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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 Tasks that only need Perl knowledge |
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24 | |
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25 | =head2 common test code for timed bail out |
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26 | |
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27 | Write portable self destruct code for tests to stop them burning CPU in |
28 | infinite loops. This needs to avoid using alarm, as some of the tests are |
29 | testing alarm/sleep or timers. |
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30 | |
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31 | =head2 POD -E<gt> HTML conversion in the core still sucks |
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32 | |
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33 | Which is crazy given just how simple POD purports to be, and how simple HTML |
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34 | can be. It's not actually I<as> simple as it sounds, particularly with the |
35 | flexibility POD allows for C<=item>, but it would be good to improve the |
36 | visual appeal of the HTML generated, and to avoid it having any validation |
37 | errors. See also L</make HTML install work>, as the layout of installation tree |
38 | is needed to improve the cross-linking. |
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39 | |
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40 | The addition of C<Pod::Simple> and its related modules may make this task |
41 | easier to complete. |
42 | |
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43 | =head2 Parallel testing |
44 | |
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45 | (This probably impacts much more than the core: also the Test::Harness |
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46 | and TAP::* modules on CPAN.) |
47 | |
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48 | The core regression test suite is getting ever more comprehensive, which has |
49 | the side effect that it takes longer to run. This isn't so good. Investigate |
50 | whether it would be feasible to give the harness script the B<option> of |
51 | running sets of tests in parallel. This would be useful for tests in |
52 | F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>. |
53 | |
54 | Questions to answer |
55 | |
56 | =over 4 |
57 | |
58 | =item 1 |
59 | |
60 | How does screen layout work when you're running more than one test? |
61 | |
62 | =item 2 |
63 | |
64 | How does the caller of test specify how many tests to run in parallel? |
65 | |
66 | =item 3 |
67 | |
68 | How do setup/teardown tests identify themselves? |
69 | |
70 | =back |
71 | |
72 | Pugs already does parallel testing - can their approach be re-used? |
73 | |
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74 | =head2 Make Schwern poorer |
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75 | |
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76 | We should have tests for everything. When all the core's modules are tested, |
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77 | Schwern has promised to donate to $500 to TPF. We may need volunteers to |
78 | hold him upside down and shake vigorously in order to actually extract the |
79 | cash. |
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80 | |
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81 | =head2 Improve the coverage of the core tests |
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82 | |
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83 | Use Devel::Cover to ascertain the core modules's test coverage, then add |
84 | tests that are currently missing. |
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85 | |
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86 | =head2 test B |
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87 | |
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88 | A full test suite for the B module would be nice. |
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89 | |
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90 | =head2 Deparse inlined constants |
91 | |
92 | Code such as this |
93 | |
94 | use constant PI => 4; |
95 | warn PI |
96 | |
97 | will currently deparse as |
98 | |
99 | use constant ('PI', 4); |
100 | warn 4; |
101 | |
102 | because the tokenizer inlines the value of the constant subroutine C<PI>. |
103 | This allows various compile time optimisations, such as constant folding |
104 | and dead code elimination. Where these haven't happened (such as the example |
105 | above) it ought be possible to make B::Deparse work out the name of the |
106 | original constant, because just enough information survives in the symbol |
