Perhaps you should use a mixed-case attribute name, instead. |
2002 | See L<attributes>. |
2003 | |
a99ba403 |
2004 | =item (in cleanup) %s |
6b121555 |
2005 | |
a99ba403 |
2006 | (W) This prefix usually indicates that a DESTROY() method raised |
2007 | the indicated exception. Since destructors are usually called by |
2008 | the system at arbitrary points during execution, and often a vast |
2009 | number of times, the warning is issued only once for any number |
2010 | of failures that would otherwise result in the same message being |
2011 | repeated. |
2012 | |
2013 | Failure of user callbacks dispatched using the C<G_KEEPERR> flag |
2014 | could also result in this warning. See L<perlcall/G_KEEPERR>. |
2015 | |
2016 | =item <> should be quotes |
2017 | |
c47ff5f1 |
2018 | (F) You wrote C<< require <file> >> when you should have written |
a99ba403 |
2019 | C<require 'file'>. |
2020 | |
2021 | =item Attempt to join self |
2022 | |
2023 | (F) You tried to join a thread from within itself, which is an |
2024 | impossible task. You may be joining the wrong thread, or you may |
2025 | need to move the join() to some other thread. |
2026 | |
2027 | =item Bad evalled substitution pattern |
2028 | |
2029 | (F) You've used the /e switch to evaluate the replacement for a |
2030 | substitution, but perl found a syntax error in the code to evaluate, |
2031 | most likely an unexpected right brace '}'. |
2032 | |
2033 | =item Bad realloc() ignored |
2034 | |
2035 | (S) An internal routine called realloc() on something that had never been |
2036 | malloc()ed in the first place. Mandatory, but can be disabled by |
2037 | setting environment variable C<PERL_BADFREE> to 1. |
2038 | |
34d09196 |
2039 | =item Bareword found in conditional |
2040 | |
2041 | (W) The compiler found a bareword where it expected a conditional, |
2042 | which often indicates that an || or && was parsed as part of the |
2043 | last argument of the previous construct, for example: |
2044 | |
2045 | open FOO || die; |
2046 | |
2047 | It may also indicate a misspelled constant that has been interpreted |
2048 | as a bareword: |
2049 | |
2050 | use constant TYPO => 1; |
2051 | if (TYOP) { print "foo" } |
2052 | |
2053 | The C<strict> pragma is useful in avoiding such errors. |
2054 | |
a99ba403 |
2055 | =item Binary number > 0b11111111111111111111111111111111 non-portable |
2056 | |
2057 | (W) The binary number you specified is larger than 2**32-1 |
2058 | (4294967295) and therefore non-portable between systems. See |
2059 | L<perlport> for more on portability concerns. |
2060 | |
2061 | =item Bit vector size > 32 non-portable |
2062 | |
2063 | (W) Using bit vector sizes larger than 32 is non-portable. |
2064 | |
2065 | =item Buffer overflow in prime_env_iter: %s |
2066 | |
2067 | (W) A warning peculiar to VMS. While Perl was preparing to iterate over |
2068 | %ENV, it encountered a logical name or symbol definition which was too long, |
2069 | so it was truncated to the string shown. |
2070 | |
2071 | =item Can't check filesystem of script "%s" |
2072 | |
2073 | (P) For some reason you can't check the filesystem of the script for nosuid. |
2074 | |
56e90b21 |
2075 | =item Can't declare class for non-scalar %s in "%s" |
2076 | |
2077 | (S) Currently, only scalar variables can declared with a specific class |
2078 | qualifier in a "my" or "our" declaration. The semantics may be extended |
2079 | for other types of variables in future. |
2080 | |
2081 | =item Can't declare %s in "%s" |
2082 | |
2083 | (F) Only scalar, array, and hash variables may be declared as "my" or |
2084 | "our" variables. They must have ordinary identifiers as names. |
2085 | |
0b5b802d |
2086 | =item Can't ignore signal CHLD, forcing to default |
