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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 | |
28 | =head2 Needed for a 5.9.3 release |
29 | |
30 | =over |
31 | |
32 | =item * |
33 | Implement L</lexical pragmas> |
34 | |
35 | =back |
36 | |
37 | =head2 Needed for a 5.9.4 release |
38 | |
39 | =over |
40 | |
41 | =item * |
42 | Review assertions. Review syntax to combine assertions. Can assertions take |
43 | advantage of the lexical pragams work? L</What hooks would assertions need?> |
44 | |
45 | =back |
46 | |
47 | =head2 Needed for a 5.9.5 release |
48 | |
49 | =over |
50 | |
51 | =item * |
52 | Implement L</_ prototype character> |
53 | |
54 | =item * |
55 | Implement L</state variables> |
56 | |
57 | =back |
58 | |
59 | =head2 Needed for a 5.9.6 release |
60 | |
61 | Stabilisation. If all goes well, this will be the equivalent of a 5.10-beta. |
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62 | |
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63 | =head1 Tasks that only need Perl knowledge |
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64 | |
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65 | =head2 common test code for timed bail out |
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66 | |
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67 | Write portable self destruct code for tests to stop them burning CPU in |
68 | infinite loops. This needs to avoid using alarm, as some of the tests are |
69 | testing alarm/sleep or timers. |
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70 | |
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71 | =head2 POD -> HTML conversion in the core still sucks |
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72 | |
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73 | Which is crazy given just how simple POD purports to be, and how simple HTML |
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74 | can be. It's not actually I<as> simple as it sounds, particularly with the |
75 | flexibility POD allows for C<=item>, but it would be good to improve the |
76 | visual appeal of the HTML generated, and to avoid it having any validation |
77 | errors. See also L</make HTML install work>, as the layout of installation tree |
78 | is needed to improve the cross-linking. |
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79 | |
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80 | =head2 Parallel testing |
81 | |
82 | The core regression test suite is getting ever more comprehensive, which has |
83 | the side effect that it takes longer to run. This isn't so good. Investigate |
84 | whether it would be feasible to give the harness script the B<option> of |
85 | running sets of tests in parallel. This would be useful for tests in |
86 | F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>. |
87 | |
88 | Questions to answer |
89 | |
90 | =over 4 |
91 | |
92 | =item 1 |
93 | |
94 | How does screen layout work when you're running more than one test? |
95 | |
96 | =item 2 |
97 | |
98 | How does the caller of test specify how many tests to run in parallel? |
99 | |
100 | =item 3 |
101 | |
102 | How do setup/teardown tests identify themselves? |
103 | |
104 | =back |
105 | |
106 | Pugs already does parallel testing - can their approach be re-used? |
107 | |
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108 | =head2 Make Schwern poorer |
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109 | |
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110 | We should have for everything. When all the core's modules are tested, |
111 | Schwern has promised to donate to $500 to TPF. We may need volunteers to |
112 | hold him upside down and shake vigorously in order to actually extract the |
113 | cash. |
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114 | |
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115 | See F<t/lib/1_compile.t> for the 3 remaining modules that need tests. |
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116 | |
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117 | =head2 Improve the coverage of the core tests |
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118 | |
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119 | Use Devel::Cover to ascertain the core's test coverage, then add tests that |
120 | are currently missing. |
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121 | |
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122 | =head2 test B |
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123 | |
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124 | A full test suite for the B module would be nice. |
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125 | |
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126 | =head2 A decent benchmark |
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127 | |
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128 | C<perlbench> seems impervious to any recent changes made to the perl core. It |
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129 | would be useful to have a reasonable general benchmarking suite that roughly |
130 | represented what current perl programs do, and measurably reported whether |
