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1 | =head1 NAME |
2 | ||
3 | perltodo - Perl TO-DO List | |
4 | ||
5 | =head1 DESCRIPTION | |
6 | ||
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. | |
11 | ||
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: | |
15 | ||
16 | http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/ | |
17 | ||
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? | |
22 | ||
23 | =head1 The roadmap to 5.10 | |
24 | ||
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 5.9.4 release | |
29 | ||
30 | =over | |
31 | ||
32 | =item * | |
33 | ||
34 | Review assertions. Review syntax to combine assertions. Assertions could take | |
35 | advantage of the lexical pragmas work. L</What hooks would assertions need?> | |
36 | ||
37 | =back | |
38 | ||
39 | =head2 Needed for a 5.9.5 release | |
40 | ||
41 | =over | |
42 | ||
43 | =item * | |
44 | Implement L</_ prototype character> | |
45 | ||
46 | =item * | |
47 | Implement L</state variables> | |
48 | ||
49 | =back | |
50 | ||
51 | =head2 Needed for a 5.9.6 release | |
52 | ||
53 | Stabilisation. If all goes well, this will be the equivalent of a 5.10-beta. | |
54 | ||
55 | =head1 Tasks that only need Perl knowledge | |
56 | ||
57 | =head2 common test code for timed bail out | |
58 | ||
59 | Write portable self destruct code for tests to stop them burning CPU in | |
60 | infinite loops. This needs to avoid using alarm, as some of the tests are | |
61 | testing alarm/sleep or timers. | |
62 | ||
63 | =head2 POD -> HTML conversion in the core still sucks | |
64 | ||
65 | Which is crazy given just how simple POD purports to be, and how simple HTML | |
66 | can be. It's not actually I<as> simple as it sounds, particularly with the | |
67 | flexibility POD allows for C<=item>, but it would be good to improve the | |
68 | visual appeal of the HTML generated, and to avoid it having any validation | |
69 | errors. See also L</make HTML install work>, as the layout of installation tree | |
70 | is needed to improve the cross-linking. | |
71 | ||
72 | The addition of C<Pod::Simple> and its related modules may make this task | |
73 | easier to complete. | |
74 | ||
75 | =head2 Parallel testing | |
76 | ||
77 | The core regression test suite is getting ever more comprehensive, which has | |
78 | the side effect that it takes longer to run. This isn't so good. Investigate | |
79 | whether it would be feasible to give the harness script the B<option> of | |
80 | running sets of tests in parallel. This would be useful for tests in | |
81 | F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>. | |
82 | ||
83 | Questions to answer | |
84 | ||
85 | =over 4 | |
86 | ||
87 | =item 1 | |
88 | ||
89 | How does screen layout work when you're running more than one test? | |
90 | ||
91 | =item 2 | |
92 | ||
93 | How does the caller of test specify how many tests to run in parallel? | |
94 | ||
95 | =item 3 | |
96 | ||
97 | How do setup/teardown tests identify themselves? | |
98 | ||
99 | =back | |
100 | ||
101 | Pugs already does parallel testing - can their approach be re-used? | |
102 | ||
103 | =head2 Make Schwern poorer | |
104 | ||
105 | We should have for everything. When all the core's modules are tested, | |
106 | Schwern has promised to donate to $500 to TPF. We may need volunteers to | |
107 | hold him upside down and shake vigorously in order to actually extract the | |
108 | cash. | |
109 | ||
110 | See F<t/lib/1_compile.t> for the 3 remaining modules that need tests. | |
111 | ||
112 | =head2 Improve the coverage of the core tests | |
113 | ||
114 | Use Devel::Cover to ascertain the core's test coverage, then add tests that | |
115 | are currently missing. | |
116 | ||
117 | =head2 test B | |
118 | ||
119 | A full test suite for the B module would be nice. | |
120 | ||
121 | =head2 A decent benchmark | |
122 | ||
123 | C<perlbench> seems impervious to any recent changes made to the perl core. It | |
124 | would be useful to have a reasonable general benchmarking suite that roughly | |
