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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 | |
412f19a0 |
25 | =head2 merge common code in installperl and installman |
26 | |
27 | There are some common subroutines and a common C<BEGIN> block in F<installperl> |
28 | and F<installman>. These should probably be merged. It would also be good to |
29 | check for duplication in all the utility scripts supplied in the source |
30 | tarball. It might be good to move them all to a subdirectory, but this would |
31 | require careful checking to find all places that call them, and change those |
32 | correctly. |
33 | |
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34 | =head2 common test code for timed bail out |
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35 | |
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36 | Write portable self destruct code for tests to stop them burning CPU in |
37 | infinite loops. This needs to avoid using alarm, as some of the tests are |
38 | testing alarm/sleep or timers. |
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39 | |
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40 | =head2 POD -E<gt> HTML conversion in the core still sucks |
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41 | |
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42 | Which is crazy given just how simple POD purports to be, and how simple HTML |
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43 | can be. It's not actually I<as> simple as it sounds, particularly with the |
44 | flexibility POD allows for C<=item>, but it would be good to improve the |
45 | visual appeal of the HTML generated, and to avoid it having any validation |
46 | errors. See also L</make HTML install work>, as the layout of installation tree |
47 | is needed to improve the cross-linking. |
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48 | |
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49 | The addition of C<Pod::Simple> and its related modules may make this task |
50 | easier to complete. |
51 | |
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52 | =head2 merge checkpods and podchecker |
53 | |
54 | F<pod/checkpods.PL> (and C<make check> in the F<pod/> subdirectory) |
55 | implements a very basic check for pod files, but the errors it discovers |
56 | aren't found by podchecker. Add this check to podchecker, get rid of |
57 | checkpods and have C<make check> use podchecker. |
58 | |
b032e2ff |
59 | =head2 perlmodlib.PL rewrite |
60 | |
61 | Currently perlmodlib.PL needs to be run from a source directory where perl |
62 | has been built, or some modules won't be found, and others will be |
63 | skipped. Make it run from a clean perl source tree (so it's reproducible). |
64 | |
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65 | =head2 Parallel testing |
66 | |
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67 | (This probably impacts much more than the core: also the Test::Harness |
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68 | and TAP::* modules on CPAN.) |
69 | |
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70 | The core regression test suite is getting ever more comprehensive, which has |
71 | the side effect that it takes longer to run. This isn't so good. Investigate |
72 | whether it would be feasible to give the harness script the B<option> of |
73 | running sets of tests in parallel. This would be useful for tests in |
74 | F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>. |
75 | |
76 | Questions to answer |
77 | |
78 | =over 4 |
79 | |
80 | =item 1 |
81 | |
82 | How does screen layout work when you're running more than one test? |
83 | |
84 | =item 2 |
85 | |
86 | How does the caller of test specify how many tests to run in parallel? |
87 | |
88 | =item 3 |
89 | |
90 | How do setup/teardown tests identify themselves? |
91 | |
92 | =back |
93 | |
94 | Pugs already does parallel testing - can their approach be re-used? |
95 | |
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96 | =head2 Make Schwern poorer |
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97 | |
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98 | We should have tests for everything. When all the core's modules are tested, |
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99 | Schwern has promised to donate to $500 to TPF. We may need volunteers to |
100 | hold him upside down and shake vigorously in order to actually extract the |
101 | cash. |
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102 | |
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103 | =head2 Improve the coverage of the core tests |
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104 | |
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105 | Use Devel::Cover to ascertain the core modules's test coverage, then add |
106 | tests that are currently missing. |
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107 | |
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108 | =head2 test B |
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109 | |
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110 | A full test suite for the B module would be nice. |
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111 | |
636e63cb |
112 | =head2 Deparse inlined constants |
113 | |
