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1 | =head1 NAME |
2 | |
3 | perltodo - Perl TO-DO List |
4 | |
5 | =head1 DESCRIPTION |
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6 | |
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7 | This is a list of wishes for Perl. The tasks we think are smaller or easier |
8 | are listed first. Anyone is welcome to work on any of these, but it's a good |
9 | idea to first contact I<perl5-porters@perl.org> to avoid duplication of |
10 | effort. By all means contact a pumpking privately first if you prefer. |
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11 | |
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12 | Whilst patches to make the list shorter are most welcome, ideas to add to |
13 | the list are also encouraged. Check the perl5-porters archives for past |
14 | ideas, and any discussion about them. One set of archives may be found at: |
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15 | |
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16 | http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/ |
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17 | |
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18 | What can we offer you in return? Fame, fortune, and everlasting glory? Maybe |
19 | not, but if your patch is incorporated, then we'll add your name to the |
20 | F<AUTHORS> file, which ships in the official distribution. How many other |
21 | programming languages offer you 1 line of immortality? |
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22 | |
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23 | =head1 The roadmap to 5.10 |
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24 | |
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25 | The roadmap to 5.10 envisages feature based releases, as various items in this |
26 | TODO are completed. |
27 | |
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28 | =head2 Needed for a 5.9.5 release |
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29 | |
30 | =over |
31 | |
32 | =item * |
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33 | |
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34 | Implement L</_ prototype character> |
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35 | |
860f190d |
36 | =item * |
37 | |
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38 | Review smart match semantics in light of Perl 6 developments. |
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39 | |
40 | =item * |
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41 | |
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42 | Review assertions. Review syntax to combine assertions. Assertions could take |
43 | advantage of the lexical pragmas work. L</What hooks would assertions need?> |
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44 | |
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45 | =item * |
46 | |
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47 | C<encoding> should be turned into a lexical pragma (probably). |
c1f116f6 |
48 | |
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49 | =back |
50 | |
51 | =head2 Needed for a 5.9.6 release |
52 | |
53 | Stabilisation. If all goes well, this will be the equivalent of a 5.10-beta. |
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54 | |
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55 | =head1 Tasks that only need Perl knowledge |
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56 | |
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57 | =head2 common test code for timed bail out |
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58 | |
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59 | Write portable self destruct code for tests to stop them burning CPU in |
60 | infinite loops. This needs to avoid using alarm, as some of the tests are |
61 | testing alarm/sleep or timers. |
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62 | |
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63 | =head2 POD -> HTML conversion in the core still sucks |
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64 | |
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65 | Which is crazy given just how simple POD purports to be, and how simple HTML |
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66 | can be. It's not actually I<as> simple as it sounds, particularly with the |
67 | flexibility POD allows for C<=item>, but it would be good to improve the |
68 | visual appeal of the HTML generated, and to avoid it having any validation |
69 | errors. See also L</make HTML install work>, as the layout of installation tree |
70 | is needed to improve the cross-linking. |
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71 | |
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72 | The addition of C<Pod::Simple> and its related modules may make this task |
73 | easier to complete. |
74 | |
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75 | =head2 Parallel testing |
76 | |