107 | table to do this. Specifically, the same scalar is used for the constant in |
108 | the optree as is used for the constant subroutine, so by iterating over all |
109 | symbol tables and generating a mapping of SV address to constant name, it |
110 | would be possible to provide B::Deparse with this functionality. |
111 | |
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112 | =head2 A decent benchmark |
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113 | |
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114 | C<perlbench> seems impervious to any recent changes made to the perl core. It |
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115 | would be useful to have a reasonable general benchmarking suite that roughly |
116 | represented what current perl programs do, and measurably reported whether |
117 | tweaks to the core improve, degrade or don't really affect performance, to |
118 | guide people attempting to optimise the guts of perl. Gisle would welcome |
119 | new tests for perlbench. |
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120 | |
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121 | =head2 fix tainting bugs |
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122 | |
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123 | Fix the bugs revealed by running the test suite with the C<-t> switch (via |
124 | C<make test.taintwarn>). |
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125 | |
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126 | =head2 Dual life everything |
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127 | |
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128 | As part of the "dists" plan, anything that doesn't belong in the smallest perl |
129 | distribution needs to be dual lifed. Anything else can be too. Figure out what |
130 | changes would be needed to package that module and its tests up for CPAN, and |
131 | do so. Test it with older perl releases, and fix the problems you find. |
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132 | |
a393eb28 |
133 | To make a minimal perl distribution, it's useful to look at |
134 | F<t/lib/commonsense.t>. |
135 | |
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136 | =head2 Improving C<threads::shared> |
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137 | |
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138 | Investigate whether C<threads::shared> could share aggregates properly with |
139 | only Perl level changes to shared.pm |
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140 | |
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141 | =head2 POSIX memory footprint |
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142 | |
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143 | Ilya observed that use POSIX; eats memory like there's no tomorrow, and at |
144 | various times worked to cut it down. There is probably still fat to cut out - |
145 | for example POSIX passes Exporter some very memory hungry data structures. |
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146 | |
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147 | =head2 embed.pl/makedef.pl |
148 | |
149 | There is a script F<embed.pl> that generates several header files to prefix |
150 | all of Perl's symbols in a consistent way, to provide some semblance of |
151 | namespace support in C<C>. Functions are declared in F<embed.fnc>, variables |
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152 | in F<interpvar.h>. Quite a few of the functions and variables |
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153 | are conditionally declared there, using C<#ifdef>. However, F<embed.pl> |
154 | doesn't understand the C macros, so the rules about which symbols are present |
155 | when is duplicated in F<makedef.pl>. Writing things twice is bad, m'kay. |
156 | It would be good to teach C<embed.pl> to understand the conditional |
157 | compilation, and hence remove the duplication, and the mistakes it has caused. |
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158 | |
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159 | =head2 use strict; and AutoLoad |
160 | |
161 | Currently if you write |
162 | |
163 | package Whack; |
164 | use AutoLoader 'AUTOLOAD'; |
165 | use strict; |
166 | 1; |
167 | __END__ |
168 | sub bloop { |
169 | print join (' ', No, strict, here), "!\n"; |
170 | } |
171 | |
172 | then C<use strict;> isn't in force within the autoloaded subroutines. It would |
173 | be more consistent (and less surprising) to arrange for all lexical pragmas |
174 | in force at the __END__ block to be in force within each autoloaded subroutine. |
175 | |
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176 | There's a similar problem with SelfLoader. |
177 | |
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178 | =head1 Tasks that need a little sysadmin-type knowledge |