2087 | |
2088 | (W) Perl has detected that it is being run with the SIGCHLD signal |
2089 | (sometimes known as SIGCLD) disabled. Since disabling this signal |
2090 | will interfere with proper determination of exit status of child |
2091 | processes, Perl has reset the signal to its default value. |
2092 | This situation typically indicates that the parent program under |
642f9deb |
2093 | which Perl may be running (e.g., cron) is being very careless. |
0b5b802d |
2094 | |
a99ba403 |
2095 | =item Can't modify non-lvalue subroutine call |
2096 | |
437784d6 |
2097 | (F) Subroutines meant to be used in lvalue context should be declared as |
2098 | such, see L<perlsub/"Lvalue subroutines">. |
a99ba403 |
2099 | |
2100 | =item Can't read CRTL environ |
2101 | |
2102 | (S) A warning peculiar to VMS. Perl tried to read an element of %ENV |
2103 | from the CRTL's internal environment array and discovered the array was |
2104 | missing. You need to figure out where your CRTL misplaced its environ |
2105 | or define F<PERL_ENV_TABLES> (see L<perlvms>) so that environ is not searched. |
2106 | |
2107 | =item Can't remove %s: %s, skipping file |
2108 | |
2109 | (S) You requested an inplace edit without creating a backup file. Perl |
2110 | was unable to remove the original file to replace it with the modified |
2111 | file. The file was left unmodified. |
2112 | |
2113 | =item Can't return %s from lvalue subroutine |
2114 | |
2115 | (F) Perl detected an attempt to return illegal lvalues (such |
2116 | as temporary or readonly values) from a subroutine used as an lvalue. |
2117 | This is not allowed. |
2118 | |
2119 | =item Can't weaken a nonreference |
2120 | |
2121 | (F) You attempted to weaken something that was not a reference. Only |
2122 | references can be weakened. |
2123 | |
2124 | =item Character class [:%s:] unknown |
2125 | |
2126 | (F) The class in the character class [: :] syntax is unknown. |
437784d6 |
2127 | See L<perlre>. |
a99ba403 |
2128 | |
2129 | =item Character class syntax [%s] belongs inside character classes |
2130 | |
2131 | (W) The character class constructs [: :], [= =], and [. .] go |
2132 | I<inside> character classes, the [] are part of the construct, |
437784d6 |
2133 | for example: /[012[:alpha:]345]/. Note that [= =] and [. .] |
2134 | are not currently implemented; they are simply placeholders for |
2135 | future extensions. |
a99ba403 |
2136 | |
2137 | =item Constant is not %s reference |
2138 | |
2139 | (F) A constant value (perhaps declared using the C<use constant> pragma) |
2140 | is being dereferenced, but it amounts to the wrong type of reference. The |
2141 | message indicates the type of reference that was expected. This usually |
2142 | indicates a syntax error in dereferencing the constant value. |
2143 | See L<perlsub/"Constant Functions"> and L<constant>. |
2144 | |
2145 | =item constant(%s): %%^H is not localized |
2146 | |
2147 | (F) When setting compile-time-lexicalized hash %^H one should set the |
2148 | corresponding bit of $^H as well. |
2149 | |
2150 | =item constant(%s): %s |
2151 | |
2152 | (F) Compile-time-substitutions (such as overloaded constants and |
2153 | character names) were not correctly set up. |
2154 | |
2155 | =item defined(@array) is deprecated |
2156 | |
2157 | (D) defined() is not usually useful on arrays because it checks for an |
2158 | undefined I<scalar> value. If you want to see if the array is empty, |
2159 | just use C<if (@array) { # not empty }> for example. |
2160 | |
2161 | =item defined(%hash) is deprecated |
2162 | |
2163 | (D) defined() is not usually useful on hashes because it checks for an |
2164 | undefined I<scalar> value. If you want to see if the hash is empty, |