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77 | (This probably impacts much more than the core: also the Test::Harness |
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78 | and TAP::* modules on CPAN.) |
79 | |
aa237293 |
80 | The core regression test suite is getting ever more comprehensive, which has |
81 | the side effect that it takes longer to run. This isn't so good. Investigate |
82 | whether it would be feasible to give the harness script the B<option> of |
83 | running sets of tests in parallel. This would be useful for tests in |
84 | F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>. |
85 | |
86 | Questions to answer |
87 | |
88 | =over 4 |
89 | |
90 | =item 1 |
91 | |
92 | How does screen layout work when you're running more than one test? |
93 | |
94 | =item 2 |
95 | |
96 | How does the caller of test specify how many tests to run in parallel? |
97 | |
98 | =item 3 |
99 | |
100 | How do setup/teardown tests identify themselves? |
101 | |
102 | =back |
103 | |
104 | Pugs already does parallel testing - can their approach be re-used? |
105 | |
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106 | =head2 Make Schwern poorer |
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107 | |
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108 | We should have tests for everything. When all the core's modules are tested, |
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109 | Schwern has promised to donate to $500 to TPF. We may need volunteers to |
110 | hold him upside down and shake vigorously in order to actually extract the |
111 | cash. |
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112 | |
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113 | =head2 Improve the coverage of the core tests |
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114 | |
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115 | Use Devel::Cover to ascertain the core modules's test coverage, then add |
116 | tests that are currently missing. |
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117 | |
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118 | =head2 test B |
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119 | |
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120 | A full test suite for the B module would be nice. |
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121 | |
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122 | =head2 A decent benchmark |
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123 | |
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124 | C<perlbench> seems impervious to any recent changes made to the perl core. It |
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125 | would be useful to have a reasonable general benchmarking suite that roughly |
126 | represented what current perl programs do, and measurably reported whether |
127 | tweaks to the core improve, degrade or don't really affect performance, to |
128 | guide people attempting to optimise the guts of perl. Gisle would welcome |
129 | new tests for perlbench. |
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130 | |
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131 | =head2 fix tainting bugs |
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132 | |
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133 | Fix the bugs revealed by running the test suite with the C<-t> switch (via |
134 | C<make test.taintwarn>). |
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135 | |
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136 | =head2 Dual life everything |
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137 | |
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138 | As part of the "dists" plan, anything that doesn't belong in the smallest perl |
139 | distribution needs to be dual lifed. Anything else can be too. Figure out what |
140 | changes would be needed to package that module and its tests up for CPAN, and |
141 | do so. Test it with older perl releases, and fix the problems you find. |
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142 | |
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143 | =head2 Improving C<threads::shared> |
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144 | |
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145 | Investigate whether C<threads::shared> could share aggregates properly with |
146 | only Perl level changes to shared.pm |
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147 | |
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148 | =head2 POSIX memory footprint |
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149 | |
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150 | Ilya observed that use POSIX; eats memory like there's no tomorrow, and at |
151 | various times worked to cut it down. There is probably still fat to cut out - |
152 | for example POSIX passes Exporter some very memory hungry data structures. |
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153 | |
eed36644 |