114 | Code such as this |
115 | |
116 | use constant PI => 4; |
117 | warn PI |
118 | |
119 | will currently deparse as |
120 | |
121 | use constant ('PI', 4); |
122 | warn 4; |
123 | |
124 | because the tokenizer inlines the value of the constant subroutine C<PI>. |
125 | This allows various compile time optimisations, such as constant folding |
126 | and dead code elimination. Where these haven't happened (such as the example |
127 | above) it ought be possible to make B::Deparse work out the name of the |
128 | original constant, because just enough information survives in the symbol |
129 | table to do this. Specifically, the same scalar is used for the constant in |
130 | the optree as is used for the constant subroutine, so by iterating over all |
131 | symbol tables and generating a mapping of SV address to constant name, it |
132 | would be possible to provide B::Deparse with this functionality. |
133 | |
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134 | =head2 A decent benchmark |
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135 | |
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136 | C<perlbench> seems impervious to any recent changes made to the perl core. It |
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137 | would be useful to have a reasonable general benchmarking suite that roughly |
138 | represented what current perl programs do, and measurably reported whether |
139 | tweaks to the core improve, degrade or don't really affect performance, to |
140 | guide people attempting to optimise the guts of perl. Gisle would welcome |
141 | new tests for perlbench. |
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142 | |
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143 | =head2 fix tainting bugs |
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144 | |
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145 | Fix the bugs revealed by running the test suite with the C<-t> switch (via |
146 | C<make test.taintwarn>). |
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147 | |
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148 | =head2 Dual life everything |
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149 | |
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150 | As part of the "dists" plan, anything that doesn't belong in the smallest perl |
151 | distribution needs to be dual lifed. Anything else can be too. Figure out what |
152 | changes would be needed to package that module and its tests up for CPAN, and |
153 | do so. Test it with older perl releases, and fix the problems you find. |
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154 | |
a393eb28 |
155 | To make a minimal perl distribution, it's useful to look at |
156 | F<t/lib/commonsense.t>. |
157 | |
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158 | =head2 Improving C<threads::shared> |
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159 | |
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160 | Investigate whether C<threads::shared> could share aggregates properly with |
161 | only Perl level changes to shared.pm |
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162 | |
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163 | =head2 POSIX memory footprint |
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164 | |
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165 | Ilya observed that use POSIX; eats memory like there's no tomorrow, and at |
166 | various times worked to cut it down. There is probably still fat to cut out - |
167 | for example POSIX passes Exporter some very memory hungry data structures. |
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168 | |
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169 | =head2 embed.pl/makedef.pl |
170 | |
171 | There is a script F<embed.pl> that generates several header files to prefix |
172 | all of Perl's symbols in a consistent way, to provide some semblance of |
173 | namespace support in C<C>. Functions are declared in F<embed.fnc>, variables |
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174 | in F<interpvar.h>. Quite a few of the functions and variables |
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175 | are conditionally declared there, using C<#ifdef>. However, F<embed.pl> |
176 | doesn't understand the C macros, so the rules about which symbols are present |
177 | when is duplicated in F<makedef.pl>. Writing things twice is bad, m'kay. |
178 | It would be good to teach C<embed.pl> to understand the conditional |
179 | compilation, and hence remove the duplication, and the mistakes it has caused. |
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180 | |
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181 | =head2 use strict; and AutoLoad |
182 | |
183 | Currently if you write |
184 | |
185 | package Whack; |
186 | use AutoLoader 'AUTOLOAD'; |
187 | use strict; |
188 | 1; |
189 | __END__ |
190 | sub bloop { |
191 | print join (' ', No, strict, here), "!\n"; |
192 | } |
193 | |
194 | then C<use strict;> isn't in force within the autoloaded subroutines. It would |
195 | be more consistent (and less surprising) to arrange for all lexical pragmas |
196 | in force at the __END__ block to be in force within each autoloaded subroutine. |
197 | |
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198 | There's a similar problem with SelfLoader. |