2165 | just use C<if (%hash) { # not empty }> for example. |
2166 | |
2167 | =item Did not produce a valid header |
2168 | |
2169 | See Server error. |
2170 | |
33633739 |
2171 | =item Did you mean "local" instead of "our"? |
2172 | |
2173 | (W) Remember that "our" does not localize the declared global variable. |
2174 | You have declared it again in the same lexical scope, which seems superfluous. |
2175 | |
a99ba403 |
2176 | =item Document contains no data |
2177 | |
2178 | See Server error. |
2179 | |
2180 | =item entering effective %s failed |
2181 | |
2182 | (F) While under the C<use filetest> pragma, switching the real and |
2183 | effective uids or gids failed. |
6b121555 |
2184 | |
73b437c8 |
2185 | =item false [] range "%s" in regexp |
2186 | |
2187 | (W) A character class range must start and end at a literal character, not |
2188 | another character class like C<\d> or C<[:alpha:]>. The "-" in your false |
2189 | range is interpreted as a literal "-". Consider quoting the "-", "\-". |
2190 | See L<perlre>. |
2191 | |
af8c498a |
2192 | =item Filehandle %s opened only for output |
6b121555 |
2193 | |
af8c498a |
2194 | (W) You tried to read from a filehandle opened only for writing. If you |
437784d6 |
2195 | intended it to be a read/write filehandle, you needed to open it with |
c47ff5f1 |
2196 | "+<" or "+>" or "+>>" instead of with "<" or nothing. If |
2197 | you intended only to read from the file, use "<". See |
af8c498a |
2198 | L<perlfunc/open>. |
e02fdbd2 |
2199 | |
56e90b21 |
2200 | =item flock() on closed filehandle %s |
2201 | |
2202 | (W) The filehandle you're attempting to flock() got itself closed some |
2203 | time before now. Check your logic flow. flock() operates on filehandles. |
2204 | Are you attempting to call flock() on a dirhandle by the same name? |
2205 | |
2206 | =item Global symbol "%s" requires explicit package name |
2207 | |
2208 | (F) You've said "use strict vars", which indicates that all variables |
2209 | must either be lexically scoped (using "my"), declared beforehand using |
2210 | "our", or explicitly qualified to say which package the global variable |
2211 | is in (using "::"). |
2212 | |
a99ba403 |
2213 | =item Hexadecimal number > 0xffffffff non-portable |
2214 | |
2215 | (W) The hexadecimal number you specified is larger than 2**32-1 |
2216 | (4294967295) and therefore non-portable between systems. See |
2217 | L<perlport> for more on portability concerns. |
2218 | |
2219 | =item Ill-formed CRTL environ value "%s" |
2220 | |
2221 | (W) A warning peculiar to VMS. Perl tried to read the CRTL's internal |
2222 | environ array, and encountered an element without the C<=> delimiter |
2223 | used to spearate keys from values. The element is ignored. |
2224 | |
2225 | =item Ill-formed message in prime_env_iter: |%s| |
2226 | |
2227 | (W) A warning peculiar to VMS. Perl tried to read a logical name |
2228 | or CLI symbol definition when preparing to iterate over %ENV, and |
2229 | didn't see the expected delimiter between key and value, so the |
2230 | line was ignored. |
2231 | |
2232 | =item Illegal binary digit %s |
2233 | |
437784d6 |
2234 | (F) You used a digit other than 0 or 1 in a binary number. |
a99ba403 |
2235 | |
2236 | =item Illegal binary digit %s ignored |
2237 | |
2238 | (W) You may have tried to use a digit other than 0 or 1 in a binary number. |
2239 | Interpretation of the binary number stopped before the offending digit. |
2240 | |
2241 | =item Illegal number of bits in vec |
2242 | |
2243 | (F) The number of bits in vec() (the third argument) must be a power of |
2244 | two from 1 to 32 (or 64, if your platform supports that). |
2245 | |
2246 | =item Integer overflow in %s number |
