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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 | The addition of C<Pod::Simple> and its related modules may make this task |
81 | easier to complete. |
82 | |
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83 | =head2 Parallel testing |
84 | |
85 | The core regression test suite is getting ever more comprehensive, which has |
86 | the side effect that it takes longer to run. This isn't so good. Investigate |
87 | whether it would be feasible to give the harness script the B<option> of |
88 | running sets of tests in parallel. This would be useful for tests in |
89 | F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>. |
90 | |
91 | Questions to answer |
92 | |
93 | =over 4 |
94 | |
95 | =item 1 |
96 | |
97 | How does screen layout work when you're running more than one test? |
98 | |
99 | =item 2 |
100 | |
101 | How does the caller of test specify how many tests to run in parallel? |
102 | |
103 | =item 3 |
104 | |
105 | How do setup/teardown tests identify themselves? |
106 | |
107 | =back |
108 | |
109 | Pugs already does parallel testing - can their approach be re-used? |
110 | |
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111 | =head2 Make Schwern poorer |
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112 | |
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113 | We should have for everything. When all the core's modules are tested, |
114 | Schwern has promised to donate to $500 to TPF. We may need volunteers to |
115 | hold him upside down and shake vigorously in order to actually extract the |
116 | cash. |
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117 | |
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118 | See F<t/lib/1_compile.t> for the 3 remaining modules that need tests. |
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119 | |
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120 | =head2 Improve the coverage of the core tests |
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121 | |
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122 | Use Devel::Cover to ascertain the core's test coverage, then add tests that |
123 | are currently missing. |
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124 | |
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125 | =head2 test B |
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126 | |
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127 | A full test suite for the B module would be nice. |
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128 | |
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129 | =head2 A decent benchmark |
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130 | |
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131 | C<perlbench> seems impervious to any recent changes made to the perl core. It |
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132 | would be useful to have a reasonable general benchmarking suite that roughly |
133 | represented what current perl programs do, and measurably reported whether |
134 | tweaks to the core improve, degrade or don't really affect performance, to |
135 | guide people attempting to optimise the guts of perl. Gisle would welcome |
136 | new tests for perlbench. |
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137 | |
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138 | =head2 fix tainting bugs |
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139 | |
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140 | Fix the bugs revealed by running the test suite with the C<-t> switch (via |
141 | C<make test.taintwarn>). |
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142 | |
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143 | =head2 Dual life everything |
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144 | |
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145 | As part of the "dists" plan, anything that doesn't belong in the smallest perl |
146 | distribution needs to be dual lifed. Anything else can be too. Figure out what |
147 | changes would be needed to package that module and its tests up for CPAN, and |
148 | do so. Test it with older perl releases, and fix the problems you find. |
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149 | |
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150 | =head2 Improving C<threads::shared> |
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151 | |
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152 | Investigate whether C<threads::shared> could share aggregates properly with |
153 | only Perl level changes to shared.pm |
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154 | |
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155 | =head2 POSIX memory footprint |
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156 | |
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157 | Ilya observed that use POSIX; eats memory like there's no tomorrow, and at |
158 | various times worked to cut it down. There is probably still fat to cut out - |
159 | for example POSIX passes Exporter some very memory hungry data structures. |
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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 | |
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165 | |
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166 | |