125 | represented what current perl programs do, and measurably reported whether | |
126 | tweaks to the core improve, degrade or don't really affect performance, to | |
127 | guide people attempting to optimise the guts of perl. Gisle would welcome | |
128 | new tests for perlbench. | |
129 | ||
130 | =head2 fix tainting bugs | |
131 | ||
132 | Fix the bugs revealed by running the test suite with the C<-t> switch (via | |
133 | C<make test.taintwarn>). | |
134 | ||
135 | =head2 Dual life everything | |
136 | ||
137 | As part of the "dists" plan, anything that doesn't belong in the smallest perl | |
138 | distribution needs to be dual lifed. Anything else can be too. Figure out what | |
139 | changes would be needed to package that module and its tests up for CPAN, and | |
140 | do so. Test it with older perl releases, and fix the problems you find. | |
141 | ||
142 | =head2 Improving C<threads::shared> | |
143 | ||
144 | Investigate whether C<threads::shared> could share aggregates properly with | |
145 | only Perl level changes to shared.pm | |
146 | ||
147 | =head2 POSIX memory footprint | |
148 | ||
149 | Ilya observed that use POSIX; eats memory like there's no tomorrow, and at | |
150 | various times worked to cut it down. There is probably still fat to cut out - | |
151 | for example POSIX passes Exporter some very memory hungry data structures. | |
152 | ||
153 | ||
154 | ||
155 | ||
156 | ||
157 | ||
158 | ||
159 | =head1 Tasks that need a little sysadmin-type knowledge | |
160 | ||
161 | Or if you prefer, tasks that you would learn from, and broaden your skills | |
162 | base... | |
163 | ||
164 | =head2 Relocatable perl | |
165 | ||
166 | The C level patches needed to create a relocatable perl binary are done, as | |
167 | is the work on F<Config.pm>. All that's left to do is the C<Configure> tweaking | |
168 | to let people specify how they want to do the install. | |
169 | ||
170 | =head2 make HTML install work | |
171 | ||
172 | There is an C<installhtml> target in the Makefile. It's marked as | |
173 | "experimental". It would be good to get this tested, make it work reliably, and | |
174 | remove the "experimental" tag. This would include | |
175 | ||
176 | =over 4 | |
177 | ||
178 | =item 1 | |
179 | ||
180 | Checking that cross linking between various parts of the documentation works. | |
181 | In particular that links work between the modules (files with POD in F<lib/>) | |
182 | and the core documentation (files in F<pod/>) | |
183 | ||
184 | =item 2 | |
185 | ||
186 | Work out how to split C<perlfunc> into chunks, preferably one per function | |
187 | group, preferably with general case code that could be used elsewhere. | |
188 | Challenges here are correctly identifying the groups of functions that go | |
189 | together, and making the right named external cross-links point to the right | |
190 | page. Things to be aware of are C<-X>, groups such as C<getpwnam> to | |
191 | C<endservent>, two or more C<=items> giving the different parameter lists, such | |
192 | as | |
193 | ||
194 | =item substr EXPR,OFFSET,LENGTH,REPLACEMENT | |
195 | ||
196 | =item substr EXPR,OFFSET,LENGTH | |
197 | ||
198 | =item substr EXPR,OFFSET | |
199 | ||
200 | and different parameter lists having different meanings. (eg C<select>) | |
201 | ||
202 | =back | |
203 | ||
204 | =head2 compressed man pages | |
205 | ||
206 | Be able to install them. This would probably need a configure test to see how | |
207 | the system does compressed man pages (same directory/different directory? | |
208 | same filename/different filename), as well as tweaking the F<installman> script | |
209 | to compress as necessary. | |
210 | ||
211 | =head2 Add a code coverage target to the Makefile | |
212 | ||
213 | Make it easy for anyone to run Devel::Cover on the core's tests. The steps | |
214 | to do this manually are roughly | |
215 | ||
216 | =over 4 | |
217 | ||
218 | =item * | |
219 | ||
220 | do a normal C<Configure>, but include Devel::Cover as a module to install | |
221 | (see F<INSTALL> for how to do this) | |