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179 | |
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180 | Or if you prefer, tasks that you would learn from, and broaden your skills |
181 | base... |
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182 | |
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183 | =head2 make HTML install work |
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184 | |
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185 | There is an C<installhtml> target in the Makefile. It's marked as |
186 | "experimental". It would be good to get this tested, make it work reliably, and |
187 | remove the "experimental" tag. This would include |
188 | |
189 | =over 4 |
190 | |
191 | =item 1 |
192 | |
193 | Checking that cross linking between various parts of the documentation works. |
194 | In particular that links work between the modules (files with POD in F<lib/>) |
195 | and the core documentation (files in F<pod/>) |
196 | |
197 | =item 2 |
198 | |
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199 | Work out how to split C<perlfunc> into chunks, preferably one per function |
200 | group, preferably with general case code that could be used elsewhere. |
201 | Challenges here are correctly identifying the groups of functions that go |
202 | together, and making the right named external cross-links point to the right |
203 | page. Things to be aware of are C<-X>, groups such as C<getpwnam> to |
204 | C<endservent>, two or more C<=items> giving the different parameter lists, such |
205 | as |
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206 | |
207 | =item substr EXPR,OFFSET,LENGTH,REPLACEMENT |
adebf063 |
208 | =item substr EXPR,OFFSET,LENGTH |
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209 | =item substr EXPR,OFFSET |
210 | |
211 | and different parameter lists having different meanings. (eg C<select>) |
212 | |
213 | =back |
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214 | |
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215 | =head2 compressed man pages |
216 | |
217 | Be able to install them. This would probably need a configure test to see how |
218 | the system does compressed man pages (same directory/different directory? |
219 | same filename/different filename), as well as tweaking the F<installman> script |
220 | to compress as necessary. |
221 | |
30222c0f |
222 | =head2 Add a code coverage target to the Makefile |
223 | |
224 | Make it easy for anyone to run Devel::Cover on the core's tests. The steps |
225 | to do this manually are roughly |
226 | |
227 | =over 4 |
228 | |
229 | =item * |
230 | |
231 | do a normal C<Configure>, but include Devel::Cover as a module to install |
232 | (see F<INSTALL> for how to do this) |
233 | |
234 | =item * |
235 | |
236 | make perl |
237 | |
238 | =item * |
239 | |
240 | cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness |
241 | |
242 | =item * |
243 | |
244 | Process the resulting Devel::Cover database |
245 | |
246 | =back |
247 | |
248 | This just give you the coverage of the F<.pm>s. To also get the C level |
249 | coverage you need to |
250 | |
251 | =over 4 |
252 | |
253 | =item * |
254 | |
255 | Additionally tell C<Configure> to use the appropriate C compiler flags for |
256 | C<gcov> |
257 | |
258 | =item * |
259 | |
260 | make perl.gcov |
261 | |
262 | (instead of C<make perl>) |
263 | |
264 | =item * |
265 | |
266 | After running the tests run C<gcov> to generate all the F<.gcov> files. |
267 | (Including down in the subdirectories of F<ext/> |
268 | |
269 | =item * |
270 | |
271 | (From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files |
272 | to get their stats into the cover_db directory. |
273 | |
274 | =item * |
275 | |
276 | Then process the Devel::Cover database |
277 | |
278 | =back |
279 | |
280 | It would be good to add a single switch to C<Configure> to specify that you |
281 | wanted to perform perl level coverage, and another to specify C level |
282 | coverage, and have C<Configure> and the F<Makefile> do all the right things |
283 | automatically. |
284 | |
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285 | =head2 Make Config.pm cope with differences between built and installed perl |
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286 | |
287 | Quite often vendors ship a perl binary compiled with their (pay-for) |
288 | compilers. People install a free compiler, such as gcc. To work out how to |
289 | build extensions, Perl interrogates C<%Config>, so in this situation |
290 | C<%Config> describes compilers that aren't there, and extension building |
291 | fails. This forces people into choosing between re-compiling perl themselves |
292 | using the compiler they have, or only using modules that the vendor ships. |
293 | |