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167 | =head1 Tasks that need a little sysadmin-type knowledge |
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168 | |
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169 | Or if you prefer, tasks that you would learn from, and broaden your skills |
170 | base... |
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171 | |
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172 | =head2 Relocatable perl |
173 | |
174 | The C level patches needed to create a relocatable perl binary are done, as |
175 | is the work on F<Config.pm>. All that's left to do is the C<Configure> tweaking |
176 | to let people specify how they want to do the install. |
177 | |
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178 | =head2 make HTML install work |
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179 | |
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180 | There is an C<installhtml> target in the Makefile. It's marked as |
181 | "experimental". It would be good to get this tested, make it work reliably, and |
182 | remove the "experimental" tag. This would include |
183 | |
184 | =over 4 |
185 | |
186 | =item 1 |
187 | |
188 | Checking that cross linking between various parts of the documentation works. |
189 | In particular that links work between the modules (files with POD in F<lib/>) |
190 | and the core documentation (files in F<pod/>) |
191 | |
192 | =item 2 |
193 | |
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194 | Work out how to split C<perlfunc> into chunks, preferably one per function |
195 | group, preferably with general case code that could be used elsewhere. |
196 | Challenges here are correctly identifying the groups of functions that go |
197 | together, and making the right named external cross-links point to the right |
198 | page. Things to be aware of are C<-X>, groups such as C<getpwnam> to |
199 | C<endservent>, two or more C<=items> giving the different parameter lists, such |
200 | as |
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201 | |
202 | =item substr EXPR,OFFSET,LENGTH,REPLACEMENT |
203 | |
204 | =item substr EXPR,OFFSET,LENGTH |
205 | |
206 | =item substr EXPR,OFFSET |
207 | |
208 | and different parameter lists having different meanings. (eg C<select>) |
209 | |
210 | =back |
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211 | |
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212 | =head2 compressed man pages |
213 | |
214 | Be able to install them. This would probably need a configure test to see how |
215 | the system does compressed man pages (same directory/different directory? |
216 | same filename/different filename), as well as tweaking the F<installman> script |
217 | to compress as necessary. |
218 | |
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219 | =head2 Add a code coverage target to the Makefile |
220 | |
221 | Make it easy for anyone to run Devel::Cover on the core's tests. The steps |
222 | to do this manually are roughly |
223 | |
224 | =over 4 |
225 | |
226 | =item * |
227 | |
228 | do a normal C<Configure>, but include Devel::Cover as a module to install |
229 | (see F<INSTALL> for how to do this) |
230 | |
231 | =item * |
232 | |
233 | make perl |
234 | |
235 | =item * |
236 | |
237 | cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness |
238 | |
239 | =item * |
240 | |
241 | Process the resulting Devel::Cover database |
242 | |
243 | =back |
244 | |
245 | This just give you the coverage of the F<.pm>s. To also get the C level |
246 | coverage you need to |
247 | |
248 | =over 4 |
249 | |
250 | =item * |
251 | |
252 | Additionally tell C<Configure> to use the appropriate C compiler flags for |
253 | C<gcov> |
254 | |
255 | =item * |
256 | |
257 | make perl.gcov |
258 | |
259 | (instead of C<make perl>) |
260 | |
261 | =item * |
262 | |
263 | After running the tests run C<gcov> to generate all the F<.gcov> files. |
264 | (Including down in the subdirectories of F<ext/> |
265 | |
266 | =item * |
267 | |
268 | (From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files |
269 | to get their stats into the cover_db directory. |
270 | |
271 | =item * |
272 | |
273 | Then process the Devel::Cover database |
274 | |
275 | =back |
276 | |
277 | It would be good to add a single switch to C<Configure> to specify that you |
278 | wanted to perform perl level coverage, and another to specify C level |
279 | coverage, and have C<Configure> and the F<Makefile> do all the right things |
280 | automatically. |
281 | |
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282 | =head2 Make Config.pm cope with differences between build and installed perl |
283 | |
284 | Quite often vendors ship a perl binary compiled with their (pay-for) |
285 | compilers. People install a free compiler, such as gcc. To work out how to |
286 | build extensions, Perl interrogates C<%Config>, so in this situation |
287 | C<%Config> describes compilers that aren't there, and extension building |
288 | fails. This forces people into choosing between re-compiling perl themselves |
289 | using the compiler they have, or only using modules that the vendor ships. |
290 | |
291 | It would be good to find a way teach C<Config.pm> about the installation setup, |
292 | possibly involving probing at install time or later, so that the C<%Config> in |