222 | ||
223 | =item * | |
224 | ||
225 | make perl | |
226 | ||
227 | =item * | |
228 | ||
229 | cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness | |
230 | ||
231 | =item * | |
232 | ||
233 | Process the resulting Devel::Cover database | |
234 | ||
235 | =back | |
236 | ||
237 | This just give you the coverage of the F<.pm>s. To also get the C level | |
238 | coverage you need to | |
239 | ||
240 | =over 4 | |
241 | ||
242 | =item * | |
243 | ||
244 | Additionally tell C<Configure> to use the appropriate C compiler flags for | |
245 | C<gcov> | |
246 | ||
247 | =item * | |
248 | ||
249 | make perl.gcov | |
250 | ||
251 | (instead of C<make perl>) | |
252 | ||
253 | =item * | |
254 | ||
255 | After running the tests run C<gcov> to generate all the F<.gcov> files. | |
256 | (Including down in the subdirectories of F<ext/> | |
257 | ||
258 | =item * | |
259 | ||
260 | (From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files | |
261 | to get their stats into the cover_db directory. | |
262 | ||
263 | =item * | |
264 | ||
265 | Then process the Devel::Cover database | |
266 | ||
267 | =back | |
268 | ||
269 | It would be good to add a single switch to C<Configure> to specify that you | |
270 | wanted to perform perl level coverage, and another to specify C level | |
271 | coverage, and have C<Configure> and the F<Makefile> do all the right things | |
272 | automatically. | |
273 | ||
274 | =head2 Make Config.pm cope with differences between build and installed perl | |
275 | ||
276 | Quite often vendors ship a perl binary compiled with their (pay-for) | |
277 | compilers. People install a free compiler, such as gcc. To work out how to | |
278 | build extensions, Perl interrogates C<%Config>, so in this situation | |
279 | C<%Config> describes compilers that aren't there, and extension building | |
280 | fails. This forces people into choosing between re-compiling perl themselves | |
281 | using the compiler they have, or only using modules that the vendor ships. | |
282 | ||
283 | It would be good to find a way teach C<Config.pm> about the installation setup, | |
284 | possibly involving probing at install time or later, so that the C<%Config> in | |
285 | a binary distribution better describes the installed machine, when the | |
286 | installed machine differs from the build machine in some significant way. | |
287 | ||
288 | =head2 make parallel builds work | |
289 | ||
290 | Currently parallel builds (such as C<make -j3>) don't work reliably. We believe | |
291 | that this is due to incomplete dependency specification in the F<Makefile>. | |
292 | It would be good if someone were able to track down the causes of these | |
293 | problems, so that parallel builds worked properly. | |
294 | ||
295 | =head2 linker specification files | |
296 | ||
297 | Some platforms mandate that you provide a list of a shared library's external | |
298 | symbols to the linker, so the core already has the infrastructure in place to | |
299 | do this for generating shared perl libraries. My understanding is that the | |
300 | GNU toolchain can accept an optional linker specification file, and restrict | |
301 | visibility just to symbols declared in that file. It would be good to extend | |
302 | F<makedef.pl> to support this format, and to provide a means within | |
303 | C<Configure> to enable it. This would allow Unix users to test that the | |
304 | export list is correct, and to build a perl that does not pollute the global | |
305 | namespace with private symbols. | |
306 | ||
307 | ||
308 | ||
309 | ||
310 | =head1 Tasks that need a little C knowledge | |
311 | ||
312 | These tasks would need a little C knowledge, but don't need any specific | |
313 | background or experience with XS, or how the Perl interpreter works | |
314 | ||
315 | =head2 Make it clear from -v if this is the exact official release | |
316 | ||
317 | Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that | |
318 | usually defines one local patch, of the form "MAINT12345" or "RC1". The output | |