154 | =head2 embed.pl/makedef.pl |
155 | |
156 | There is a script F<embed.pl> that generates several header files to prefix |
157 | all of Perl's symbols in a consistent way, to provide some semblance of |
158 | namespace support in C<C>. Functions are declared in F<embed.fnc>, variables |
159 | in F<interpvar.h> and F<thrdvar.h>. Quite a few of the functions and variables |
160 | are conditionally declared there, using C<#ifdef>. However, F<embed.pl> |
161 | doesn't understand the C macros, so the rules about which symbols are present |
162 | when is duplicated in F<makedef.pl>. Writing things twice is bad, m'kay. |
163 | It would be good to teach C<embed.pl> to understand the conditional |
164 | compilation, and hence remove the duplication, and the mistakes it has caused. |
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165 | |
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166 | =head1 Tasks that need a little sysadmin-type knowledge |
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167 | |
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168 | Or if you prefer, tasks that you would learn from, and broaden your skills |
169 | base... |
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170 | |
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171 | =head2 make HTML install work |
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172 | |
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173 | There is an C<installhtml> target in the Makefile. It's marked as |
174 | "experimental". It would be good to get this tested, make it work reliably, and |
175 | remove the "experimental" tag. This would include |
176 | |
177 | =over 4 |
178 | |
179 | =item 1 |
180 | |
181 | Checking that cross linking between various parts of the documentation works. |
182 | In particular that links work between the modules (files with POD in F<lib/>) |
183 | and the core documentation (files in F<pod/>) |
184 | |
185 | =item 2 |
186 | |
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187 | Work out how to split C<perlfunc> into chunks, preferably one per function |
188 | group, preferably with general case code that could be used elsewhere. |
189 | Challenges here are correctly identifying the groups of functions that go |
190 | together, and making the right named external cross-links point to the right |
191 | page. Things to be aware of are C<-X>, groups such as C<getpwnam> to |
192 | C<endservent>, two or more C<=items> giving the different parameter lists, such |
193 | as |
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194 | |
195 | =item substr EXPR,OFFSET,LENGTH,REPLACEMENT |
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196 | =item substr EXPR,OFFSET,LENGTH |
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197 | =item substr EXPR,OFFSET |
198 | |
199 | and different parameter lists having different meanings. (eg C<select>) |
200 | |
201 | =back |
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202 | |
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203 | =head2 compressed man pages |
204 | |
205 | Be able to install them. This would probably need a configure test to see how |
206 | the system does compressed man pages (same directory/different directory? |
207 | same filename/different filename), as well as tweaking the F<installman> script |
208 | to compress as necessary. |
209 | |
30222c0f |
210 | =head2 Add a code coverage target to the Makefile |
211 | |
212 | Make it easy for anyone to run Devel::Cover on the core's tests. The steps |
213 | to do this manually are roughly |
214 | |
215 | =over 4 |
216 | |
217 | =item * |
218 | |
219 | do a normal C<Configure>, but include Devel::Cover as a module to install |
220 | (see F<INSTALL> for how to do this) |
221 | |
222 | =item * |
223 | |
224 | make perl |
225 | |
226 | =item * |
227 | |
228 | cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness |
229 | |
230 | =item * |
231 | |
232 | Process the resulting Devel::Cover database |
233 | |
234 | =back |
235 | |
236 | This just give you the coverage of the F<.pm>s. To also get the C level |
237 | coverage you need to |
238 | |
239 | =over 4 |
240 | |
241 | =item * |
242 | |
243 | Additionally tell C<Configure> to use the appropriate C compiler flags for |
244 | C<gcov> |
245 | |
246 | =item * |
247 | |
248 | make perl.gcov |
249 | |
250 | (instead of C<make perl>) |
251 | |
252 | =item * |
253 | |
254 | After running the tests run C<gcov> to generate all the F<.gcov> files. |
255 | (Including down in the subdirectories of F<ext/> |
256 | |
257 | =item * |
258 | |
259 | (From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files |
260 | to get their stats into the cover_db directory. |
261 | |
262 | =item * |
263 | |
264 | Then process the Devel::Cover database |
265 | |
266 | =back |
267 | |
268 | It would be good to add a single switch to C<Configure> to specify that you |
269 | wanted to perform perl level coverage, and another to specify C level |
270 | coverage, and have C<Configure> and the F<Makefile> do all the right things |