293 | a binary distribution better describes the installed machine, when the |
294 | installed machine differs from the build machine in some significant way. |
295 | |
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296 | =head2 make parallel builds work |
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297 | |
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298 | Currently parallel builds (such as C<make -j3>) don't work reliably. We believe |
299 | that this is due to incomplete dependency specification in the F<Makefile>. |
300 | It would be good if someone were able to track down the causes of these |
301 | problems, so that parallel builds worked properly. |
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302 | |
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303 | =head2 linker specification files |
304 | |
305 | Some platforms mandate that you provide a list of a shared library's external |
306 | symbols to the linker, so the core already has the infrastructure in place to |
307 | do this for generating shared perl libraries. My understanding is that the |
308 | GNU toolchain can accept an optional linker specification file, and restrict |
309 | visibility just to symbols declared in that file. It would be good to extend |
310 | F<makedef.pl> to support this format, and to provide a means within |
311 | C<Configure> to enable it. This would allow Unix users to test that the |
312 | export list is correct, and to build a perl that does not pollute the global |
313 | namespace with private symbols. |
314 | |
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315 | |
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316 | |
317 | |
318 | =head1 Tasks that need a little C knowledge |
319 | |
320 | These tasks would need a little C knowledge, but don't need any specific |
321 | background or experience with XS, or how the Perl interpreter works |
322 | |
323 | =head2 Make it clear from -v if this is the exact official release |
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324 | |
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325 | Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that |
326 | usually defines one local patch, of the form "MAINT12345" or "RC1". The output |
327 | of perl -v doesn't report that a perl isn't an official release, and this |
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328 | information can get lost in bugs reports. Because of this, the minor version |
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329 | isn't bumped up until RC time, to minimise the possibility of versions of perl |
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330 | escaping that believe themselves to be newer than they actually are. |
331 | |
332 | It would be useful to find an elegant way to have the "this is an interim |
333 | maintenance release" or "this is a release candidate" in the terse -v output, |
334 | and have it so that it's easy for the pumpking to remove this just as the |
335 | release tarball is rolled up. This way the version pulled out of rsync would |
336 | always say "I'm a development release" and it would be safe to bump the |
337 | reported minor version as soon as a release ships, which would aid perl |
338 | developers. |
339 | |
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340 | This task is really about thinking of an elegant way to arrange the C source |
341 | such that it's trivial for the Pumpking to flag "this is an official release" |
342 | when making a tarball, yet leave the default source saying "I'm not the |
343 | official release". |
344 | |
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345 | =head2 Tidy up global variables |
346 | |
347 | There's a note in F<intrpvar.h> |
348 | |
349 | /* These two variables are needed to preserve 5.8.x bincompat because |
350 | we can't change function prototypes of two exported functions. |
351 | Probably should be taken out of blead soon, and relevant prototypes |
352 | changed. */ |
353 | |
354 | So doing this, and removing any of the unused variables still present would |
355 | be good. |
356 | |
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357 | =head2 Ordering of "global" variables. |
358 | |
359 | F<thrdvar.h> and F<intrpvarh> define the "global" variables that need to be |
360 | per-thread under ithreads, where the variables are actually elements in a |
361 | structure. As C dictates, the variables must be laid out in order of |
362 | declaration. There is a comment |
363 | C</* Important ones in the first cache line (if alignment is done right) */> |
364 | which implies that at some point in the past the ordering was carefully chosen |
365 | (at least in part). However, it's clear that the ordering is less than perfect, |
366 | as currently there are things such as 7 C<bool>s in a row, then something |
367 | typically requiring 4 byte alignment, and then an odd C<bool> later on. |
368 | (C<bool>s are typically defined as C<char>s). So it would be good for someone |
369 | to review the ordering of the variables, to see how much alignment padding can |
370 | be removed. |
371 | |
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372 | =head2 bincompat functions |
373 | |
374 | There are lots of functions which are retained for binary compatibility. |
375 | Clean these up. Move them to mathom.c, and don't compile for blead? |