199 | |
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200 | =head1 Tasks that need a little sysadmin-type knowledge |
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201 | |
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202 | Or if you prefer, tasks that you would learn from, and broaden your skills |
203 | base... |
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204 | |
cd793d32 |
205 | =head2 make HTML install work |
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206 | |
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207 | There is an C<installhtml> target in the Makefile. It's marked as |
208 | "experimental". It would be good to get this tested, make it work reliably, and |
209 | remove the "experimental" tag. This would include |
210 | |
211 | =over 4 |
212 | |
213 | =item 1 |
214 | |
215 | Checking that cross linking between various parts of the documentation works. |
216 | In particular that links work between the modules (files with POD in F<lib/>) |
217 | and the core documentation (files in F<pod/>) |
218 | |
219 | =item 2 |
220 | |
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221 | Work out how to split C<perlfunc> into chunks, preferably one per function |
222 | group, preferably with general case code that could be used elsewhere. |
223 | Challenges here are correctly identifying the groups of functions that go |
224 | together, and making the right named external cross-links point to the right |
225 | page. Things to be aware of are C<-X>, groups such as C<getpwnam> to |
226 | C<endservent>, two or more C<=items> giving the different parameter lists, such |
227 | as |
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228 | |
229 | =item substr EXPR,OFFSET,LENGTH,REPLACEMENT |
adebf063 |
230 | =item substr EXPR,OFFSET,LENGTH |
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231 | =item substr EXPR,OFFSET |
232 | |
233 | and different parameter lists having different meanings. (eg C<select>) |
234 | |
235 | =back |
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236 | |
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237 | =head2 compressed man pages |
238 | |
239 | Be able to install them. This would probably need a configure test to see how |
240 | the system does compressed man pages (same directory/different directory? |
241 | same filename/different filename), as well as tweaking the F<installman> script |
242 | to compress as necessary. |
243 | |
30222c0f |
244 | =head2 Add a code coverage target to the Makefile |
245 | |
246 | Make it easy for anyone to run Devel::Cover on the core's tests. The steps |
247 | to do this manually are roughly |
248 | |
249 | =over 4 |
250 | |
251 | =item * |
252 | |
253 | do a normal C<Configure>, but include Devel::Cover as a module to install |
254 | (see F<INSTALL> for how to do this) |
255 | |
256 | =item * |
257 | |
258 | make perl |
259 | |
260 | =item * |
261 | |
262 | cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness |
263 | |
264 | =item * |
265 | |
266 | Process the resulting Devel::Cover database |
267 | |
268 | =back |
269 | |
270 | This just give you the coverage of the F<.pm>s. To also get the C level |
271 | coverage you need to |
272 | |
273 | =over 4 |
274 | |
275 | =item * |
276 | |
277 | Additionally tell C<Configure> to use the appropriate C compiler flags for |
278 | C<gcov> |
279 | |
280 | =item * |
281 | |
282 | make perl.gcov |
283 | |
284 | (instead of C<make perl>) |
285 | |
286 | =item * |
287 | |
288 | After running the tests run C<gcov> to generate all the F<.gcov> files. |
289 | (Including down in the subdirectories of F<ext/> |
290 | |
291 | =item * |
292 | |
293 | (From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files |
294 | to get their stats into the cover_db directory. |
295 | |
296 | =item * |
297 | |
298 | Then process the Devel::Cover database |
299 | |
300 | =back |
301 | |
302 | It would be good to add a single switch to C<Configure> to specify that you |
303 | wanted to perform perl level coverage, and another to specify C level |
304 | coverage, and have C<Configure> and the F<Makefile> do all the right things |
305 | automatically. |
306 | |
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307 | =head2 Make Config.pm cope with differences between built and installed perl |
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308 | |
309 | Quite often vendors ship a perl binary compiled with their (pay-for) |
310 | compilers. People install a free compiler, such as gcc. To work out how to |
311 | build extensions, Perl interrogates C<%Config>, so in this situation |
312 | C<%Config> describes compilers that aren't there, and extension building |
313 | fails. This forces people into choosing between re-compiling perl themselves |
314 | using the compiler they have, or only using modules that the vendor ships. |
315 | |
316 | It would be good to find a way teach C<Config.pm> about the installation setup, |
317 | possibly involving probing at install time or later, so that the C<%Config> in |
318 | a binary distribution better describes the installed machine, when the |
319 | installed machine differs from the build machine in some significant way. |
320 | |
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321 | =head2 linker specification files |