271 | automatically. |
272 | |
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273 | =head2 Make Config.pm cope with differences between built and installed perl |
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274 | |
275 | Quite often vendors ship a perl binary compiled with their (pay-for) |
276 | compilers. People install a free compiler, such as gcc. To work out how to |
277 | build extensions, Perl interrogates C<%Config>, so in this situation |
278 | C<%Config> describes compilers that aren't there, and extension building |
279 | fails. This forces people into choosing between re-compiling perl themselves |
280 | using the compiler they have, or only using modules that the vendor ships. |
281 | |
282 | It would be good to find a way teach C<Config.pm> about the installation setup, |
283 | possibly involving probing at install time or later, so that the C<%Config> in |
284 | a binary distribution better describes the installed machine, when the |
285 | installed machine differs from the build machine in some significant way. |
286 | |
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287 | =head2 linker specification files |
288 | |
289 | Some platforms mandate that you provide a list of a shared library's external |
290 | symbols to the linker, so the core already has the infrastructure in place to |
291 | do this for generating shared perl libraries. My understanding is that the |
292 | GNU toolchain can accept an optional linker specification file, and restrict |
293 | visibility just to symbols declared in that file. It would be good to extend |
294 | F<makedef.pl> to support this format, and to provide a means within |
295 | C<Configure> to enable it. This would allow Unix users to test that the |
296 | export list is correct, and to build a perl that does not pollute the global |
297 | namespace with private symbols. |
298 | |
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299 | =head2 Cross-compile support |
300 | |
301 | Currently C<Configure> understands C<-Dusecrosscompile> option. This option |
302 | arranges for building C<miniperl> for TARGET machine, so this C<miniperl> is |
303 | assumed then to be copied to TARGET machine and used as a replacement of full |
304 | C<perl> executable. |
305 | |
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306 | This could be done little differently. Namely C<miniperl> should be built for |
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307 | HOST and then full C<perl> with extensions should be compiled for TARGET. |
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308 | This, however, might require extra trickery for %Config: we have one config |
309 | first for HOST and then another for TARGET. |
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310 | |
311 | =head1 Tasks that need a little C knowledge |
312 | |
313 | These tasks would need a little C knowledge, but don't need any specific |
314 | background or experience with XS, or how the Perl interpreter works |
315 | |
316 | =head2 Make it clear from -v if this is the exact official release |
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317 | |
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318 | Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that |
319 | usually defines one local patch, of the form "MAINT12345" or "RC1". The output |
320 | of perl -v doesn't report that a perl isn't an official release, and this |
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321 | information can get lost in bugs reports. Because of this, the minor version |
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322 | isn't bumped up until RC time, to minimise the possibility of versions of perl |
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323 | escaping that believe themselves to be newer than they actually are. |
324 | |
325 | It would be useful to find an elegant way to have the "this is an interim |
326 | maintenance release" or "this is a release candidate" in the terse -v output, |
327 | and have it so that it's easy for the pumpking to remove this just as the |
328 | release tarball is rolled up. This way the version pulled out of rsync would |
329 | always say "I'm a development release" and it would be safe to bump the |
330 | reported minor version as soon as a release ships, which would aid perl |
331 | developers. |
332 | |
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333 | This task is really about thinking of an elegant way to arrange the C source |
334 | such that it's trivial for the Pumpking to flag "this is an official release" |
335 | when making a tarball, yet leave the default source saying "I'm not the |
336 | official release". |
337 | |
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338 | =head2 Ordering of "global" variables. |
339 | |
340 | F<thrdvar.h> and F<intrpvarh> define the "global" variables that need to be |
341 | per-thread under ithreads, where the variables are actually elements in a |
342 | structure. As C dictates, the variables must be laid out in order of |