294 | It would be good to find a way teach C<Config.pm> about the installation setup, |
295 | possibly involving probing at install time or later, so that the C<%Config> in |
296 | a binary distribution better describes the installed machine, when the |
297 | installed machine differs from the build machine in some significant way. |
298 | |
728f4ecd |
299 | =head2 linker specification files |
300 | |
301 | Some platforms mandate that you provide a list of a shared library's external |
302 | symbols to the linker, so the core already has the infrastructure in place to |
303 | do this for generating shared perl libraries. My understanding is that the |
304 | GNU toolchain can accept an optional linker specification file, and restrict |
305 | visibility just to symbols declared in that file. It would be good to extend |
306 | F<makedef.pl> to support this format, and to provide a means within |
307 | C<Configure> to enable it. This would allow Unix users to test that the |
308 | export list is correct, and to build a perl that does not pollute the global |
309 | namespace with private symbols. |
310 | |
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311 | =head2 Cross-compile support |
312 | |
313 | Currently C<Configure> understands C<-Dusecrosscompile> option. This option |
314 | arranges for building C<miniperl> for TARGET machine, so this C<miniperl> is |
315 | assumed then to be copied to TARGET machine and used as a replacement of full |
316 | C<perl> executable. |
317 | |
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318 | This could be done little differently. Namely C<miniperl> should be built for |
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319 | HOST and then full C<perl> with extensions should be compiled for TARGET. |
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320 | This, however, might require extra trickery for %Config: we have one config |
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321 | first for HOST and then another for TARGET. Tools like MakeMaker will be |
322 | mightily confused. Having around two different types of executables and |
323 | libraries (HOST and TARGET) makes life interesting for Makefiles and |
324 | shell (and Perl) scripts. There is $Config{run}, normally empty, which |
325 | can be used as an execution wrapper. Also note that in some |
326 | cross-compilation/execution environments the HOST and the TARGET do |
327 | not see the same filesystem(s), the $Config{run} may need to do some |
328 | file/directory copying back and forth. |
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329 | |
330 | =head1 Tasks that need a little C knowledge |
331 | |
332 | These tasks would need a little C knowledge, but don't need any specific |
333 | background or experience with XS, or how the Perl interpreter works |
334 | |
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335 | =head2 Modernize the order of directories in @INC |
336 | |
337 | The way @INC is laid out by default, one cannot upgrade core (dual-life) |
338 | modules without overwriting files. This causes problems for binary |
339 | package builders. |
340 | |
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341 | =head2 Make it clear from -v if this is the exact official release |
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342 | |
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343 | Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that |
344 | usually defines one local patch, of the form "MAINT12345" or "RC1". The output |
345 | of perl -v doesn't report that a perl isn't an official release, and this |
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346 | information can get lost in bugs reports. Because of this, the minor version |
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347 | isn't bumped up until RC time, to minimise the possibility of versions of perl |
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348 | escaping that believe themselves to be newer than they actually are. |
349 | |
350 | It would be useful to find an elegant way to have the "this is an interim |
351 | maintenance release" or "this is a release candidate" in the terse -v output, |
352 | and have it so that it's easy for the pumpking to remove this just as the |
353 | release tarball is rolled up. This way the version pulled out of rsync would |
354 | always say "I'm a development release" and it would be safe to bump the |
355 | reported minor version as soon as a release ships, which would aid perl |
356 | developers. |
357 | |
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358 | This task is really about thinking of an elegant way to arrange the C source |
359 | such that it's trivial for the Pumpking to flag "this is an official release" |
360 | when making a tarball, yet leave the default source saying "I'm not the |
361 | official release". |
362 | |