319 | of perl -v doesn't report that a perl isn't an official release, and this | |
320 | information can get lost in bugs reports. Because of this, the minor version | |
321 | isn't bumped up until RC time, to minimise the possibility of versions of perl | |
322 | escaping that believe themselves to be newer than they actually are. | |
323 | ||
324 | It would be useful to find an elegant way to have the "this is an interim | |
325 | maintenance release" or "this is a release candidate" in the terse -v output, | |
326 | and have it so that it's easy for the pumpking to remove this just as the | |
327 | release tarball is rolled up. This way the version pulled out of rsync would | |
328 | always say "I'm a development release" and it would be safe to bump the | |
329 | reported minor version as soon as a release ships, which would aid perl | |
330 | developers. | |
331 | ||
332 | This task is really about thinking of an elegant way to arrange the C source | |
333 | such that it's trivial for the Pumpking to flag "this is an official release" | |
334 | when making a tarball, yet leave the default source saying "I'm not the | |
335 | official release". | |
336 | ||
337 | =head2 Tidy up global variables | |
338 | ||
339 | There's a note in F<intrpvar.h> | |
340 | ||
341 | /* These two variables are needed to preserve 5.8.x bincompat because | |
342 | we can't change function prototypes of two exported functions. | |
343 | Probably should be taken out of blead soon, and relevant prototypes | |
344 | changed. */ | |
345 | ||
346 | So doing this, and removing any of the unused variables still present would | |
347 | be good. | |
348 | ||
349 | =head2 Ordering of "global" variables. | |
350 | ||
351 | F<thrdvar.h> and F<intrpvarh> define the "global" variables that need to be | |
352 | per-thread under ithreads, where the variables are actually elements in a | |
353 | structure. As C dictates, the variables must be laid out in order of | |
354 | declaration. There is a comment | |
355 | C</* Important ones in the first cache line (if alignment is done right) */> | |
356 | which implies that at some point in the past the ordering was carefully chosen | |
357 | (at least in part). However, it's clear that the ordering is less than perfect, | |
358 | as currently there are things such as 7 C<bool>s in a row, then something | |
359 | typically requiring 4 byte alignment, and then an odd C<bool> later on. | |
360 | (C<bool>s are typically defined as C<char>s). So it would be good for someone | |
361 | to review the ordering of the variables, to see how much alignment padding can | |
362 | be removed. | |
363 | ||
364 | =head2 bincompat functions | |
365 | ||
366 | There are lots of functions which are retained for binary compatibility. | |
367 | Clean these up. Move them to mathom.c, and don't compile for blead? | |
368 | ||
369 | =head2 am I hot or not? | |
370 | ||
371 | The idea of F<pp_hot.c> is that it contains the I<hot> ops, the ops that are | |
372 | most commonly used. The idea is that by grouping them, their object code will | |
373 | be adjacent in the executable, so they have a greater chance of already being | |
374 | in the CPU cache (or swapped in) due to being near another op already in use. | |
375 | ||
376 | Except that it's not clear if these really are the most commonly used ops. So | |
377 | anyone feeling like exercising their skill with coverage and profiling tools | |
378 | might want to determine what ops I<really> are the most commonly used. And in | |
379 | turn suggest evictions and promotions to achieve a better F<pp_hot.c>. | |
380 | ||
381 | =head2 emulate the per-thread memory pool on Unix | |
382 | ||
383 | For Windows, ithreads allocates memory for each thread from a separate pool, | |
384 | which it discards at thread exit. It also checks that memory is free()d to | |
385 | the correct pool. Neither check is done on Unix, so code developed there won't | |
386 | be subject to such strictures, so can harbour bugs that only show up when the | |