322 | |
323 | Some platforms mandate that you provide a list of a shared library's external |
324 | symbols to the linker, so the core already has the infrastructure in place to |
325 | do this for generating shared perl libraries. My understanding is that the |
326 | GNU toolchain can accept an optional linker specification file, and restrict |
327 | visibility just to symbols declared in that file. It would be good to extend |
328 | F<makedef.pl> to support this format, and to provide a means within |
329 | C<Configure> to enable it. This would allow Unix users to test that the |
330 | export list is correct, and to build a perl that does not pollute the global |
331 | namespace with private symbols. |
332 | |
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333 | =head2 Cross-compile support |
334 | |
335 | Currently C<Configure> understands C<-Dusecrosscompile> option. This option |
336 | arranges for building C<miniperl> for TARGET machine, so this C<miniperl> is |
337 | assumed then to be copied to TARGET machine and used as a replacement of full |
338 | C<perl> executable. |
339 | |
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340 | This could be done little differently. Namely C<miniperl> should be built for |
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341 | HOST and then full C<perl> with extensions should be compiled for TARGET. |
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342 | This, however, might require extra trickery for %Config: we have one config |
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343 | first for HOST and then another for TARGET. Tools like MakeMaker will be |
344 | mightily confused. Having around two different types of executables and |
345 | libraries (HOST and TARGET) makes life interesting for Makefiles and |
346 | shell (and Perl) scripts. There is $Config{run}, normally empty, which |
347 | can be used as an execution wrapper. Also note that in some |
348 | cross-compilation/execution environments the HOST and the TARGET do |
349 | not see the same filesystem(s), the $Config{run} may need to do some |
350 | file/directory copying back and forth. |
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351 | |
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352 | =head2 roffitall |
353 | |
354 | Make F<pod/roffitall> be updated by F<pod/buildtoc>. |
355 | |
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356 | =head1 Tasks that need a little C knowledge |
357 | |
358 | These tasks would need a little C knowledge, but don't need any specific |
359 | background or experience with XS, or how the Perl interpreter works |
360 | |
99d50c9c |
361 | =head2 Exterminate PL_na! |
362 | |
363 | C<PL_na> festers still in the darkest corners of various typemap files. |
364 | It needs to be exterminated, replaced by a local variable of type C<STRLEN>. |
365 | |
fbf638cb |
366 | =head2 Modernize the order of directories in @INC |
367 | |
368 | The way @INC is laid out by default, one cannot upgrade core (dual-life) |
369 | modules without overwriting files. This causes problems for binary |
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370 | package builders. One possible proposal is laid out in this |
371 | message: |
372 | L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-04/msg02380.html>. |
fbf638cb |
373 | |
bcbaa2d5 |
374 | =head2 -Duse32bit* |
375 | |
376 | Natively 64-bit systems need neither -Duse64bitint nor -Duse64bitall. |
377 | On these systems, it might be the default compilation mode, and there |
378 | is currently no guarantee that passing no use64bitall option to the |
379 | Configure process will build a 32bit perl. Implementing -Duse32bit* |
380 | options would be nice for perl 5.12. |
381 | |
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382 | =head2 Make it clear from -v if this is the exact official release |
89007cb3 |
383 | |
617eabfa |
384 | Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that |
385 | usually defines one local patch, of the form "MAINT12345" or "RC1". The output |
386 | of perl -v doesn't report that a perl isn't an official release, and this |
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387 | information can get lost in bugs reports. Because of this, the minor version |
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388 | isn't bumped up until RC time, to minimise the possibility of versions of perl |
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389 | escaping that believe themselves to be newer than they actually are. |
390 | |
391 | It would be useful to find an elegant way to have the "this is an interim |
392 | maintenance release" or "this is a release candidate" in the terse -v output, |
393 | and have it so that it's easy for the pumpking to remove this just as the |
394 | release tarball is rolled up. This way the version pulled out of rsync would |
395 | always say "I'm a development release" and it would be safe to bump the |
396 | reported minor version as soon as a release ships, which would aid perl |
397 | developers. |
398 | |
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399 | This task is really about thinking of an elegant way to arrange the C source |
400 | such that it's trivial for the Pumpking to flag "this is an official release" |