343 | declaration. There is a comment |
344 | C</* Important ones in the first cache line (if alignment is done right) */> |
345 | which implies that at some point in the past the ordering was carefully chosen |
346 | (at least in part). However, it's clear that the ordering is less than perfect, |
347 | as currently there are things such as 7 C<bool>s in a row, then something |
348 | typically requiring 4 byte alignment, and then an odd C<bool> later on. |
349 | (C<bool>s are typically defined as C<char>s). So it would be good for someone |
350 | to review the ordering of the variables, to see how much alignment padding can |
351 | be removed. |
352 | |
d7939546 |
353 | It's also worth checking that all variables are actually used. Perl 5.8.0 |
354 | shipped with C<PL_nrs> still defined in F<thrdvar.h>, despite it being unused |
355 | since a change over a year earlier. Had this been spotted before release, it |
356 | could have been removed, but now it has to remain in the 5.8.x releases to |
357 | keep the structure the same size, to retain binary compatibility. |
358 | |
c1ab7b38 |
359 | It's probably worth checking if all need to be the types they are. For example |
360 | |
361 | PERLVAR(Ierror_count, I32) /* how many errors so far, max 10 */ |
362 | |
363 | might work as well if stored in a signed (or unsigned) 8 bit value, if the |
364 | comment is accurate. C<PL_multi_open> and C<PL_multi_close> can probably |
365 | become C<char>s. Finding variables to downsize coupled with rearrangement |
366 | could shrink the interpreter structure; a size saving which is multiplied by |
367 | the number of threads running. |
368 | |
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369 | =head2 Profile Perl - am I hot or not? |
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370 | |
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371 | The Perl source code is stable enough that it makes sense to profile it, |
372 | identify and optimise the hotspots. It would be good to measure the |
373 | performance of the Perl interpreter using free tools such as cachegrind, |
374 | gprof, and dtrace, and work to reduce the bottlenecks they reveal. |
375 | |
376 | As part of this, the idea of F<pp_hot.c> is that it contains the I<hot> ops, |
377 | the ops that are most commonly used. The idea is that by grouping them, their |
378 | object code will be adjacent in the executable, so they have a greater chance |
379 | of already being in the CPU cache (or swapped in) due to being near another op |
380 | already in use. |
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381 | |
382 | Except that it's not clear if these really are the most commonly used ops. So |
fee0a0f7 |
383 | as part of exercising your skills with coverage and profiling tools you might |
384 | want to determine what ops I<really> are the most commonly used. And in turn |
385 | suggest evictions and promotions to achieve a better F<pp_hot.c>. |
62403a3c |
386 | |
98fed0ad |
387 | =head2 Shrink struct context |
388 | |
389 | In F<cop.h>, we have |
390 | |
391 | struct context { |
392 | U32 cx_type; /* what kind of context this is */ |
393 | union { |
394 | struct block cx_blk; |
395 | struct subst cx_subst; |
396 | } cx_u; |
397 | }; |
398 | |
399 | There are less than 256 values for C<cx_type>, and the constituent parts |
400 | C<struct block> and C<struct subst> both contain some C<U8> and C<U16> fields, |
401 | so it should be possible to move them to the first word, and share space with |
402 | a C<U8> C<cx_type>, saving 1 word. |
403 | |
404 | =head2 Allocate OPs from arenas |
405 | |
406 | Currently all new OP structures are individually malloc()ed and free()d. |
407 | All C<malloc> implementations have space overheads, and are now as fast as |
408 | custom allocates so it would both use less memory and less CPU to allocate |
409 | the various OP structures from arenas. The SV arena code can probably be |
410 | re-used for this. |
411 | |
a229ae3b |
412 | =head2 Improve win32/wince.c |
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413 | |
a229ae3b |
414 | Currently, numerous functions look virtually, if not completely, |
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415 | identical in both C<win32/wince.c> and C<win32/win32.c> files, which can't |
416 | be good. |
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417 | |
0bdfc961 |
418 | =head1 Tasks that need a knowledge of XS |
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419 | |
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420 | These tasks would need C knowledge, and roughly the level of knowledge of |
421 | the perl API that comes from writing modules that use XS to interface to |
422 | C. |
423 | |
f23930d5 |
424 | =head2 shrink C<PVBM>s |
4a750395 |
425 | |
35b64ab6 |
426 | By removing unused elements and careful re-ordering, the structures for C<AV>s, |
f23930d5 |
427 | C<HV>s, C<CV>s and C<GV>s have recently been shrunk considerably. C<PVIO>s |
428 | probably aren't worth it, as typical programs don't use more than 8, and |