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363 | =head2 Profile Perl - am I hot or not? |
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364 | |
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365 | The Perl source code is stable enough that it makes sense to profile it, |
366 | identify and optimise the hotspots. It would be good to measure the |
367 | performance of the Perl interpreter using free tools such as cachegrind, |
368 | gprof, and dtrace, and work to reduce the bottlenecks they reveal. |
369 | |
370 | As part of this, the idea of F<pp_hot.c> is that it contains the I<hot> ops, |
371 | the ops that are most commonly used. The idea is that by grouping them, their |
372 | object code will be adjacent in the executable, so they have a greater chance |
373 | of already being in the CPU cache (or swapped in) due to being near another op |
374 | already in use. |
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375 | |
376 | Except that it's not clear if these really are the most commonly used ops. So |
fee0a0f7 |
377 | as part of exercising your skills with coverage and profiling tools you might |
378 | want to determine what ops I<really> are the most commonly used. And in turn |
379 | suggest evictions and promotions to achieve a better F<pp_hot.c>. |
62403a3c |
380 | |
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381 | =head2 Allocate OPs from arenas |
382 | |
383 | Currently all new OP structures are individually malloc()ed and free()d. |
384 | All C<malloc> implementations have space overheads, and are now as fast as |
385 | custom allocates so it would both use less memory and less CPU to allocate |
386 | the various OP structures from arenas. The SV arena code can probably be |
387 | re-used for this. |
388 | |
539f2c54 |
389 | Note that Configuring perl with C<-Accflags=-DPL_OP_SLAB_ALLOC> will use |
390 | Perl_Slab_alloc() to pack optrees into a contiguous block, which is |
391 | probably superior to the use of OP arenas, esp. from a cache locality |
392 | standpoint. See L<Profile Perl - am I hot or not?>. |
393 | |
a229ae3b |
394 | =head2 Improve win32/wince.c |
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395 | |
a229ae3b |
396 | Currently, numerous functions look virtually, if not completely, |
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397 | identical in both C<win32/wince.c> and C<win32/win32.c> files, which can't |
6d71adcd |
398 | be good. |
399 | |
c5b31784 |
400 | =head2 Use secure CRT functions when building with VC8 on Win32 |
401 | |
402 | Visual C++ 2005 (VC++ 8.x) deprecated a number of CRT functions on the basis |
403 | that they were "unsafe" and introduced differently named secure versions of |
404 | them as replacements, e.g. instead of writing |
405 | |
406 | FILE* f = fopen(__FILE__, "r"); |
407 | |
408 | one should now write |
409 | |
410 | FILE* f; |
411 | errno_t err = fopen_s(&f, __FILE__, "r"); |
412 | |
413 | Currently, the warnings about these deprecations have been disabled by adding |
414 | -D_CRT_SECURE_NO_DEPRECATE to the CFLAGS. It would be nice to remove that |
415 | warning suppressant and actually make use of the new secure CRT functions. |
416 | |
417 | There is also a similar issue with POSIX CRT function names like fileno having |
418 | been deprecated in favour of ISO C++ conformant names like _fileno. These |
26a6faa8 |
419 | warnings are also currently suppressed by adding -D_CRT_NONSTDC_NO_DEPRECATE. It |
c5b31784 |
420 | might be nice to do as Microsoft suggest here too, although, unlike the secure |
421 | functions issue, there is presumably little or no benefit in this case. |
422 | |
6d71adcd |
423 | =head1 Tasks that need a knowledge of XS |
424 | |
425 | These tasks would need C knowledge, and roughly the level of knowledge of |
426 | the perl API that comes from writing modules that use XS to interface to |
427 | C. |
428 | |
6d71adcd |
429 | =head2 autovivification |
430 | |
431 | Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict; |
432 | |
433 | This task is incremental - even a little bit of work on it will help. |
434 | |
435 | =head2 Unicode in Filenames |
436 | |
437 | chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open, |
438 | opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen, |
439 | system, truncate, unlink, utime, -X. All these could potentially accept |
440 | Unicode filenames either as input or output (and in the case of system |
441 | and qx Unicode in general, as input or output to/from the shell). |
442 | Whether a filesystem - an operating system pair understands Unicode in |
443 | filenames varies. |
444 | |
445 | Known combinations that have some level of understanding include |
446 | Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac |
447 | OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to |