376 | |
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377 | =head2 am I hot or not? |
378 | |
379 | The idea of F<pp_hot.c> is that it contains the I<hot> ops, the ops that are |
380 | most commonly used. The idea is that by grouping them, their object code will |
381 | be adjacent in the executable, so they have a greater chance of already being |
382 | in the CPU cache (or swapped in) due to being near another op already in use. |
383 | |
384 | Except that it's not clear if these really are the most commonly used ops. So |
385 | anyone feeling like exercising their skill with coverage and profiling tools |
386 | might want to determine what ops I<really> are the most commonly used. And in |
387 | turn suggest evictions and promotions to achieve a better F<pp_hot.c>. |
388 | |
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389 | =head2 emulate the per-thread memory pool on Unix |
390 | |
391 | For Windows, ithreads allocates memory for each thread from a separate pool, |
392 | which it discards at thread exit. It also checks that memory is free()d to |
393 | the correct pool. Neither check is done on Unix, so code developed there won't |
394 | be subject to such strictures, so can harbour bugs that only show up when the |
395 | code reaches Windows. |
396 | |
397 | It would be good to be able to optionally emulate the Window pool system on |
398 | Unix, to let developers who only have access to Unix, or want to use |
399 | Unix-specific debugging tools, check for these problems. To do this would |
400 | involve figuring out how the C<PerlMem_*> macros wrap C<malloc()> access, and |
401 | providing a layer that records/checks the identity of the thread making the |
402 | call, and recording all the memory allocated by each thread via this API so |
403 | that it can be summarily free()d at thread exit. One implementation idea |
404 | would be to increase the size of allocation, and store the C<my_perl> pointer |
405 | (to identify the thread) at the start, along with pointers to make a linked |
406 | list of blocks for this thread. To avoid alignment problems it would be |
407 | necessary to do something like |
408 | |
409 | union memory_header_padded { |
410 | struct memory_header { |
411 | void *thread_id; /* For my_perl */ |
412 | void *next; /* Pointer to next block for this thread */ |
413 | } data; |
414 | long double padding; /* whatever type has maximal alignment constraint */ |
415 | }; |
416 | |
417 | |
418 | although C<long double> might not be the only type to add to the padding |
419 | union. |
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420 | |
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421 | =head2 reduce duplication in sv_setsv_flags |
422 | |
423 | C<Perl_sv_setsv_flags> has a comment |
424 | C</* There's a lot of redundancy below but we're going for speed here */> |
425 | |
426 | Whilst this was true 10 years ago, the growing disparity between RAM and CPU |
427 | speeds mean that the trade offs have changed. In addition, the duplicate code |
428 | adds to the maintenance burden. It would be good to see how much of the |
429 | redundancy can be pruned, particular in the less common paths. (Profiling |
430 | tools at the ready...). For example, why does the test for |
431 | "Can't redefine active sort subroutine" need to occur in two places? |
432 | |
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433 | |
434 | |
435 | |
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436 | =head1 Tasks that need a knowledge of XS |
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437 | |
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438 | These tasks would need C knowledge, and roughly the level of knowledge of |
439 | the perl API that comes from writing modules that use XS to interface to |
440 | C. |
441 | |
442 | =head2 IPv6 |
443 | |
444 | Clean this up. Check everything in core works |
445 | |
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446 | =head2 shrink C<GV>s, C<CV>s |
447 | |
448 | By removing unused elements and careful re-ordering, the structures for C<AV>s |
449 | and C<HV>s have recently been shrunk considerably. It's probable that the same |
450 | approach would find savings in C<GV>s and C<CV>s, if not all the other |
451 | larger-than-C<PVMG> types. |
452 | |
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453 | =head2 merge Perl_sv_2[inpu]v |
454 | |
455 | There's a lot of code shared between C<Perl_sv_2iv_flags>, |
456 | C<Perl_sv_2uv_flags>, C<Perl_sv_2nv>, and C<Perl_sv_2pv_flags>. It would be |
457 | interesting to see if some of it can be merged into common shared static |
458 | functions. In particular, C<Perl_sv_2uv_flags> started out as a cut&paste |
459 | from C<Perl_sv_2iv_flags> around 5.005_50 time, and it may be possible to |
460 | replace both with a single function that returns a value or union which is |
461 | split out by the macros in F<sv.h> |
462 | |
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463 | =head2 UTF8 caching code |
464 | |
465 | The string position/offset cache is not optional. It should be. |
466 | |
467 | =head2 Implicit Latin 1 => Unicode translation |
468 | |
469 | Conversions from byte strings to UTF-8 currently map high bit characters |
470 | to Unicode without translation (or, depending on how you look at it, by |
471 | implicitly assuming that the byte strings are in Latin-1). As perl assumes |