401 | when making a tarball, yet leave the default source saying "I'm not the |
402 | official release". |
403 | |
fee0a0f7 |
404 | =head2 Profile Perl - am I hot or not? |
62403a3c |
405 | |
fee0a0f7 |
406 | The Perl source code is stable enough that it makes sense to profile it, |
407 | identify and optimise the hotspots. It would be good to measure the |
408 | performance of the Perl interpreter using free tools such as cachegrind, |
409 | gprof, and dtrace, and work to reduce the bottlenecks they reveal. |
410 | |
411 | As part of this, the idea of F<pp_hot.c> is that it contains the I<hot> ops, |
412 | the ops that are most commonly used. The idea is that by grouping them, their |
413 | object code will be adjacent in the executable, so they have a greater chance |
414 | of already being in the CPU cache (or swapped in) due to being near another op |
415 | already in use. |
62403a3c |
416 | |
417 | Except that it's not clear if these really are the most commonly used ops. So |
fee0a0f7 |
418 | as part of exercising your skills with coverage and profiling tools you might |
419 | want to determine what ops I<really> are the most commonly used. And in turn |
420 | suggest evictions and promotions to achieve a better F<pp_hot.c>. |
62403a3c |
421 | |
98fed0ad |
422 | =head2 Allocate OPs from arenas |
423 | |
424 | Currently all new OP structures are individually malloc()ed and free()d. |
425 | All C<malloc> implementations have space overheads, and are now as fast as |
426 | custom allocates so it would both use less memory and less CPU to allocate |
427 | the various OP structures from arenas. The SV arena code can probably be |
428 | re-used for this. |
429 | |
539f2c54 |
430 | Note that Configuring perl with C<-Accflags=-DPL_OP_SLAB_ALLOC> will use |
431 | Perl_Slab_alloc() to pack optrees into a contiguous block, which is |
432 | probably superior to the use of OP arenas, esp. from a cache locality |
433 | standpoint. See L<Profile Perl - am I hot or not?>. |
434 | |
a229ae3b |
435 | =head2 Improve win32/wince.c |
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436 | |
a229ae3b |
437 | Currently, numerous functions look virtually, if not completely, |
02f21748 |
438 | identical in both C<win32/wince.c> and C<win32/win32.c> files, which can't |
6d71adcd |
439 | be good. |
440 | |
c5b31784 |
441 | =head2 Use secure CRT functions when building with VC8 on Win32 |
442 | |
443 | Visual C++ 2005 (VC++ 8.x) deprecated a number of CRT functions on the basis |
444 | that they were "unsafe" and introduced differently named secure versions of |
445 | them as replacements, e.g. instead of writing |
446 | |
447 | FILE* f = fopen(__FILE__, "r"); |
448 | |
449 | one should now write |
450 | |
451 | FILE* f; |
452 | errno_t err = fopen_s(&f, __FILE__, "r"); |
453 | |
454 | Currently, the warnings about these deprecations have been disabled by adding |
455 | -D_CRT_SECURE_NO_DEPRECATE to the CFLAGS. It would be nice to remove that |
456 | warning suppressant and actually make use of the new secure CRT functions. |
457 | |
458 | There is also a similar issue with POSIX CRT function names like fileno having |
459 | been deprecated in favour of ISO C++ conformant names like _fileno. These |
26a6faa8 |
460 | warnings are also currently suppressed by adding -D_CRT_NONSTDC_NO_DEPRECATE. It |
c5b31784 |
461 | might be nice to do as Microsoft suggest here too, although, unlike the secure |
462 | functions issue, there is presumably little or no benefit in this case. |
463 | |
6b632b43 |
464 | =head2 __FUNCTION__ for MSVC-pre-7.0 |
465 | |
466 | Jarkko notes that one can things morally equivalent to C<__FUNCTION__> |
467 | (or C<__func__>) even in MSVC-pre-7.0, contrary to popular belief. |
468 | See L<http://www.codeproject.com/debug/extendedtrace.asp> if you feel like |
469 | making C<PERL_MEM_LOG> more useful on Win32. |
470 | |
16815324 |
471 | =head2 strcat(), strcpy(), strncat(), strncpy(), sprintf(), vsprintf() |
472 | |
473 | Maybe create a utility that checks after each libperl.a creation that |
474 | none of the above (nor sprintf(), vsprintf(), or *SHUDDER* gets()) |
475 | ever creep back to libperl.a. |
476 | |
477 | nm libperl.a | ./miniperl -alne '$o = $F[0] if /:$/; print "$o $F[1]" if $F[0] eq "U" && $F[1] =~ /^(?:strn?c(?:at|py)|v?sprintf|gets)$/' |
478 | |
479 | Note, of course, that this will only tell whether B<your> platform |
480 | is using those naughty interfaces. |
481 | |
482 | |
6d71adcd |
483 | =head1 Tasks that need a knowledge of XS |
484 | |
485 | These tasks would need C knowledge, and roughly the level of knowledge of |
486 | the perl API that comes from writing modules that use XS to interface to |
487 | C. |
488 | |
6d71adcd |
489 | =head2 autovivification |
490 | |
491 | Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict; |
492 | |
493 | This task is incremental - even a little bit of work on it will help. |
494 | |
495 | =head2 Unicode in Filenames |
496 | |
497 | chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open, |
498 | opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen, |
499 | system, truncate, unlink, utime, -X. All these could potentially accept |
500 | Unicode filenames either as input or output (and in the case of system |
501 | and qx Unicode in general, as input or output to/from the shell). |