131 | tweaks to the core improve, degrade or don't really affect performance, to |
132 | guide people attempting to optimise the guts of perl. Gisle would welcome |
133 | new tests for perlbench. |
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134 | |
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135 | =head2 fix tainting bugs |
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136 | |
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137 | Fix the bugs revealed by running the test suite with the C<-t> switch (via |
138 | C<make test.taintwarn>). |
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139 | |
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140 | =head2 Dual life everything |
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141 | |
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142 | As part of the "dists" plan, anything that doesn't belong in the smallest perl |
143 | distribution needs to be dual lifed. Anything else can be too. Figure out what |
144 | changes would be needed to package that module and its tests up for CPAN, and |
145 | do so. Test it with older perl releases, and fix the problems you find. |
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146 | |
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147 | =head2 Improving C<threads::shared> |
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148 | |
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149 | Investigate whether C<threads::shared> could share aggregates properly with |
150 | only Perl level changes to shared.pm |
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151 | |
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152 | =head2 POSIX memory footprint |
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153 | |
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154 | Ilya observed that use POSIX; eats memory like there's no tomorrow, and at |
155 | various times worked to cut it down. There is probably still fat to cut out - |
156 | for example POSIX passes Exporter some very memory hungry data structures. |
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157 | |
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158 | |
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159 | |
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160 | |
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161 | |
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162 | |
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163 | |
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164 | =head1 Tasks that need a little sysadmin-type knowledge |
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165 | |
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166 | Or if you prefer, tasks that you would learn from, and broaden your skills |
167 | base... |
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168 | |
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169 | =head2 Relocatable perl |
170 | |
171 | The C level patches needed to create a relocatable perl binary are done, as |
172 | is the work on F<Config.pm>. All that's left to do is the C<Configure> tweaking |
173 | to let people specify how they want to do the install. |
174 | |
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175 | =head2 make HTML install work |
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176 | |
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177 | There is an C<installhtml> target in the Makefile. It's marked as |
178 | "experimental". It would be good to get this tested, make it work reliably, and |
179 | remove the "experimental" tag. This would include |
180 | |
181 | =over 4 |
182 | |
183 | =item 1 |
184 | |
185 | Checking that cross linking between various parts of the documentation works. |
186 | In particular that links work between the modules (files with POD in F<lib/>) |
187 | and the core documentation (files in F<pod/>) |
188 | |
189 | =item 2 |
190 | |
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191 | Work out how to split C<perlfunc> into chunks, preferably one per function |
192 | group, preferably with general case code that could be used elsewhere. |
193 | Challenges here are correctly identifying the groups of functions that go |
194 | together, and making the right named external cross-links point to the right |
195 | page. Things to be aware of are C<-X>, groups such as C<getpwnam> to |
196 | C<endservent>, two or more C<=items> giving the different parameter lists, such |
197 | as |
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198 | |
199 | =item substr EXPR,OFFSET,LENGTH,REPLACEMENT |
200 | |
201 | =item substr EXPR,OFFSET,LENGTH |
202 | |
203 | =item substr EXPR,OFFSET |
204 | |
205 | and different parameter lists having different meanings. (eg C<select>) |
206 | |
207 | =back |
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208 | |
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209 | =head2 compressed man pages |
210 | |
211 | Be able to install them. This would probably need a configure test to see how |
212 | the system does compressed man pages (same directory/different directory? |