387 | code reaches Windows. | |
388 | ||
389 | It would be good to be able to optionally emulate the Window pool system on | |
390 | Unix, to let developers who only have access to Unix, or want to use | |
391 | Unix-specific debugging tools, check for these problems. To do this would | |
392 | involve figuring out how the C<PerlMem_*> macros wrap C<malloc()> access, and | |
393 | providing a layer that records/checks the identity of the thread making the | |
394 | call, and recording all the memory allocated by each thread via this API so | |
395 | that it can be summarily free()d at thread exit. One implementation idea | |
396 | would be to increase the size of allocation, and store the C<my_perl> pointer | |
397 | (to identify the thread) at the start, along with pointers to make a linked | |
398 | list of blocks for this thread. To avoid alignment problems it would be | |
399 | necessary to do something like | |
400 | ||
401 | union memory_header_padded { | |
402 | struct memory_header { | |
403 | void *thread_id; /* For my_perl */ | |
404 | void *next; /* Pointer to next block for this thread */ | |
405 | } data; | |
406 | long double padding; /* whatever type has maximal alignment constraint */ | |
407 | }; | |
408 | ||
409 | ||
410 | although C<long double> might not be the only type to add to the padding | |
411 | union. | |
412 | ||
413 | =head2 reduce duplication in sv_setsv_flags | |
414 | ||
415 | C<Perl_sv_setsv_flags> has a comment | |
416 | C</* There's a lot of redundancy below but we're going for speed here */> | |
417 | ||
418 | Whilst this was true 10 years ago, the growing disparity between RAM and CPU | |
419 | speeds mean that the trade offs have changed. In addition, the duplicate code | |
420 | adds to the maintenance burden. It would be good to see how much of the | |
421 | redundancy can be pruned, particular in the less common paths. (Profiling | |
422 | tools at the ready...). For example, why does the test for | |
423 | "Can't redefine active sort subroutine" need to occur in two places? | |
424 | ||
425 | ||
426 | ||
427 | ||
428 | =head1 Tasks that need a knowledge of XS | |
429 | ||
430 | These tasks would need C knowledge, and roughly the level of knowledge of | |
431 | the perl API that comes from writing modules that use XS to interface to | |
432 | C. | |
433 | ||
434 | =head2 IPv6 | |
435 | ||
436 | Clean this up. Check everything in core works | |
437 | ||
438 | =head2 shrink C<GV>s, C<CV>s | |
439 | ||
440 | By removing unused elements and careful re-ordering, the structures for C<AV>s | |
441 | and C<HV>s have recently been shrunk considerably. It's probable that the same | |
442 | approach would find savings in C<GV>s and C<CV>s, if not all the other | |
443 | larger-than-C<PVMG> types. | |
444 | ||
445 | =head2 merge Perl_sv_2[inpu]v | |
446 | ||
447 | There's a lot of code shared between C<Perl_sv_2iv_flags>, | |
448 | C<Perl_sv_2uv_flags>, C<Perl_sv_2nv>, and C<Perl_sv_2pv_flags>. It would be | |
449 | interesting to see if some of it can be merged into common shared static | |
450 | functions. In particular, C<Perl_sv_2uv_flags> started out as a cut&paste | |
451 | from C<Perl_sv_2iv_flags> around 5.005_50 time, and it may be possible to | |
452 | replace both with a single function that returns a value or union which is | |
453 | split out by the macros in F<sv.h> | |
454 | ||
455 | =head2 UTF8 caching code | |
456 | ||
457 | The string position/offset cache is not optional. It should be. | |
458 | ||
459 | =head2 Implicit Latin 1 => Unicode translation | |
460 | ||
461 | Conversions from byte strings to UTF-8 currently map high bit characters | |
462 | to Unicode without translation (or, depending on how you look at it, by | |
463 | implicitly assuming that the byte strings are in Latin-1). As perl assumes | |
464 | the C locale by default, upgrading a string to UTF-8 may change the | |
465 | meaning of its contents regarding character classes, case mapping, etc. | |
466 | This should probably emit a warning (at least). | |