502 | Whether a filesystem - an operating system pair understands Unicode in |
503 | filenames varies. |
504 | |
505 | Known combinations that have some level of understanding include |
506 | Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac |
507 | OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to |
508 | create Unicode filenames, what forms of Unicode are accepted and used |
509 | (UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used, |
510 | and so on, varies. Finding the right level of interfacing to Perl |
511 | requires some thought. Remember that an OS does not implicate a |
512 | filesystem. |
513 | |
514 | (The Windows -C command flag "wide API support" has been at least |
515 | temporarily retired in 5.8.1, and the -C has been repurposed, see |
516 | L<perlrun>.) |
517 | |
87a942b1 |
518 | Most probably the right way to do this would be this: |
519 | L</"Virtualize operating system access">. |
520 | |
6d71adcd |
521 | =head2 Unicode in %ENV |
522 | |
523 | Currently the %ENV entries are always byte strings. |
87a942b1 |
524 | See L</"Virtualize operating system access">. |
6d71adcd |
525 | |
1f2e7916 |
526 | =head2 Unicode and glob() |
527 | |
528 | Currently glob patterns and filenames returned from File::Glob::glob() |
87a942b1 |
529 | are always byte strings. See L</"Virtualize operating system access">. |
1f2e7916 |
530 | |
dbb0c492 |
531 | =head2 Unicode and lc/uc operators |
532 | |
533 | Some built-in operators (C<lc>, C<uc>, etc.) behave differently, based on |
534 | what the internal encoding of their argument is. That should not be the |
535 | case. Maybe add a pragma to switch behaviour. |
536 | |
6d71adcd |
537 | =head2 use less 'memory' |
538 | |
539 | Investigate trade offs to switch out perl's choices on memory usage. |
540 | Particularly perl should be able to give memory back. |
541 | |
542 | This task is incremental - even a little bit of work on it will help. |
543 | |
544 | =head2 Re-implement C<:unique> in a way that is actually thread-safe |
545 | |
546 | The old implementation made bad assumptions on several levels. A good 90% |
547 | solution might be just to make C<:unique> work to share the string buffer |
548 | of SvPVs. That way large constant strings can be shared between ithreads, |
549 | such as the configuration information in F<Config>. |
550 | |
551 | =head2 Make tainting consistent |
552 | |
553 | Tainting would be easier to use if it didn't take documented shortcuts and |
554 | allow taint to "leak" everywhere within an expression. |
555 | |
556 | =head2 readpipe(LIST) |
557 | |
558 | system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid |
559 | running a shell. readpipe() (the function behind qx//) could be similarly |
560 | extended. |
561 | |
6d71adcd |
562 | =head2 Audit the code for destruction ordering assumptions |
563 | |
564 | Change 25773 notes |
565 | |
566 | /* Need to check SvMAGICAL, as during global destruction it may be that |
567 | AvARYLEN(av) has been freed before av, and hence the SvANY() pointer |
568 | is now part of the linked list of SV heads, rather than pointing to |
569 | the original body. */ |
570 | /* FIXME - audit the code for other bugs like this one. */ |
571 | |
572 | adding the C<SvMAGICAL> check to |
573 | |
574 | if (AvARYLEN(av) && SvMAGICAL(AvARYLEN(av))) { |
575 | MAGIC *mg = mg_find (AvARYLEN(av), PERL_MAGIC_arylen); |
576 | |
577 | Go through the core and look for similar assumptions that SVs have particular |
578 | types, as all bets are off during global destruction. |
579 | |
749904bf |
580 | =head2 Extend PerlIO and PerlIO::Scalar |
581 | |
582 | PerlIO::Scalar doesn't know how to truncate(). Implementing this |
583 | would require extending the PerlIO vtable. |
584 | |
585 | Similarly the PerlIO vtable doesn't know about formats (write()), or |
586 | about stat(), or chmod()/chown(), utime(), or flock(). |
587 | |
588 | (For PerlIO::Scalar it's hard to see what e.g. mode bits or ownership |
589 | would mean.) |
590 | |
591 | PerlIO doesn't do directories or symlinks, either: mkdir(), rmdir(), |
592 | opendir(), closedir(), seekdir(), rewinddir(), glob(); symlink(), |
593 | readlink(). |
594 | |
94da6c29 |
595 | See also L</"Virtualize operating system access">. |
596 | |
3236f110 |
597 | =head2 -C on the #! line |
598 | |
599 | It should be possible to make -C work correctly if found on the #! line, |
600 | given that all perl command line options are strict ASCII, and -C changes |
601 | only the interpretation of non-ASCII characters, and not for the script file |
602 | handle. To make it work needs some investigation of the ordering of function |
603 | calls during startup, and (by implication) a bit of tweaking of that order. |
604 | |
81622873 |
605 | =head2 Propagate const outwards from Perl_moreswitches() |
606 | |
607 | Change 32057 changed the parameter and return value of C<Perl_moreswitches()> |
608 | from <char *> to <const char *>. It should now be possible to propagate |
609 | const-correctness outwards to C<S_parse_body()>, C<Perl_moreswitches()> |
610 | and C<Perl_yylex()>. |
611 | |
16815324 |
612 | =head2 Duplicate logic in S_method_common() and Perl_gv_fetchmethod_autoload() |
613 | |
614 | A comment in C<S_method_common> notes |
615 | |
616 | /* This code tries to figure out just what went wrong with |
617 | gv_fetchmethod. It therefore needs to duplicate a lot of |