2247 | |
2248 | (W) The hexadecimal, octal or binary number you have specified either |
c6edd1b7 |
2249 | as a literal or as an argument to hex() or oct() is too big for your |
a99ba403 |
2250 | architecture, and has been converted to a floating point number. On a |
2251 | 32-bit architecture the largest hexadecimal, octal or binary number |
2252 | representable without overflow is 0xFFFFFFFF, 037777777777, or |
2253 | 0b11111111111111111111111111111111 respectively. Note that Perl |
2254 | transparently promotes all numbers to a floating point representation |
2255 | internally--subject to loss of precision errors in subsequent |
2256 | operations. |
2257 | |
09bef843 |
2258 | =item Invalid %s attribute: %s |
2259 | |
2260 | The indicated attribute for a subroutine or variable was not recognized |
2261 | by Perl or by a user-supplied handler. See L<attributes>. |
2262 | |
2263 | =item Invalid %s attributes: %s |
2264 | |
2265 | The indicated attributes for a subroutine or variable were not recognized |
2266 | by Perl or by a user-supplied handler. See L<attributes>. |
2267 | |
73b437c8 |
2268 | =item invalid [] range "%s" in regexp |
2269 | |
2270 | The offending range is now explicitly displayed. |
2271 | |
09bef843 |
2272 | =item Invalid separator character %s in attribute list |
2273 | |
0120eecf |
2274 | (F) Something other than a colon or whitespace was seen between the |
09bef843 |
2275 | elements of an attribute list. If the previous attribute |
2276 | had a parenthesised parameter list, perhaps that list was terminated |
2277 | too soon. See L<attributes>. |
2278 | |
a99ba403 |
2279 | =item Invalid separator character %s in subroutine attribute list |
2280 | |
0120eecf |
2281 | (F) Something other than a colon or whitespace was seen between the |
a99ba403 |
2282 | elements of a subroutine attribute list. If the previous attribute |
2283 | had a parenthesised parameter list, perhaps that list was terminated |
2284 | too soon. |
2285 | |
2286 | =item leaving effective %s failed |
2287 | |
2288 | (F) While under the C<use filetest> pragma, switching the real and |
2289 | effective uids or gids failed. |
2290 | |
2291 | =item Lvalue subs returning %s not implemented yet |
2292 | |
2293 | (F) Due to limitations in the current implementation, array and hash |
2294 | values cannot be returned in subroutines used in lvalue context. |
2295 | See L<perlsub/"Lvalue subroutines">. |
2296 | |
2297 | =item Method %s not permitted |
2298 | |
2299 | See Server error. |
2300 | |
2301 | =item Missing %sbrace%s on \N{} |
2302 | |
2303 | (F) Wrong syntax of character name literal C<\N{charname}> within |
2304 | double-quotish context. |
2305 | |
06eaf0bc |
2306 | =item Missing command in piped open |
2307 | |
2308 | (W) You used the C<open(FH, "| command")> or C<open(FH, "command |")> |
2309 | construction, but the command was missing or blank. |
2310 | |
09bef843 |
2311 | =item Missing name in "my sub" |
2312 | |
2313 | (F) The reserved syntax for lexically scoped subroutines requires that they |
2314 | have a name with which they can be found. |
2315 | |
56e90b21 |
2316 | =item No %s specified for -%c |
2317 | |
2318 | (F) The indicated command line switch needs a mandatory argument, but |
2319 | you haven't specified one. |
2320 | |
2321 | =item No package name allowed for variable %s in "our" |
2322 | |
2323 | (F) Fully qualified variable names are not allowed in "our" declarations, |
2324 | because that doesn't make much sense under existing semantics. Such |
2325 | syntax is reserved for future extensions. |
2326 | |
2327 | =item No space allowed after -%c |
2328 | |
2329 | (F) The argument to the indicated command line switch must follow immediately |