213 | same filename/different filename), as well as tweaking the F<installman> script |
214 | to compress as necessary. |
215 | |
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216 | =head2 Add a code coverage target to the Makefile |
217 | |
218 | Make it easy for anyone to run Devel::Cover on the core's tests. The steps |
219 | to do this manually are roughly |
220 | |
221 | =over 4 |
222 | |
223 | =item * |
224 | |
225 | do a normal C<Configure>, but include Devel::Cover as a module to install |
226 | (see F<INSTALL> for how to do this) |
227 | |
228 | =item * |
229 | |
230 | make perl |
231 | |
232 | =item * |
233 | |
234 | cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness |
235 | |
236 | =item * |
237 | |
238 | Process the resulting Devel::Cover database |
239 | |
240 | =back |
241 | |
242 | This just give you the coverage of the F<.pm>s. To also get the C level |
243 | coverage you need to |
244 | |
245 | =over 4 |
246 | |
247 | =item * |
248 | |
249 | Additionally tell C<Configure> to use the appropriate C compiler flags for |
250 | C<gcov> |
251 | |
252 | =item * |
253 | |
254 | make perl.gcov |
255 | |
256 | (instead of C<make perl>) |
257 | |
258 | =item * |
259 | |
260 | After running the tests run C<gcov> to generate all the F<.gcov> files. |
261 | (Including down in the subdirectories of F<ext/> |
262 | |
263 | =item * |
264 | |
265 | (From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files |
266 | to get their stats into the cover_db directory. |
267 | |
268 | =item * |
269 | |
270 | Then process the Devel::Cover database |
271 | |
272 | =back |
273 | |
274 | It would be good to add a single switch to C<Configure> to specify that you |
275 | wanted to perform perl level coverage, and another to specify C level |
276 | coverage, and have C<Configure> and the F<Makefile> do all the right things |
277 | automatically. |
278 | |
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279 | =head2 Make Config.pm cope with differences between build and installed perl |
280 | |
281 | Quite often vendors ship a perl binary compiled with their (pay-for) |
282 | compilers. People install a free compiler, such as gcc. To work out how to |
283 | build extensions, Perl interrogates C<%Config>, so in this situation |
284 | C<%Config> describes compilers that aren't there, and extension building |
285 | fails. This forces people into choosing between re-compiling perl themselves |
286 | using the compiler they have, or only using modules that the vendor ships. |
287 | |
288 | It would be good to find a way teach C<Config.pm> about the installation setup, |
289 | possibly involving probing at install time or later, so that the C<%Config> in |
290 | a binary distribution better describes the installed machine, when the |
291 | installed machine differs from the build machine in some significant way. |
292 | |
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293 | =head2 make parallel builds work |
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294 | |
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295 | Currently parallel builds (such as C<make -j3>) don't work reliably. We believe |
296 | that this is due to incomplete dependency specification in the F<Makefile>. |
297 | It would be good if someone were able to track down the causes of these |
298 | problems, so that parallel builds worked properly. |
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299 | |
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300 | =head2 linker specification files |
301 | |
302 | Some platforms mandate that you provide a list of a shared library's external |
303 | symbols to the linker, so the core already has the infrastructure in place to |
304 | do this for generating shared perl libraries. My understanding is that the |
305 | GNU toolchain can accept an optional linker specification file, and restrict |
306 | visibility just to symbols declared in that file. It would be good to extend |
307 | F<makedef.pl> to support this format, and to provide a means within |
308 | C<Configure> to enable it. This would allow Unix users to test that the |
309 | export list is correct, and to build a perl that does not pollute the global |
310 | namespace with private symbols. |
311 | |
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312 | |
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313 | |
314 | |
315 | =head1 Tasks that need a little C knowledge |
316 | |
317 | These tasks would need a little C knowledge, but don't need any specific |
318 | background or experience with XS, or how the Perl interpreter works |
319 | |
320 | =head2 Make it clear from -v if this is the exact official release |
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321 | |
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322 | Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that |
323 | usually defines one local patch, of the form "MAINT12345" or "RC1". The output |
324 | of perl -v doesn't report that a perl isn't an official release, and this |
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325 | information can get lost in bugs reports. Because of this, the minor version |
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326 | isn't bumped up until RC time, to minimise the possibility of versions of perl |