448 | create Unicode filenames, what forms of Unicode are accepted and used |
449 | (UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used, |
450 | and so on, varies. Finding the right level of interfacing to Perl |
451 | requires some thought. Remember that an OS does not implicate a |
452 | filesystem. |
453 | |
454 | (The Windows -C command flag "wide API support" has been at least |
455 | temporarily retired in 5.8.1, and the -C has been repurposed, see |
456 | L<perlrun>.) |
457 | |
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458 | Most probably the right way to do this would be this: |
459 | L</"Virtualize operating system access">. |
460 | |
6d71adcd |
461 | =head2 Unicode in %ENV |
462 | |
463 | Currently the %ENV entries are always byte strings. |
87a942b1 |
464 | See L</"Virtualize operating system access">. |
6d71adcd |
465 | |
1f2e7916 |
466 | =head2 Unicode and glob() |
467 | |
468 | Currently glob patterns and filenames returned from File::Glob::glob() |
87a942b1 |
469 | are always byte strings. See L</"Virtualize operating system access">. |
1f2e7916 |
470 | |
dbb0c492 |
471 | =head2 Unicode and lc/uc operators |
472 | |
473 | Some built-in operators (C<lc>, C<uc>, etc.) behave differently, based on |
474 | what the internal encoding of their argument is. That should not be the |
475 | case. Maybe add a pragma to switch behaviour. |
476 | |
6d71adcd |
477 | =head2 use less 'memory' |
478 | |
479 | Investigate trade offs to switch out perl's choices on memory usage. |
480 | Particularly perl should be able to give memory back. |
481 | |
482 | This task is incremental - even a little bit of work on it will help. |
483 | |
484 | =head2 Re-implement C<:unique> in a way that is actually thread-safe |
485 | |
486 | The old implementation made bad assumptions on several levels. A good 90% |
487 | solution might be just to make C<:unique> work to share the string buffer |
488 | of SvPVs. That way large constant strings can be shared between ithreads, |
489 | such as the configuration information in F<Config>. |
490 | |
491 | =head2 Make tainting consistent |
492 | |
493 | Tainting would be easier to use if it didn't take documented shortcuts and |
494 | allow taint to "leak" everywhere within an expression. |
495 | |
496 | =head2 readpipe(LIST) |
497 | |
498 | system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid |
499 | running a shell. readpipe() (the function behind qx//) could be similarly |
500 | extended. |
501 | |
502 | =head2 strcat(), strcpy(), strncat(), strncpy(), sprintf(), vsprintf() |
503 | |
504 | Maybe create a utility that checks after each libperl.a creation that |
505 | none of the above (nor sprintf(), vsprintf(), or *SHUDDER* gets()) |
506 | ever creep back to libperl.a. |
507 | |
508 | nm libperl.a | ./miniperl -alne '$o = $F[0] if /:$/; print "$o $F[1]" if $F[0] eq "U" && $F[1] =~ /^(?:strn?c(?:at|py)|v?sprintf|gets)$/' |
509 | |
510 | Note, of course, that this will only tell whether B<your> platform |
511 | is using those naughty interfaces. |
512 | |
513 | =head2 Audit the code for destruction ordering assumptions |
514 | |
515 | Change 25773 notes |
516 | |
517 | /* Need to check SvMAGICAL, as during global destruction it may be that |
518 | AvARYLEN(av) has been freed before av, and hence the SvANY() pointer |
519 | is now part of the linked list of SV heads, rather than pointing to |
520 | the original body. */ |
521 | /* FIXME - audit the code for other bugs like this one. */ |
522 | |
523 | adding the C<SvMAGICAL> check to |
524 | |
525 | if (AvARYLEN(av) && SvMAGICAL(AvARYLEN(av))) { |
526 | MAGIC *mg = mg_find (AvARYLEN(av), PERL_MAGIC_arylen); |
527 | |
528 | Go through the core and look for similar assumptions that SVs have particular |
529 | types, as all bets are off during global destruction. |
530 | |
749904bf |
531 | =head2 Extend PerlIO and PerlIO::Scalar |
532 | |
533 | PerlIO::Scalar doesn't know how to truncate(). Implementing this |
534 | would require extending the PerlIO vtable. |
535 | |
536 | Similarly the PerlIO vtable doesn't know about formats (write()), or |
537 | about stat(), or chmod()/chown(), utime(), or flock(). |
538 | |
539 | (For PerlIO::Scalar it's hard to see what e.g. mode bits or ownership |
540 | would mean.) |
541 | |
542 | PerlIO doesn't do directories or symlinks, either: mkdir(), rmdir(), |
543 | opendir(), closedir(), seekdir(), rewinddir(), glob(); symlink(), |
544 | readlink(). |
545 | |
94da6c29 |
546 | See also L</"Virtualize operating system access">. |
547 | |
3236f110 |
548 | =head2 -C on the #! line |
549 | |
550 | It should be possible to make -C work correctly if found on the #! line, |
551 | given that all perl command line options are strict ASCII, and -C changes |
552 | only the interpretation of non-ASCII characters, and not for the script file |