2330 | after the switch, without intervening spaces. |
2331 | |
a99ba403 |
2332 | =item no UTC offset information; assuming local time is UTC |
2333 | |
2334 | (S) A warning peculiar to VMS. Perl was unable to find the local |
2335 | timezone offset, so it's assuming that local system time is equivalent |
2336 | to UTC. If it's not, define the logical name F<SYS$TIMEZONE_DIFFERENTIAL> |
2337 | to translate to the number of seconds which need to be added to UTC to |
2338 | get local time. |
2339 | |
2340 | =item Octal number > 037777777777 non-portable |
2341 | |
2342 | (W) The octal number you specified is larger than 2**32-1 (4294967295) |
2343 | and therefore non-portable between systems. See L<perlport> for more |
2344 | on portability concerns. |
2345 | |
2346 | See also L<perlport> for writing portable code. |
2347 | |
2348 | =item panic: del_backref |
2349 | |
2350 | (P) Failed an internal consistency check while trying to reset a weak |
2351 | reference. |
2352 | |
2353 | =item panic: kid popen errno read |
2354 | |
2355 | (F) forked child returned an incomprehensible message about its errno. |
2356 | |
2357 | =item panic: magic_killbackrefs |
2358 | |
2359 | (P) Failed an internal consistency check while trying to reset all weak |
2360 | references to an object. |
2361 | |
56e90b21 |
2362 | =item Parentheses missing around "%s" list |
2363 | |
2364 | (W) You said something like |
2365 | |
2366 | my $foo, $bar = @_; |
2367 | |
2368 | when you meant |
2369 | |
2370 | my ($foo, $bar) = @_; |
2371 | |
54884818 |
2372 | Remember that "my", "our", and "local" bind tighter than comma. |
56e90b21 |
2373 | |
a99ba403 |
2374 | =item Possible Y2K bug: %s |
2375 | |
2376 | (W) You are concatenating the number 19 with another number, which |
2377 | could be a potential Year 2000 problem. |
2378 | |
2379 | =item Premature end of script headers |
2380 | |
2381 | See Server error. |
2382 | |
0b5b802d |
2383 | =item Repeat count in pack overflows |
2384 | |
2385 | (F) You can't specify a repeat count so large that it overflows |
2386 | your signed integers. See L<perlfunc/pack>. |
2387 | |
2388 | =item Repeat count in unpack overflows |
2389 | |
2390 | (F) You can't specify a repeat count so large that it overflows |
2391 | your signed integers. See L<perlfunc/unpack>. |
2392 | |
a99ba403 |
2393 | =item realloc() of freed memory ignored |
2394 | |
2395 | (S) An internal routine called realloc() on something that had already |
2396 | been freed. |
2397 | |
2398 | =item Reference is already weak |
2399 | |
2400 | (W) You have attempted to weaken a reference that is already weak. |
2401 | Doing so has no effect. |
2402 | |
2403 | =item setpgrp can't take arguments |
2404 | |
2405 | (F) Your system has the setpgrp() from BSD 4.2, which takes no arguments, |
2406 | unlike POSIX setpgid(), which takes a process ID and process group ID. |
2407 | |
2408 | =item Strange *+?{} on zero-length expression |
2409 | |
2410 | (W) You applied a regular expression quantifier in a place where it |
2411 | makes no sense, such as on a zero-width assertion. |
2412 | Try putting the quantifier inside the assertion instead. For example, |
2413 | the way to match "abc" provided that it is followed by three |
2414 | repetitions of "xyz" is C</abc(?=(?:xyz){3})/>, not C</abc(?=xyz){3}/>. |
2415 | |
2416 | =item switching effective %s is not implemented |
2417 | |
2418 | (F) While under the C<use filetest> pragma, we cannot switch the |
2419 | real and effective uids or gids. |
2420 | |
437784d6 |
2421 | =item This Perl can't reset CRTL environ elements (%s) |
a99ba403 |
2422 | |
2423 | =item This Perl can't set CRTL environ elements (%s=%s) |
2424 | |