429 | (at least) C<Filter::Util::Call> uses C<SvPVX>/C<SvCUR>/C<SvLEN> on a C<PVIO>, |
430 | so it would mean code changes to modules on CPAN. C<PVBM>s might have some |
431 | savings to win. |
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432 | |
cd793d32 |
433 | =head2 autovivification |
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434 | |
cd793d32 |
435 | Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict; |
e50bb9a1 |
436 | |
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437 | This task is incremental - even a little bit of work on it will help. |
e50bb9a1 |
438 | |
0bdfc961 |
439 | =head2 Unicode in Filenames |
e50bb9a1 |
440 | |
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441 | chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open, |
442 | opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen, |
443 | system, truncate, unlink, utime, -X. All these could potentially accept |
444 | Unicode filenames either as input or output (and in the case of system |
445 | and qx Unicode in general, as input or output to/from the shell). |
446 | Whether a filesystem - an operating system pair understands Unicode in |
447 | filenames varies. |
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448 | |
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449 | Known combinations that have some level of understanding include |
450 | Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac |
451 | OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to |
452 | create Unicode filenames, what forms of Unicode are accepted and used |
453 | (UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used, |
454 | and so on, varies. Finding the right level of interfacing to Perl |
455 | requires some thought. Remember that an OS does not implicate a |
456 | filesystem. |
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457 | |
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458 | (The Windows -C command flag "wide API support" has been at least |
459 | temporarily retired in 5.8.1, and the -C has been repurposed, see |
460 | L<perlrun>.) |
969e704b |
461 | |
0bdfc961 |
462 | =head2 Unicode in %ENV |
969e704b |
463 | |
0bdfc961 |
464 | Currently the %ENV entries are always byte strings. |
e50bb9a1 |
465 | |
0bdfc961 |
466 | =head2 use less 'memory' |
e50bb9a1 |
467 | |
0bdfc961 |
468 | Investigate trade offs to switch out perl's choices on memory usage. |
469 | Particularly perl should be able to give memory back. |
e50bb9a1 |
470 | |
0bdfc961 |
471 | This task is incremental - even a little bit of work on it will help. |
0abe3f7c |
472 | |
0bdfc961 |
473 | =head2 Re-implement C<:unique> in a way that is actually thread-safe |
0abe3f7c |
474 | |
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475 | The old implementation made bad assumptions on several levels. A good 90% |
476 | solution might be just to make C<:unique> work to share the string buffer |
477 | of SvPVs. That way large constant strings can be shared between ithreads, |
478 | such as the configuration information in F<Config>. |
0abe3f7c |
479 | |
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480 | =head2 Make tainting consistent |
0abe3f7c |
481 | |
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482 | Tainting would be easier to use if it didn't take documented shortcuts and |
483 | allow taint to "leak" everywhere within an expression. |
0abe3f7c |
484 | |
0bdfc961 |
485 | =head2 readpipe(LIST) |
0abe3f7c |
486 | |
0bdfc961 |
487 | system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid |
488 | running a shell. readpipe() (the function behind qx//) could be similarly |
489 | extended. |
0abe3f7c |
490 | |
d1307786 |
491 | =head2 strcat(), strcpy(), strncat(), strncpy(), sprintf(), vsprintf() |
e50bb9a1 |
492 | |
d1307786 |
493 | Maybe create a utility that checks after each libperl.a creation that |
494 | none of the above (nor sprintf(), vsprintf(), or *SHUDDER* gets()) |
495 | ever creep back to libperl.a. |
e50bb9a1 |
496 | |
d1307786 |
497 | nm libperl.a | ./miniperl -alne '$o = $F[0] if /:$/; print "$o $F[1]" if $F[0] eq "U" && $F[1] =~ /^(?:strn?c(?:at|py)|v?sprintf|gets)$/' |
e50bb9a1 |
498 | |
d1307786 |
499 | Note, of course, that this will only tell whether B<your> platform |
500 | is using those naughty interfaces. |
f86a8bc5 |
501 | |
0bdfc961 |
502 | =head1 Tasks that need a knowledge of the interpreter |
3298bd4d |
503 | |
0bdfc961 |
504 | These tasks would need C knowledge, and knowledge of how the interpreter works, |
505 | or a willingness to learn. |
3298bd4d |
506 | |
d10fc472 |
507 | =head2 Attach/detach debugger from running program |
1626a787 |
508 | |
cd793d32 |
509 | The old perltodo notes "With C<gdb>, you can attach the debugger to a running |
510 | program if you pass the process ID. It would be good to do this with the Perl |
0bdfc961 |
511 | debugger on a running Perl program, although I'm not sure how it would be |
512 | done." ssh and screen do this with named pipes in /tmp. Maybe we can too. |