553 | handle. To make it work needs some investigation of the ordering of function |
554 | calls during startup, and (by implication) a bit of tweaking of that order. |
555 | |
556 | |
0bdfc961 |
557 | =head1 Tasks that need a knowledge of the interpreter |
3298bd4d |
558 | |
0bdfc961 |
559 | These tasks would need C knowledge, and knowledge of how the interpreter works, |
560 | or a willingness to learn. |
3298bd4d |
561 | |
636e63cb |
562 | =head2 state variable initialization in list context |
563 | |
564 | Currently this is illegal: |
565 | |
566 | state ($a, $b) = foo(); |
567 | |
568 | The current Perl 6 design is that C<state ($a) = foo();> and |
569 | C<(state $a) = foo();> have different semantics, which is tricky to implement |
570 | in Perl 5 as currently the produce the same opcode trees. It would be useful |
571 | to clarify that the Perl 6 design is firm, and then implement the necessary |
572 | code in Perl 5. There are comments in C<Perl_newASSIGNOP()> that show the |
573 | code paths taken by various assignment constructions involving state variables. |
574 | |
4fedb12c |
575 | =head2 Implement $value ~~ 0 .. $range |
576 | |
577 | It would be nice to extend the syntax of the C<~~> operator to also |
578 | understand numeric (and maybe alphanumeric) ranges. |
a393eb28 |
579 | |
580 | =head2 A does() built-in |
581 | |
582 | Like ref(), only useful. It would call the C<DOES> method on objects; it |
583 | would also tell whether something can be dereferenced as an |
584 | array/hash/etc., or used as a regexp, etc. |
585 | L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-03/msg00481.html> |
586 | |
587 | =head2 Tied filehandles and write() don't mix |
588 | |
589 | There is no method on tied filehandles to allow them to be called back by |
590 | formats. |
4fedb12c |
591 | |
d10fc472 |
592 | =head2 Attach/detach debugger from running program |
1626a787 |
593 | |
cd793d32 |
594 | The old perltodo notes "With C<gdb>, you can attach the debugger to a running |
595 | program if you pass the process ID. It would be good to do this with the Perl |
0bdfc961 |
596 | debugger on a running Perl program, although I'm not sure how it would be |
597 | done." ssh and screen do this with named pipes in /tmp. Maybe we can too. |
1626a787 |
598 | |
a8cb5b9e |
599 | =head2 Optimize away empty destructors |
600 | |
601 | Defining an empty DESTROY method might be useful (notably in |
602 | AUTOLOAD-enabled classes), but it's still a bit expensive to call. That |
603 | could probably be optimized. |
604 | |
0bdfc961 |
605 | =head2 LVALUE functions for lists |
606 | |
607 | The old perltodo notes that lvalue functions don't work for list or hash |
608 | slices. This would be good to fix. |
609 | |
610 | =head2 LVALUE functions in the debugger |
611 | |
612 | The old perltodo notes that lvalue functions don't work in the debugger. This |
613 | would be good to fix. |
614 | |
0bdfc961 |
615 | =head2 regexp optimiser optional |
616 | |
617 | The regexp optimiser is not optional. It should configurable to be, to allow |
618 | its performance to be measured, and its bugs to be easily demonstrated. |
619 | |
02f21748 |
620 | =head2 delete &function |
621 | |
622 | Allow to delete functions. One can already undef them, but they're still |
623 | in the stash. |
624 | |
ef36c6a7 |
625 | =head2 C</w> regex modifier |
626 | |
627 | That flag would enable to match whole words, and also to interpolate |
628 | arrays as alternations. With it, C</P/w> would be roughly equivalent to: |
629 | |
630 | do { local $"='|'; /\b(?:P)\b/ } |
631 | |
632 | See L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-01/msg00400.html> |
633 | for the discussion. |
634 | |
0bdfc961 |
635 | =head2 optional optimizer |
636 | |
637 | Make the peephole optimizer optional. Currently it performs two tasks as |
638 | it walks the optree - genuine peephole optimisations, and necessary fixups of |
639 | ops. It would be good to find an efficient way to switch out the |
640 | optimisations whilst keeping the fixups. |
641 | |
642 | =head2 You WANT *how* many |
643 | |
644 | Currently contexts are void, scalar and list. split has a special mechanism in |
645 | place to pass in the number of return values wanted. It would be useful to |
646 | have a general mechanism for this, backwards compatible and little speed hit. |
647 | This would allow proposals such as short circuiting sort to be implemented |
648 | as a module on CPAN. |
649 | |
650 | =head2 lexical aliases |
651 | |
652 | Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>. |
653 | |
654 | =head2 entersub XS vs Perl |
655 | |
656 | At the moment pp_entersub is huge, and has code to deal with entering both |
657 | perl and XS subroutines. Subroutine implementations rarely change between |
658 | perl and XS at run time, so investigate using 2 ops to enter subs (one for |