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327 | escaping that believe themselves to be newer than they actually are. |
328 | |
329 | It would be useful to find an elegant way to have the "this is an interim |
330 | maintenance release" or "this is a release candidate" in the terse -v output, |
331 | and have it so that it's easy for the pumpking to remove this just as the |
332 | release tarball is rolled up. This way the version pulled out of rsync would |
333 | always say "I'm a development release" and it would be safe to bump the |
334 | reported minor version as soon as a release ships, which would aid perl |
335 | developers. |
336 | |
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337 | This task is really about thinking of an elegant way to arrange the C source |
338 | such that it's trivial for the Pumpking to flag "this is an official release" |
339 | when making a tarball, yet leave the default source saying "I'm not the |
340 | official release". |
341 | |
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342 | =head2 Tidy up global variables |
343 | |
344 | There's a note in F<intrpvar.h> |
345 | |
346 | /* These two variables are needed to preserve 5.8.x bincompat because |
347 | we can't change function prototypes of two exported functions. |
348 | Probably should be taken out of blead soon, and relevant prototypes |
349 | changed. */ |
350 | |
351 | So doing this, and removing any of the unused variables still present would |
352 | be good. |
353 | |
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354 | =head2 Ordering of "global" variables. |
355 | |
356 | F<thrdvar.h> and F<intrpvarh> define the "global" variables that need to be |
357 | per-thread under ithreads, where the variables are actually elements in a |
358 | structure. As C dictates, the variables must be laid out in order of |
359 | declaration. There is a comment |
360 | C</* Important ones in the first cache line (if alignment is done right) */> |
361 | which implies that at some point in the past the ordering was carefully chosen |
362 | (at least in part). However, it's clear that the ordering is less than perfect, |
363 | as currently there are things such as 7 C<bool>s in a row, then something |
364 | typically requiring 4 byte alignment, and then an odd C<bool> later on. |
365 | (C<bool>s are typically defined as C<char>s). So it would be good for someone |
366 | to review the ordering of the variables, to see how much alignment padding can |
367 | be removed. |
368 | |
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369 | =head2 bincompat functions |
370 | |
371 | There are lots of functions which are retained for binary compatibility. |
372 | Clean these up. Move them to mathom.c, and don't compile for blead? |
373 | |
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374 | =head2 am I hot or not? |
375 | |
376 | The idea of F<pp_hot.c> is that it contains the I<hot> ops, the ops that are |
377 | most commonly used. The idea is that by grouping them, their object code will |
378 | be adjacent in the executable, so they have a greater chance of already being |
379 | in the CPU cache (or swapped in) due to being near another op already in use. |
380 | |
381 | Except that it's not clear if these really are the most commonly used ops. So |
382 | anyone feeling like exercising their skill with coverage and profiling tools |
383 | might want to determine what ops I<really> are the most commonly used. And in |
384 | turn suggest evictions and promotions to achieve a better F<pp_hot.c>. |
385 | |
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386 | =head2 emulate the per-thread memory pool on Unix |
387 | |
388 | For Windows, ithreads allocates memory for each thread from a separate pool, |
389 | which it discards at thread exit. It also checks that memory is free()d to |
390 | the correct pool. Neither check is done on Unix, so code developed there won't |
391 | be subject to such strictures, so can harbour bugs that only show up when the |
392 | code reaches Windows. |
393 | |
394 | It would be good to be able to optionally emulate the Window pool system on |
395 | Unix, to let developers who only have access to Unix, or want to use |
396 | Unix-specific debugging tools, check for these problems. To do this would |
397 | involve figuring out how the C<PerlMem_*> macros wrap C<malloc()> access, and |
398 | providing a layer that records/checks the identity of the thread making the |
399 | call, and recording all the memory allocated by each thread via this API so |
400 | that it can be summarily free()d at thread exit. One implementation idea |
401 | would be to increase the size of allocation, and store the C<my_perl> pointer |
402 | (to identify the thread) at the start, along with pointers to make a linked |
403 | list of blocks for this thread. To avoid alignment problems it would be |
404 | necessary to do something like |
405 | |
406 | union memory_header_padded { |
407 | struct memory_header { |
408 | void *thread_id; /* For my_perl */ |
409 | void *next; /* Pointer to next block for this thread */ |
410 | } data; |