467 | ||
468 | This task is incremental - even a little bit of work on it will help. | |
469 | ||
470 | =head2 autovivification | |
471 | ||
472 | Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict; | |
473 | ||
474 | This task is incremental - even a little bit of work on it will help. | |
475 | ||
476 | =head2 Unicode in Filenames | |
477 | ||
478 | chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open, | |
479 | opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen, | |
480 | system, truncate, unlink, utime, -X. All these could potentially accept | |
481 | Unicode filenames either as input or output (and in the case of system | |
482 | and qx Unicode in general, as input or output to/from the shell). | |
483 | Whether a filesystem - an operating system pair understands Unicode in | |
484 | filenames varies. | |
485 | ||
486 | Known combinations that have some level of understanding include | |
487 | Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac | |
488 | OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to | |
489 | create Unicode filenames, what forms of Unicode are accepted and used | |
490 | (UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used, | |
491 | and so on, varies. Finding the right level of interfacing to Perl | |
492 | requires some thought. Remember that an OS does not implicate a | |
493 | filesystem. | |
494 | ||
495 | (The Windows -C command flag "wide API support" has been at least | |
496 | temporarily retired in 5.8.1, and the -C has been repurposed, see | |
497 | L<perlrun>.) | |
498 | ||
499 | =head2 Unicode in %ENV | |
500 | ||
501 | Currently the %ENV entries are always byte strings. | |
502 | ||
503 | =head2 use less 'memory' | |
504 | ||
505 | Investigate trade offs to switch out perl's choices on memory usage. | |
506 | Particularly perl should be able to give memory back. | |
507 | ||
508 | This task is incremental - even a little bit of work on it will help. | |
509 | ||
510 | =head2 Re-implement C<:unique> in a way that is actually thread-safe | |
511 | ||
512 | The old implementation made bad assumptions on several levels. A good 90% | |
513 | solution might be just to make C<:unique> work to share the string buffer | |
514 | of SvPVs. That way large constant strings can be shared between ithreads, | |
515 | such as the configuration information in F<Config>. | |
516 | ||
517 | =head2 Make tainting consistent | |
518 | ||
519 | Tainting would be easier to use if it didn't take documented shortcuts and | |
520 | allow taint to "leak" everywhere within an expression. | |
521 | ||
522 | =head2 readpipe(LIST) | |
523 | ||
524 | system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid | |
525 | running a shell. readpipe() (the function behind qx//) could be similarly | |
526 | extended. | |
527 | ||
528 | ||
529 | ||
530 | ||
531 | ||
532 | =head1 Tasks that need a knowledge of the interpreter | |
533 | ||
534 | These tasks would need C knowledge, and knowledge of how the interpreter works, | |
535 | or a willingness to learn. | |
536 | ||
537 | =head2 lexical pragmas | |
538 | ||
539 | Document the new support for lexical pragmas in 5.9.3 and how %^H works. | |
540 | Maybe C<re>, C<encoding>, maybe other pragmas could be made lexical. | |
541 | ||
542 | =head2 Attach/detach debugger from running program | |
543 | ||
544 | The old perltodo notes "With C<gdb>, you can attach the debugger to a running | |
545 | program if you pass the process ID. It would be good to do this with the Perl | |
546 | debugger on a running Perl program, although I'm not sure how it would be | |
547 | done." ssh and screen do this with named pipes in /tmp. Maybe we can too. | |
548 | ||
549 | =head2 Constant folding | |
550 | ||
551 | The peephole optimiser should trap errors during constant folding, and give | |
552 | up on the folding, rather than bailing out at compile time. It is quite | |
553 | possible that the unfoldable constant is in unreachable code, eg something | |
554 | akin to C<$a = 0/0 if 0;> | |
555 | ||