1626a787 |
513 | |
0bdfc961 |
514 | =head2 LVALUE functions for lists |
515 | |
516 | The old perltodo notes that lvalue functions don't work for list or hash |
517 | slices. This would be good to fix. |
518 | |
519 | =head2 LVALUE functions in the debugger |
520 | |
521 | The old perltodo notes that lvalue functions don't work in the debugger. This |
522 | would be good to fix. |
523 | |
524 | =head2 _ prototype character |
525 | |
526 | Study the possibility of adding a new prototype character, C<_>, meaning |
527 | "this argument defaults to $_". |
528 | |
0bdfc961 |
529 | =head2 regexp optimiser optional |
530 | |
531 | The regexp optimiser is not optional. It should configurable to be, to allow |
532 | its performance to be measured, and its bugs to be easily demonstrated. |
533 | |
534 | =head2 UNITCHECK |
535 | |
536 | Introduce a new special block, UNITCHECK, which is run at the end of a |
537 | compilation unit (module, file, eval(STRING) block). This will correspond to |
538 | the Perl 6 CHECK. Perl 5's CHECK cannot be changed or removed because the |
539 | O.pm/B.pm backend framework depends on it. |
540 | |
02f21748 |
541 | =head2 delete &function |
542 | |
543 | Allow to delete functions. One can already undef them, but they're still |
544 | in the stash. |
545 | |
546 | =head2 Make readpipe overridable |
547 | |
548 | so we can override qx// as well. |
549 | |
0bdfc961 |
550 | =head2 optional optimizer |
551 | |
552 | Make the peephole optimizer optional. Currently it performs two tasks as |
553 | it walks the optree - genuine peephole optimisations, and necessary fixups of |
554 | ops. It would be good to find an efficient way to switch out the |
555 | optimisations whilst keeping the fixups. |
556 | |
557 | =head2 You WANT *how* many |
558 | |
559 | Currently contexts are void, scalar and list. split has a special mechanism in |
560 | place to pass in the number of return values wanted. It would be useful to |
561 | have a general mechanism for this, backwards compatible and little speed hit. |
562 | This would allow proposals such as short circuiting sort to be implemented |
563 | as a module on CPAN. |
564 | |
565 | =head2 lexical aliases |
566 | |
567 | Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>. |
568 | |
569 | =head2 entersub XS vs Perl |
570 | |
571 | At the moment pp_entersub is huge, and has code to deal with entering both |
572 | perl and XS subroutines. Subroutine implementations rarely change between |
573 | perl and XS at run time, so investigate using 2 ops to enter subs (one for |
574 | XS, one for perl) and swap between if a sub is redefined. |
2810d901 |
575 | |
576 | =head2 Self ties |
577 | |
578 | self ties are currently illegal because they caused too many segfaults. Maybe |
579 | the causes of these could be tracked down and self-ties on all types re- |
580 | instated. |
0bdfc961 |
581 | |
582 | =head2 Optimize away @_ |
583 | |
584 | The old perltodo notes "Look at the "reification" code in C<av.c>". |
585 | |
0bdfc961 |
586 | =head2 What hooks would assertions need? |
587 | |
588 | Assertions are in the core, and work. However, assertions needed to be added |
589 | as a core patch, rather than an XS module in ext, or a CPAN module, because |
590 | the core has no hooks in the necessary places. It would be useful to |
591 | investigate what hooks would need to be added to make it possible to provide |
592 | the full assertion support from a CPAN module, so that we aren't constraining |
593 | the imagination of future CPAN authors. |
594 | |
16fc99ce |
595 | =head2 Properly Unicode safe tokeniser and pads. |
596 | |
597 | The tokeniser isn't actually very UTF-8 clean. C<use utf8;> is a hack - |
598 | variable names are stored in stashes as raw bytes, without the utf-8 flag |
599 | set. The pad API only takes a C<char *> pointer, so that's all bytes too. The |
600 | tokeniser ignores the UTF-8-ness of C<PL_rsfp>, or any SVs returned from |
601 | source filters. All this could be fixed. |
602 | |
0bdfc961 |
603 | =head1 Big projects |
604 | |
605 | Tasks that will get your name mentioned in the description of the "Highlights |
606 | of 5.10" |
607 | |
608 | =head2 make ithreads more robust |
609 | |
4e577f8b |
610 | Generally make ithreads more robust. See also L</iCOW> |
0bdfc961 |
611 | |
612 | This task is incremental - even a little bit of work on it will help, and |
613 | will be greatly appreciated. |
614 | |
6c047da7 |
615 | One bit would be to write the missing code in sv.c:Perl_dirp_dup. |
616 | |
0bdfc961 |
617 | =head2 iCOW |
618 | |
619 | Sarathy and Arthur have a proposal for an improved Copy On Write which |
620 | specifically will be able to COW new ithreads. If this can be implemented |
621 | it would be a good thing. |
622 | |
623 | =head2 (?{...}) closures in regexps |
624 | |
625 | Fix (or rewrite) the implementation of the C</(?{...})/> closures. |
626 | |
627 | =head2 A re-entrant regexp engine |
628 | |
629 | This will allow the use of a regex from inside (?{ }), (??{ }) and |
630 | (?(?{ })|) constructs. |