411 | long double padding; /* whatever type has maximal alignment constraint */ |
412 | }; |
413 | |
414 | |
415 | although C<long double> might not be the only type to add to the padding |
416 | union. |
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417 | |
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418 | =head2 reduce duplication in sv_setsv_flags |
419 | |
420 | C<Perl_sv_setsv_flags> has a comment |
421 | C</* There's a lot of redundancy below but we're going for speed here */> |
422 | |
423 | Whilst this was true 10 years ago, the growing disparity between RAM and CPU |
424 | speeds mean that the trade offs have changed. In addition, the duplicate code |
425 | adds to the maintenance burden. It would be good to see how much of the |
426 | redundancy can be pruned, particular in the less common paths. (Profiling |
427 | tools at the ready...). For example, why does the test for |
428 | "Can't redefine active sort subroutine" need to occur in two places? |
429 | |
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430 | |
431 | |
432 | |
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433 | =head1 Tasks that need a knowledge of XS |
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434 | |
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435 | These tasks would need C knowledge, and roughly the level of knowledge of |
436 | the perl API that comes from writing modules that use XS to interface to |
437 | C. |
438 | |
439 | =head2 IPv6 |
440 | |
441 | Clean this up. Check everything in core works |
442 | |
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443 | =head2 shrink C<GV>s, C<CV>s |
444 | |
445 | By removing unused elements and careful re-ordering, the structures for C<AV>s |
446 | and C<HV>s have recently been shrunk considerably. It's probable that the same |
447 | approach would find savings in C<GV>s and C<CV>s, if not all the other |
448 | larger-than-C<PVMG> types. |
449 | |
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450 | =head2 merge Perl_sv_2[inpu]v |
451 | |
452 | There's a lot of code shared between C<Perl_sv_2iv_flags>, |
453 | C<Perl_sv_2uv_flags>, C<Perl_sv_2nv>, and C<Perl_sv_2pv_flags>. It would be |
454 | interesting to see if some of it can be merged into common shared static |
455 | functions. In particular, C<Perl_sv_2uv_flags> started out as a cut&paste |
456 | from C<Perl_sv_2iv_flags> around 5.005_50 time, and it may be possible to |
457 | replace both with a single function that returns a value or union which is |
458 | split out by the macros in F<sv.h> |
459 | |
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460 | =head2 UTF8 caching code |
461 | |
462 | The string position/offset cache is not optional. It should be. |
463 | |
464 | =head2 Implicit Latin 1 => Unicode translation |
465 | |
466 | Conversions from byte strings to UTF-8 currently map high bit characters |
467 | to Unicode without translation (or, depending on how you look at it, by |
468 | implicitly assuming that the byte strings are in Latin-1). As perl assumes |
469 | the C locale by default, upgrading a string to UTF-8 may change the |
470 | meaning of its contents regarding character classes, case mapping, etc. |
471 | This should probably emit a warning (at least). |
472 | |
473 | This task is incremental - even a little bit of work on it will help. |
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474 | |
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475 | =head2 autovivification |
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476 | |
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477 | Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict; |
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478 | |
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479 | This task is incremental - even a little bit of work on it will help. |
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480 | |
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481 | =head2 Unicode in Filenames |
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482 | |
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483 | chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open, |
484 | opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen, |
485 | system, truncate, unlink, utime, -X. All these could potentially accept |
486 | Unicode filenames either as input or output (and in the case of system |
487 | and qx Unicode in general, as input or output to/from the shell). |
488 | Whether a filesystem - an operating system pair understands Unicode in |
489 | filenames varies. |
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490 | |
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491 | Known combinations that have some level of understanding include |
492 | Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac |
493 | OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to |
494 | create Unicode filenames, what forms of Unicode are accepted and used |
495 | (UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used, |
496 | and so on, varies. Finding the right level of interfacing to Perl |
497 | requires some thought. Remember that an OS does not implicate a |
498 | filesystem. |