618 | the internals of that function. We can't move it inside |
619 | Perl_gv_fetchmethod_autoload(), however, since that would |
620 | cause UNIVERSAL->can("NoSuchPackage::foo") to croak, and we |
621 | don't want that. |
622 | */ |
623 | |
624 | If C<Perl_gv_fetchmethod_autoload> gets rewritten to take (more) flag bits, |
625 | then it ought to be possible to move the logic from C<S_method_common> to |
626 | the "right" place. When making this change it would probably be good to also |
627 | pass in at least the method name length, if not also pre-computed hash values |
628 | when known. (I'm contemplating a plan to pre-compute hash values for common |
629 | fixed strings such as C<ISA> and pass them in to functions.) |
630 | |
3236f110 |
631 | |
0bdfc961 |
632 | =head1 Tasks that need a knowledge of the interpreter |
3298bd4d |
633 | |
0bdfc961 |
634 | These tasks would need C knowledge, and knowledge of how the interpreter works, |
635 | or a willingness to learn. |
3298bd4d |
636 | |
636e63cb |
637 | =head2 state variable initialization in list context |
638 | |
639 | Currently this is illegal: |
640 | |
641 | state ($a, $b) = foo(); |
642 | |
643 | The current Perl 6 design is that C<state ($a) = foo();> and |
644 | C<(state $a) = foo();> have different semantics, which is tricky to implement |
645 | in Perl 5 as currently the produce the same opcode trees. It would be useful |
646 | to clarify that the Perl 6 design is firm, and then implement the necessary |
647 | code in Perl 5. There are comments in C<Perl_newASSIGNOP()> that show the |
648 | code paths taken by various assignment constructions involving state variables. |
649 | |
4fedb12c |
650 | =head2 Implement $value ~~ 0 .. $range |
651 | |
652 | It would be nice to extend the syntax of the C<~~> operator to also |
653 | understand numeric (and maybe alphanumeric) ranges. |
a393eb28 |
654 | |
655 | =head2 A does() built-in |
656 | |
657 | Like ref(), only useful. It would call the C<DOES> method on objects; it |
658 | would also tell whether something can be dereferenced as an |
659 | array/hash/etc., or used as a regexp, etc. |
660 | L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-03/msg00481.html> |
661 | |
662 | =head2 Tied filehandles and write() don't mix |
663 | |
664 | There is no method on tied filehandles to allow them to be called back by |
665 | formats. |
4fedb12c |
666 | |
d10fc472 |
667 | =head2 Attach/detach debugger from running program |
1626a787 |
668 | |
cd793d32 |
669 | The old perltodo notes "With C<gdb>, you can attach the debugger to a running |
670 | program if you pass the process ID. It would be good to do this with the Perl |
0bdfc961 |
671 | debugger on a running Perl program, although I'm not sure how it would be |
672 | done." ssh and screen do this with named pipes in /tmp. Maybe we can too. |
1626a787 |
673 | |
a8cb5b9e |
674 | =head2 Optimize away empty destructors |
675 | |
676 | Defining an empty DESTROY method might be useful (notably in |
677 | AUTOLOAD-enabled classes), but it's still a bit expensive to call. That |
678 | could probably be optimized. |
679 | |
0bdfc961 |
680 | =head2 LVALUE functions for lists |
681 | |
682 | The old perltodo notes that lvalue functions don't work for list or hash |
683 | slices. This would be good to fix. |
684 | |
685 | =head2 LVALUE functions in the debugger |
686 | |
687 | The old perltodo notes that lvalue functions don't work in the debugger. This |
688 | would be good to fix. |
689 | |
0bdfc961 |
690 | =head2 regexp optimiser optional |
691 | |
692 | The regexp optimiser is not optional. It should configurable to be, to allow |
693 | its performance to be measured, and its bugs to be easily demonstrated. |
694 | |
02f21748 |
695 | =head2 delete &function |
696 | |
697 | Allow to delete functions. One can already undef them, but they're still |
698 | in the stash. |
699 | |
ef36c6a7 |
700 | =head2 C</w> regex modifier |
701 | |
702 | That flag would enable to match whole words, and also to interpolate |
703 | arrays as alternations. With it, C</P/w> would be roughly equivalent to: |
704 | |
705 | do { local $"='|'; /\b(?:P)\b/ } |
706 | |
707 | See L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-01/msg00400.html> |
708 | for the discussion. |
709 | |
0bdfc961 |
710 | =head2 optional optimizer |
711 | |
712 | Make the peephole optimizer optional. Currently it performs two tasks as |
713 | it walks the optree - genuine peephole optimisations, and necessary fixups of |
714 | ops. It would be good to find an efficient way to switch out the |
715 | optimisations whilst keeping the fixups. |
716 | |
717 | =head2 You WANT *how* many |
718 | |
719 | Currently contexts are void, scalar and list. split has a special mechanism in |
720 | place to pass in the number of return values wanted. It would be useful to |
721 | have a general mechanism for this, backwards compatible and little speed hit. |
722 | This would allow proposals such as short circuiting sort to be implemented |
723 | as a module on CPAN. |
724 | |
725 | =head2 lexical aliases |
726 | |
727 | Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>. |
728 | |
729 | =head2 entersub XS vs Perl |
730 | |
731 | At the moment pp_entersub is huge, and has code to deal with entering both |