472 | the C locale by default, upgrading a string to UTF-8 may change the |
473 | meaning of its contents regarding character classes, case mapping, etc. |
474 | This should probably emit a warning (at least). |
475 | |
476 | This task is incremental - even a little bit of work on it will help. |
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477 | |
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478 | =head2 autovivification |
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479 | |
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480 | Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict; |
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481 | |
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482 | This task is incremental - even a little bit of work on it will help. |
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483 | |
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484 | =head2 Unicode in Filenames |
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485 | |
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486 | chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open, |
487 | opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen, |
488 | system, truncate, unlink, utime, -X. All these could potentially accept |
489 | Unicode filenames either as input or output (and in the case of system |
490 | and qx Unicode in general, as input or output to/from the shell). |
491 | Whether a filesystem - an operating system pair understands Unicode in |
492 | filenames varies. |
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493 | |
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494 | Known combinations that have some level of understanding include |
495 | Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac |
496 | OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to |
497 | create Unicode filenames, what forms of Unicode are accepted and used |
498 | (UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used, |
499 | and so on, varies. Finding the right level of interfacing to Perl |
500 | requires some thought. Remember that an OS does not implicate a |
501 | filesystem. |
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502 | |
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503 | (The Windows -C command flag "wide API support" has been at least |
504 | temporarily retired in 5.8.1, and the -C has been repurposed, see |
505 | L<perlrun>.) |
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506 | |
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507 | =head2 Unicode in %ENV |
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508 | |
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509 | Currently the %ENV entries are always byte strings. |
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510 | |
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511 | =head2 use less 'memory' |
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512 | |
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513 | Investigate trade offs to switch out perl's choices on memory usage. |
514 | Particularly perl should be able to give memory back. |
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515 | |
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516 | This task is incremental - even a little bit of work on it will help. |
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517 | |
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518 | =head2 Re-implement C<:unique> in a way that is actually thread-safe |
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519 | |
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520 | The old implementation made bad assumptions on several levels. A good 90% |
521 | solution might be just to make C<:unique> work to share the string buffer |
522 | of SvPVs. That way large constant strings can be shared between ithreads, |
523 | such as the configuration information in F<Config>. |
0abe3f7c |
524 | |
0bdfc961 |
525 | =head2 Make tainting consistent |
0abe3f7c |
526 | |
0bdfc961 |
527 | Tainting would be easier to use if it didn't take documented shortcuts and |
528 | allow taint to "leak" everywhere within an expression. |
0abe3f7c |
529 | |
0bdfc961 |
530 | =head2 readpipe(LIST) |
0abe3f7c |
531 | |
0bdfc961 |
532 | system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid |
533 | running a shell. readpipe() (the function behind qx//) could be similarly |
534 | extended. |
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535 | |
e50bb9a1 |
536 | |
e50bb9a1 |
537 | |
e50bb9a1 |
538 | |
f86a8bc5 |
539 | |
0bdfc961 |
540 | =head1 Tasks that need a knowledge of the interpreter |
3298bd4d |
541 | |
0bdfc961 |
542 | These tasks would need C knowledge, and knowledge of how the interpreter works, |
543 | or a willingness to learn. |
3298bd4d |
544 | |
0bdfc961 |
545 | =head2 lexical pragmas |
546 | |
547 | Reimplement the mechanism of lexical pragmas to be more extensible. Fix |
548 | current pragmas that don't work well (or at all) with lexical scopes or in |
549 | run-time eval(STRING) (C<sort>, C<re>, C<encoding> for example). MJD has a |
550 | preliminary patch that implements this. |
0562c0e3 |
551 | |
d10fc472 |
552 | =head2 Attach/detach debugger from running program |
1626a787 |
553 | |
cd793d32 |