2425 | (W) Warnings peculiar to VMS. You tried to change or delete an element |
2426 | of the CRTL's internal environ array, but your copy of Perl wasn't |
2427 | built with a CRTL that contained the setenv() function. You'll need to |
2428 | rebuild Perl with a CRTL that does, or redefine F<PERL_ENV_TABLES> (see |
2429 | L<perlvms>) so that the environ array isn't the target of the change to |
2430 | %ENV which produced the warning. |
2431 | |
2432 | =item Unknown open() mode '%s' |
2433 | |
437784d6 |
2434 | (F) The second argument of 3-argument open() is not among the list |
c47ff5f1 |
2435 | of valid modes: C<< < >>, C<< > >>, C<<< >> >>>, C<< +< >>, |
2436 | C<< +> >>, C<<< +>> >>>, C<-|>, C<|->. |
a99ba403 |
2437 | |
2438 | =item Unknown process %x sent message to prime_env_iter: %s |
2439 | |
2440 | (P) An error peculiar to VMS. Perl was reading values for %ENV before |
2441 | iterating over it, and someone else stuck a message in the stream of |
2442 | data Perl expected. Someone's very confused, or perhaps trying to |
2443 | subvert Perl's population of %ENV for nefarious purposes. |
2444 | |
af8c498a |
2445 | =item Unrecognized escape \\%c passed through |
2446 | |
2447 | (W) You used a backslash-character combination which is not recognized |
1028017a |
2448 | by Perl. The character was understood literally. |
af8c498a |
2449 | |
09bef843 |
2450 | =item Unterminated attribute parameter in attribute list |
2451 | |
2452 | (F) The lexer saw an opening (left) parenthesis character while parsing an |
2453 | attribute list, but the matching closing (right) parenthesis |
2454 | character was not found. You may need to add (or remove) a backslash |
2455 | character to get your parentheses to balance. See L<attributes>. |
2456 | |
2457 | =item Unterminated attribute list |
2458 | |
2459 | (F) The lexer found something other than a simple identifier at the start |
2460 | of an attribute, and it wasn't a semicolon or the start of a |
2461 | block. Perhaps you terminated the parameter list of the previous attribute |
2462 | too soon. See L<attributes>. |
2463 | |
09bef843 |
2464 | =item Unterminated attribute parameter in subroutine attribute list |
2465 | |
2466 | (F) The lexer saw an opening (left) parenthesis character while parsing a |
2467 | subroutine attribute list, but the matching closing (right) parenthesis |
2468 | character was not found. You may need to add (or remove) a backslash |
2469 | character to get your parentheses to balance. |
2470 | |
2471 | =item Unterminated subroutine attribute list |
2472 | |
2473 | (F) The lexer found something other than a simple identifier at the start |
2474 | of a subroutine attribute, and it wasn't a semicolon or the start of a |
2475 | block. Perhaps you terminated the parameter list of the previous attribute |
2476 | too soon. |
2477 | |
a99ba403 |
2478 | =item Value of CLI symbol "%s" too long |
eb6e2d6f |
2479 | |
a99ba403 |
2480 | (W) A warning peculiar to VMS. Perl tried to read the value of an %ENV |
2481 | element from a CLI symbol table, and found a resultant string longer |
2482 | than 1024 characters. The return value has been truncated to 1024 |
2483 | characters. |
eb6e2d6f |
2484 | |
a99ba403 |
2485 | =item Version number must be a constant number |
ba8251e8 |
2486 | |
a99ba403 |
2487 | (P) The attempt to translate a C<use Module n.n LIST> statement into |
2488 | its equivalent C<BEGIN> block found an internal inconsistency with |
2489 | the version number. |
2490 | |
2491 | =back |
27806c82 |
2492 | |
a5222a85 |
2493 | =head1 Obsolete Diagnostics |
3175b8cd |
2494 | |
a99ba403 |
2495 | =over 4 |
2496 | |
2497 | =item Character class syntax [: :] is reserved for future extensions |
2498 | |