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499 | |
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500 | (The Windows -C command flag "wide API support" has been at least |
501 | temporarily retired in 5.8.1, and the -C has been repurposed, see |
502 | L<perlrun>.) |
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503 | |
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504 | =head2 Unicode in %ENV |
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505 | |
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506 | Currently the %ENV entries are always byte strings. |
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507 | |
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508 | =head2 use less 'memory' |
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509 | |
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510 | Investigate trade offs to switch out perl's choices on memory usage. |
511 | Particularly perl should be able to give memory back. |
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512 | |
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513 | This task is incremental - even a little bit of work on it will help. |
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514 | |
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515 | =head2 Re-implement C<:unique> in a way that is actually thread-safe |
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516 | |
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517 | The old implementation made bad assumptions on several levels. A good 90% |
518 | solution might be just to make C<:unique> work to share the string buffer |
519 | of SvPVs. That way large constant strings can be shared between ithreads, |
520 | such as the configuration information in F<Config>. |
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521 | |
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522 | =head2 Make tainting consistent |
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523 | |
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524 | Tainting would be easier to use if it didn't take documented shortcuts and |
525 | allow taint to "leak" everywhere within an expression. |
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526 | |
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527 | =head2 readpipe(LIST) |
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528 | |
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529 | system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid |
530 | running a shell. readpipe() (the function behind qx//) could be similarly |
531 | extended. |
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532 | |
e50bb9a1 |
533 | |
e50bb9a1 |
534 | |
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535 | |
f86a8bc5 |
536 | |
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537 | =head1 Tasks that need a knowledge of the interpreter |
3298bd4d |
538 | |
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539 | These tasks would need C knowledge, and knowledge of how the interpreter works, |
540 | or a willingness to learn. |
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541 | |
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542 | =head2 lexical pragmas |
543 | |
544 | Reimplement the mechanism of lexical pragmas to be more extensible. Fix |
545 | current pragmas that don't work well (or at all) with lexical scopes or in |
546 | run-time eval(STRING) (C<sort>, C<re>, C<encoding> for example). MJD has a |
547 | preliminary patch that implements this. |
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548 | |
d10fc472 |
549 | =head2 Attach/detach debugger from running program |
1626a787 |
550 | |
cd793d32 |
551 | The old perltodo notes "With C<gdb>, you can attach the debugger to a running |
552 | program if you pass the process ID. It would be good to do this with the Perl |
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553 | debugger on a running Perl program, although I'm not sure how it would be |
554 | done." ssh and screen do this with named pipes in /tmp. Maybe we can too. |
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555 | |
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556 | =head2 inlining autoloaded constants |
d10fc472 |
557 | |
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558 | Currently the optimiser can inline constants when expressed as subroutines |
559 | with prototype ($) that return a constant. Likewise, many packages wrapping |
560 | C libraries export lots of constants as subroutines which are AUTOLOADed on |
561 | demand. However, these have no prototypes, so can't be seen as constants by |
562 | the optimiser. Some way of cheaply (low syntax, low memory overhead) to the |
563 | perl compiler that a name is a constant would be great, so that it knows to |
564 | call the AUTOLOAD routine at compile time, and then inline the constant. |
80b46460 |
565 | |
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566 | =head2 Constant folding |
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567 | |
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568 | The peephole optimiser should trap errors during constant folding, and give |