554 | The old perltodo notes "With C<gdb>, you can attach the debugger to a running |
555 | program if you pass the process ID. It would be good to do this with the Perl |
0bdfc961 |
556 | debugger on a running Perl program, although I'm not sure how it would be |
557 | done." ssh and screen do this with named pipes in /tmp. Maybe we can too. |
1626a787 |
558 | |
0bdfc961 |
559 | =head2 Constant folding |
80b46460 |
560 | |
0bdfc961 |
561 | The peephole optimiser should trap errors during constant folding, and give |
562 | up on the folding, rather than bailing out at compile time. It is quite |
563 | possible that the unfoldable constant is in unreachable code, eg something |
564 | akin to C<$a = 0/0 if 0;> |
565 | |
566 | =head2 LVALUE functions for lists |
567 | |
568 | The old perltodo notes that lvalue functions don't work for list or hash |
569 | slices. This would be good to fix. |
570 | |
571 | =head2 LVALUE functions in the debugger |
572 | |
573 | The old perltodo notes that lvalue functions don't work in the debugger. This |
574 | would be good to fix. |
575 | |
576 | =head2 _ prototype character |
577 | |
578 | Study the possibility of adding a new prototype character, C<_>, meaning |
579 | "this argument defaults to $_". |
580 | |
4e577f8b |
581 | =head2 state variables |
582 | |
583 | C<my $foo if 0;> is deprecated, and should be replaced with |
584 | C<state $x = "initial value\n";> the syntax from Perl 6. |
585 | |
0bdfc961 |
586 | =head2 @INC source filter to Filter::Simple |
587 | |
588 | The second return value from a sub in @INC can be a source filter. This isn't |
589 | documented. It should be changed to use Filter::Simple, tested and documented. |
590 | |
591 | =head2 regexp optimiser optional |
592 | |
593 | The regexp optimiser is not optional. It should configurable to be, to allow |
594 | its performance to be measured, and its bugs to be easily demonstrated. |
595 | |
596 | =head2 UNITCHECK |
597 | |
598 | Introduce a new special block, UNITCHECK, which is run at the end of a |
599 | compilation unit (module, file, eval(STRING) block). This will correspond to |
600 | the Perl 6 CHECK. Perl 5's CHECK cannot be changed or removed because the |
601 | O.pm/B.pm backend framework depends on it. |
602 | |
603 | =head2 optional optimizer |
604 | |
605 | Make the peephole optimizer optional. Currently it performs two tasks as |
606 | it walks the optree - genuine peephole optimisations, and necessary fixups of |
607 | ops. It would be good to find an efficient way to switch out the |
608 | optimisations whilst keeping the fixups. |
609 | |
610 | =head2 You WANT *how* many |
611 | |
612 | Currently contexts are void, scalar and list. split has a special mechanism in |
613 | place to pass in the number of return values wanted. It would be useful to |
614 | have a general mechanism for this, backwards compatible and little speed hit. |
615 | This would allow proposals such as short circuiting sort to be implemented |
616 | as a module on CPAN. |
617 | |
618 | =head2 lexical aliases |
619 | |
620 | Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>. |
621 | |
622 | =head2 entersub XS vs Perl |
623 | |
624 | At the moment pp_entersub is huge, and has code to deal with entering both |
625 | perl and XS subroutines. Subroutine implementations rarely change between |
626 | perl and XS at run time, so investigate using 2 ops to enter subs (one for |
627 | XS, one for perl) and swap between if a sub is redefined. |
2810d901 |
628 | |
629 | =head2 Self ties |
630 | |
631 | self ties are currently illegal because they caused too many segfaults. Maybe |
632 | the causes of these could be tracked down and self-ties on all types re- |
633 | instated. |
0bdfc961 |
634 | |
635 | =head2 Optimize away @_ |
636 | |
637 | The old perltodo notes "Look at the "reification" code in C<av.c>". |
638 | |
0bdfc961 |
639 | =head2 What hooks would assertions need? |
640 | |
641 | Assertions are in the core, and work. However, assertions needed to be added |
642 | as a core patch, rather than an XS module in ext, or a CPAN module, because |
643 | the core has no hooks in the necessary places. It would be useful to |
644 | investigate what hooks would need to be added to make it possible to provide |
645 | the full assertion support from a CPAN module, so that we aren't constraining |
646 | the imagination of future CPAN authors. |
647 | |
648 | |
649 | |
650 | |
651 | |
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652 | =head1 Big projects |
653 | |
654 | Tasks that will get your name mentioned in the description of the "Highlights |
655 | of 5.10" |
656 | |
657 | =head2 make ithreads more robust |
658 | |
4e577f8b |
659 | Generally make ithreads more robust. See also L</iCOW> |
0bdfc961 |
660 | |
661 | This task is incremental - even a little bit of work on it will help, and |
662 | will be greatly appreciated. |
663 | |
664 | =head2 iCOW |
665 | |
666 | Sarathy and Arthur have a proposal for an improved Copy On Write which |
667 | specifically will be able to COW new ithreads. If this can be implemented |
668 | it would be a good thing. |
669 | |
670 | =head2 (?{...}) closures in regexps |
671 | |
672 | Fix (or rewrite) the implementation of the C</(?{...})/> closures. |
673 | |
674 | =head2 A re-entrant regexp engine |
675 | |
676 | This will allow the use of a regex from inside (?{ }), (??{ }) and |
677 | (?(?{ })|) constructs. |