2499 | (W) Within regular expression character classes ([]) the syntax beginning |
2500 | with "[:" and ending with ":]" is reserved for future extensions. |
2501 | If you need to represent those character sequences inside a regular |
2502 | expression character class, just quote the square brackets with the |
2503 | backslash: "\[:" and ":\]". |
2504 | |
2505 | =item Ill-formed logical name |%s| in prime_env_iter |
2506 | |
2507 | (W) A warning peculiar to VMS. A logical name was encountered when preparing |
2508 | to iterate over %ENV which violates the syntactic rules governing logical |
2509 | names. Because it cannot be translated normally, it is skipped, and will not |
2510 | appear in %ENV. This may be a benign occurrence, as some software packages |
2511 | might directly modify logical name tables and introduce nonstandard names, |
2512 | or it may indicate that a logical name table has been corrupted. |
2513 | |
34d09196 |
2514 | =item Probable precedence problem on %s |
2515 | |
2516 | (W) The compiler found a bareword where it expected a conditional, |
2517 | which often indicates that an || or && was parsed as part of the |
2518 | last argument of the previous construct, for example: |
2519 | |
2520 | open FOO || die; |
2521 | |
a99ba403 |
2522 | =item regexp too big |
2523 | |
2524 | (F) The current implementation of regular expressions uses shorts as |
2525 | address offsets within a string. Unfortunately this means that if |
2526 | the regular expression compiles to longer than 32767, it'll blow up. |
2527 | Usually when you want a regular expression this big, there is a better |
2528 | way to do it with multiple statements. See L<perlre>. |
2529 | |
2530 | =item Use of "$$<digit>" to mean "${$}<digit>" is deprecated |
2531 | |
2532 | (D) Perl versions before 5.004 misinterpreted any type marker followed |
2533 | by "$" and a digit. For example, "$$0" was incorrectly taken to mean |
2534 | "${$}0" instead of "${$0}". This bug is (mostly) fixed in Perl 5.004. |
2535 | |
2536 | However, the developers of Perl 5.004 could not fix this bug completely, |
2537 | because at least two widely-used modules depend on the old meaning of |
2538 | "$$0" in a string. So Perl 5.004 still interprets "$$<digit>" in the |
2539 | old (broken) way inside strings; but it generates this message as a |
2540 | warning. And in Perl 5.005, this special treatment will cease. |
2541 | |
2542 | =back |
3175b8cd |
2543 | |
ba8251e8 |
2544 | =head1 BUGS |
2545 | |
437784d6 |
2546 | If you find what you think is a bug, you might check the |
14218588 |
2547 | articles recently posted to the comp.lang.perl.misc newsgroup. |
ba8251e8 |
2548 | There may also be information at http://www.perl.com/perl/, the Perl |
2549 | Home Page. |
2550 | |
2551 | If you believe you have an unreported bug, please run the B<perlbug> |
642f9deb |
2552 | program included with your release. Be sure to trim your bug down |
ba8251e8 |
2553 | to a tiny but sufficient test case. Your bug report, along with the |
14218588 |
2554 | output of C<perl -V>, will be sent off to perlbug@perl.com to be |
ba8251e8 |
2555 | analysed by the Perl porting team. |
2556 | |
2557 | =head1 SEE ALSO |
2558 | |
2559 | The F<Changes> file for exhaustive details on what changed. |
2560 | |
2561 | The F<INSTALL> file for how to build Perl. |
2562 | |
2563 | The F<README> file for general stuff. |
2564 | |
2565 | The F<Artistic> and F<Copying> files for copyright information. |
2566 | |
2567 | =head1 HISTORY |
2568 | |
a5222a85 |
2569 | Written by Gurusamy Sarathy <F<gsar@activestate.com>>, with many |
2570 | contributions from The Perl Porters. |
ba8251e8 |
2571 | |
2572 | Send omissions or corrections to <F<perlbug@perl.com>>. |
2573 | |
2574 | =cut |