569 | up on the folding, rather than bailing out at compile time. It is quite |
570 | possible that the unfoldable constant is in unreachable code, eg something |
571 | akin to C<$a = 0/0 if 0;> |
572 | |
573 | =head2 LVALUE functions for lists |
574 | |
575 | The old perltodo notes that lvalue functions don't work for list or hash |
576 | slices. This would be good to fix. |
577 | |
578 | =head2 LVALUE functions in the debugger |
579 | |
580 | The old perltodo notes that lvalue functions don't work in the debugger. This |
581 | would be good to fix. |
582 | |
583 | =head2 _ prototype character |
584 | |
585 | Study the possibility of adding a new prototype character, C<_>, meaning |
586 | "this argument defaults to $_". |
587 | |
4e577f8b |
588 | =head2 state variables |
589 | |
590 | C<my $foo if 0;> is deprecated, and should be replaced with |
591 | C<state $x = "initial value\n";> the syntax from Perl 6. |
592 | |
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593 | =head2 @INC source filter to Filter::Simple |
594 | |
595 | The second return value from a sub in @INC can be a source filter. This isn't |
596 | documented. It should be changed to use Filter::Simple, tested and documented. |
597 | |
598 | =head2 regexp optimiser optional |
599 | |
600 | The regexp optimiser is not optional. It should configurable to be, to allow |
601 | its performance to be measured, and its bugs to be easily demonstrated. |
602 | |
603 | =head2 UNITCHECK |
604 | |
605 | Introduce a new special block, UNITCHECK, which is run at the end of a |
606 | compilation unit (module, file, eval(STRING) block). This will correspond to |
607 | the Perl 6 CHECK. Perl 5's CHECK cannot be changed or removed because the |
608 | O.pm/B.pm backend framework depends on it. |
609 | |
610 | =head2 optional optimizer |
611 | |
612 | Make the peephole optimizer optional. Currently it performs two tasks as |
613 | it walks the optree - genuine peephole optimisations, and necessary fixups of |
614 | ops. It would be good to find an efficient way to switch out the |
615 | optimisations whilst keeping the fixups. |
616 | |
617 | =head2 You WANT *how* many |
618 | |
619 | Currently contexts are void, scalar and list. split has a special mechanism in |
620 | place to pass in the number of return values wanted. It would be useful to |
621 | have a general mechanism for this, backwards compatible and little speed hit. |
622 | This would allow proposals such as short circuiting sort to be implemented |
623 | as a module on CPAN. |
624 | |
625 | =head2 lexical aliases |
626 | |
627 | Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>. |
628 | |
629 | =head2 entersub XS vs Perl |
630 | |
631 | At the moment pp_entersub is huge, and has code to deal with entering both |
632 | perl and XS subroutines. Subroutine implementations rarely change between |
633 | perl and XS at run time, so investigate using 2 ops to enter subs (one for |
634 | XS, one for perl) and swap between if a sub is redefined. |
2810d901 |
635 | |
636 | =head2 Self ties |
637 | |
638 | self ties are currently illegal because they caused too many segfaults. Maybe |
639 | the causes of these could be tracked down and self-ties on all types re- |
640 | instated. |
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641 | |
642 | =head2 Optimize away @_ |
643 | |
644 | The old perltodo notes "Look at the "reification" code in C<av.c>". |
645 | |
646 | =head2 switch ops |
647 | |
648 | The old perltodo notes "Although we have C<Switch.pm> in core, Larry points to |
649 | the dormant C<nswitch> and C<cswitch> ops in F<pp.c>; using these opcodes would |
650 | be much faster." |
651 | |
652 | =head2 What hooks would assertions need? |
653 | |
654 | Assertions are in the core, and work. However, assertions needed to be added |
655 | as a core patch, rather than an XS module in ext, or a CPAN module, because |
656 | the core has no hooks in the necessary places. It would be useful to |
657 | investigate what hooks would need to be added to make it possible to provide |
658 | the full assertion support from a CPAN module, so that we aren't constraining |
659 | the imagination of future CPAN authors. |
660 | |
661 | |
662 | |
663 | |
664 | |
665 | |
666 | |
667 | =head1 Big projects |
668 | |
669 | Tasks that will get your name mentioned in the description of the "Highlights |
670 | of 5.10" |
671 | |
672 | =head2 make ithreads more robust |
673 | |
4e577f8b |
674 | Generally make ithreads more robust. See also L</iCOW> |
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675 | |
676 | This task is incremental - even a little bit of work on it will help, and |
677 | will be greatly appreciated. |
678 | |
679 | =head2 iCOW |
680 | |
681 | Sarathy and Arthur have a proposal for an improved Copy On Write which |
682 | specifically will be able to COW new ithreads. If this can be implemented |
683 | it would be a good thing. |
684 | |
685 | =head2 (?{...}) closures in regexps |
686 | |
687 | Fix (or rewrite) the implementation of the C</(?{...})/> closures. |
688 | |
689 | =head2 A re-entrant regexp engine |
690 | |
691 | This will allow the use of a regex from inside (?{ }), (??{ }) and |
692 | (?(?{ })|) constructs. |