732 | perl and XS subroutines. Subroutine implementations rarely change between |
733 | perl and XS at run time, so investigate using 2 ops to enter subs (one for |
734 | XS, one for perl) and swap between if a sub is redefined. |
2810d901 |
735 | |
736 | =head2 Self ties |
737 | |
738 | self ties are currently illegal because they caused too many segfaults. Maybe |
739 | the causes of these could be tracked down and self-ties on all types re- |
740 | instated. |
0bdfc961 |
741 | |
742 | =head2 Optimize away @_ |
743 | |
744 | The old perltodo notes "Look at the "reification" code in C<av.c>". |
745 | |
16fc99ce |
746 | =head2 Properly Unicode safe tokeniser and pads. |
747 | |
748 | The tokeniser isn't actually very UTF-8 clean. C<use utf8;> is a hack - |
749 | variable names are stored in stashes as raw bytes, without the utf-8 flag |
750 | set. The pad API only takes a C<char *> pointer, so that's all bytes too. The |
751 | tokeniser ignores the UTF-8-ness of C<PL_rsfp>, or any SVs returned from |
752 | source filters. All this could be fixed. |
753 | |
f092b1f4 |
754 | =head2 The yada yada yada operators |
755 | |
756 | Perl 6's Synopsis 3 says: |
757 | |
758 | I<The ... operator is the "yada, yada, yada" list operator, which is used as |
759 | the body in function prototypes. It complains bitterly (by calling fail) |
760 | if it is ever executed. Variant ??? calls warn, and !!! calls die.> |
761 | |
762 | Those would be nice to add to Perl 5. That could be done without new ops. |
763 | |
87a942b1 |
764 | =head2 Virtualize operating system access |
765 | |
766 | Implement a set of "vtables" that virtualizes operating system access |
767 | (open(), mkdir(), unlink(), readdir(), getenv(), etc.) At the very |
768 | least these interfaces should take SVs as "name" arguments instead of |
769 | bare char pointers; probably the most flexible and extensible way |
e1a3d5d1 |
770 | would be for the Perl-facing interfaces to accept HVs. The system |
771 | needs to be per-operating-system and per-file-system |
772 | hookable/filterable, preferably both from XS and Perl level |
87a942b1 |
773 | (L<perlport/"Files and Filesystems"> is good reading at this point, |
774 | in fact, all of L<perlport> is.) |
775 | |
e1a3d5d1 |
776 | This has actually already been implemented (but only for Win32), |
777 | take a look at F<iperlsys.h> and F<win32/perlhost.h>. While all Win32 |
778 | variants go through a set of "vtables" for operating system access, |
779 | non-Win32 systems currently go straight for the POSIX/UNIX-style |
780 | system/library call. Similar system as for Win32 should be |
781 | implemented for all platforms. The existing Win32 implementation |
782 | probably does not need to survive alongside this proposed new |
783 | implementation, the approaches could be merged. |
87a942b1 |
784 | |
785 | What would this give us? One often-asked-for feature this would |
94da6c29 |
786 | enable is using Unicode for filenames, and other "names" like %ENV, |
787 | usernames, hostnames, and so forth. |
788 | (See L<perlunicode/"When Unicode Does Not Happen">.) |
789 | |
790 | But this kind of virtualization would also allow for things like |
791 | virtual filesystems, virtual networks, and "sandboxes" (though as long |
792 | as dynamic loading of random object code is allowed, not very safe |
793 | sandboxes since external code of course know not of Perl's vtables). |
794 | An example of a smaller "sandbox" is that this feature can be used to |
795 | implement per-thread working directories: Win32 already does this. |
796 | |
797 | See also L</"Extend PerlIO and PerlIO::Scalar">. |
87a942b1 |
798 | |
ac6197af |
799 | =head2 Investigate PADTMP hash pessimisation |
800 | |
801 | The peephole optimier converts constants used for hash key lookups to shared |
802 | hash key scalars. Under ithreads, something is undoing this work. See |
803 | See http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-09/msg00793.html |
804 | |
0bdfc961 |
805 | =head1 Big projects |
806 | |
807 | Tasks that will get your name mentioned in the description of the "Highlights |
87a942b1 |
808 | of 5.12" |
0bdfc961 |
809 | |
810 | =head2 make ithreads more robust |
811 | |
4e577f8b |
812 | Generally make ithreads more robust. See also L</iCOW> |
0bdfc961 |
813 | |
814 | This task is incremental - even a little bit of work on it will help, and |
815 | will be greatly appreciated. |
816 | |
6c047da7 |
817 | One bit would be to write the missing code in sv.c:Perl_dirp_dup. |
818 | |
59c7f7d5 |
819 | Fix Perl_sv_dup, et al so that threads can return objects. |
820 | |
0bdfc961 |
821 | =head2 iCOW |
822 | |
823 | Sarathy and Arthur have a proposal for an improved Copy On Write which |
824 | specifically will be able to COW new ithreads. If this can be implemented |
825 | it would be a good thing. |
826 | |
827 | =head2 (?{...}) closures in regexps |
828 | |
829 | Fix (or rewrite) the implementation of the C</(?{...})/> closures. |
830 | |
831 | =head2 A re-entrant regexp engine |
832 | |
833 | This will allow the use of a regex from inside (?{ }), (??{ }) and |
834 | (?(?{ })|) constructs. |
6bda09f9 |
835 | |
6bda09f9 |
836 | =head2 Add class set operations to regexp engine |
837 | |
838 | Apparently these are quite useful. Anyway, Jeffery Friedl wants them. |
839 | |
840 | demerphq has this on his todo list, but right at the bottom. |