659 | XS, one for perl) and swap between if a sub is redefined. |
2810d901 |
660 | |
661 | =head2 Self ties |
662 | |
663 | self ties are currently illegal because they caused too many segfaults. Maybe |
664 | the causes of these could be tracked down and self-ties on all types re- |
665 | instated. |
0bdfc961 |
666 | |
667 | =head2 Optimize away @_ |
668 | |
669 | The old perltodo notes "Look at the "reification" code in C<av.c>". |
670 | |
16fc99ce |
671 | =head2 Properly Unicode safe tokeniser and pads. |
672 | |
673 | The tokeniser isn't actually very UTF-8 clean. C<use utf8;> is a hack - |
674 | variable names are stored in stashes as raw bytes, without the utf-8 flag |
675 | set. The pad API only takes a C<char *> pointer, so that's all bytes too. The |
676 | tokeniser ignores the UTF-8-ness of C<PL_rsfp>, or any SVs returned from |
677 | source filters. All this could be fixed. |
678 | |
f092b1f4 |
679 | =head2 The yada yada yada operators |
680 | |
681 | Perl 6's Synopsis 3 says: |
682 | |
683 | I<The ... operator is the "yada, yada, yada" list operator, which is used as |
684 | the body in function prototypes. It complains bitterly (by calling fail) |
685 | if it is ever executed. Variant ??? calls warn, and !!! calls die.> |
686 | |
687 | Those would be nice to add to Perl 5. That could be done without new ops. |
688 | |
87a942b1 |
689 | =head2 Virtualize operating system access |
690 | |
691 | Implement a set of "vtables" that virtualizes operating system access |
692 | (open(), mkdir(), unlink(), readdir(), getenv(), etc.) At the very |
693 | least these interfaces should take SVs as "name" arguments instead of |
694 | bare char pointers; probably the most flexible and extensible way |
e1a3d5d1 |
695 | would be for the Perl-facing interfaces to accept HVs. The system |
696 | needs to be per-operating-system and per-file-system |
697 | hookable/filterable, preferably both from XS and Perl level |
87a942b1 |
698 | (L<perlport/"Files and Filesystems"> is good reading at this point, |
699 | in fact, all of L<perlport> is.) |
700 | |
e1a3d5d1 |
701 | This has actually already been implemented (but only for Win32), |
702 | take a look at F<iperlsys.h> and F<win32/perlhost.h>. While all Win32 |
703 | variants go through a set of "vtables" for operating system access, |
704 | non-Win32 systems currently go straight for the POSIX/UNIX-style |
705 | system/library call. Similar system as for Win32 should be |
706 | implemented for all platforms. The existing Win32 implementation |
707 | probably does not need to survive alongside this proposed new |
708 | implementation, the approaches could be merged. |
87a942b1 |
709 | |
710 | What would this give us? One often-asked-for feature this would |
94da6c29 |
711 | enable is using Unicode for filenames, and other "names" like %ENV, |
712 | usernames, hostnames, and so forth. |
713 | (See L<perlunicode/"When Unicode Does Not Happen">.) |
714 | |
715 | But this kind of virtualization would also allow for things like |
716 | virtual filesystems, virtual networks, and "sandboxes" (though as long |
717 | as dynamic loading of random object code is allowed, not very safe |
718 | sandboxes since external code of course know not of Perl's vtables). |
719 | An example of a smaller "sandbox" is that this feature can be used to |
720 | implement per-thread working directories: Win32 already does this. |
721 | |
722 | See also L</"Extend PerlIO and PerlIO::Scalar">. |
87a942b1 |
723 | |
0bdfc961 |
724 | =head1 Big projects |
725 | |
726 | Tasks that will get your name mentioned in the description of the "Highlights |
87a942b1 |
727 | of 5.12" |
0bdfc961 |
728 | |
729 | =head2 make ithreads more robust |
730 | |
4e577f8b |
731 | Generally make ithreads more robust. See also L</iCOW> |
0bdfc961 |
732 | |
733 | This task is incremental - even a little bit of work on it will help, and |
734 | will be greatly appreciated. |
735 | |
6c047da7 |
736 | One bit would be to write the missing code in sv.c:Perl_dirp_dup. |
737 | |
59c7f7d5 |
738 | Fix Perl_sv_dup, et al so that threads can return objects. |
739 | |
0bdfc961 |
740 | =head2 iCOW |
741 | |
742 | Sarathy and Arthur have a proposal for an improved Copy On Write which |
743 | specifically will be able to COW new ithreads. If this can be implemented |
744 | it would be a good thing. |
745 | |
746 | =head2 (?{...}) closures in regexps |
747 | |
748 | Fix (or rewrite) the implementation of the C</(?{...})/> closures. |
749 | |
750 | =head2 A re-entrant regexp engine |
751 | |
752 | This will allow the use of a regex from inside (?{ }), (??{ }) and |
753 | (?(?{ })|) constructs. |
6bda09f9 |
754 | |
6bda09f9 |
755 | =head2 Add class set operations to regexp engine |
756 | |
757 | Apparently these are quite useful. Anyway, Jeffery Friedl wants them. |
758 | |
759 | demerphq has this on his todo list, but right at the bottom. |