556 | =head2 LVALUE functions for lists | |
557 | ||
558 | The old perltodo notes that lvalue functions don't work for list or hash | |
559 | slices. This would be good to fix. | |
560 | ||
561 | =head2 LVALUE functions in the debugger | |
562 | ||
563 | The old perltodo notes that lvalue functions don't work in the debugger. This | |
564 | would be good to fix. | |
565 | ||
566 | =head2 _ prototype character | |
567 | ||
568 | Study the possibility of adding a new prototype character, C<_>, meaning | |
569 | "this argument defaults to $_". | |
570 | ||
571 | =head2 state variables | |
572 | ||
573 | C<my $foo if 0;> is deprecated, and should be replaced with | |
574 | C<state $x = "initial value\n";> the syntax from Perl 6. | |
575 | ||
576 | =head2 @INC source filter to Filter::Simple | |
577 | ||
578 | The second return value from a sub in @INC can be a source filter. This isn't | |
579 | documented. It should be changed to use Filter::Simple, tested and documented. | |
580 | ||
581 | =head2 regexp optimiser optional | |
582 | ||
583 | The regexp optimiser is not optional. It should configurable to be, to allow | |
584 | its performance to be measured, and its bugs to be easily demonstrated. | |
585 | ||
586 | =head2 UNITCHECK | |
587 | ||
588 | Introduce a new special block, UNITCHECK, which is run at the end of a | |
589 | compilation unit (module, file, eval(STRING) block). This will correspond to | |
590 | the Perl 6 CHECK. Perl 5's CHECK cannot be changed or removed because the | |
591 | O.pm/B.pm backend framework depends on it. | |
592 | ||
593 | =head2 optional optimizer | |
594 | ||
595 | Make the peephole optimizer optional. Currently it performs two tasks as | |
596 | it walks the optree - genuine peephole optimisations, and necessary fixups of | |
597 | ops. It would be good to find an efficient way to switch out the | |
598 | optimisations whilst keeping the fixups. | |
599 | ||
600 | =head2 You WANT *how* many | |
601 | ||
602 | Currently contexts are void, scalar and list. split has a special mechanism in | |
603 | place to pass in the number of return values wanted. It would be useful to | |
604 | have a general mechanism for this, backwards compatible and little speed hit. | |
605 | This would allow proposals such as short circuiting sort to be implemented | |
606 | as a module on CPAN. | |
607 | ||
608 | =head2 lexical aliases | |
609 | ||
610 | Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>. | |
611 | ||
612 | =head2 entersub XS vs Perl | |
613 | ||
614 | At the moment pp_entersub is huge, and has code to deal with entering both | |
615 | perl and XS subroutines. Subroutine implementations rarely change between | |
616 | perl and XS at run time, so investigate using 2 ops to enter subs (one for | |
617 | XS, one for perl) and swap between if a sub is redefined. | |
618 | ||
619 | =head2 Self ties | |
620 | ||
621 | self ties are currently illegal because they caused too many segfaults. Maybe | |
622 | the causes of these could be tracked down and self-ties on all types re- | |
623 | instated. | |
624 | ||
625 | =head2 Optimize away @_ | |
626 | ||
627 | The old perltodo notes "Look at the "reification" code in C<av.c>". | |
628 | ||
629 | =head2 What hooks would assertions need? | |
630 | ||
631 | Assertions are in the core, and work. However, assertions needed to be added | |
632 | as a core patch, rather than an XS module in ext, or a CPAN module, because | |
633 | the core has no hooks in the necessary places. It would be useful to | |
634 | investigate what hooks would need to be added to make it possible to provide | |
635 | the full assertion support from a CPAN module, so that we aren't constraining | |
636 | the imagination of future CPAN authors. | |
637 | ||
638 | ||
639 | ||
640 | ||
641 | ||
642 | =head1 Big projects | |
643 | ||
644 | Tasks that will get your name mentioned in the description of the "Highlights | |
645 | of 5.10" | |
646 | ||
647 | =head2 make ithreads more robust | |
648 | ||
649 | Generally make ithreads more robust. See also L</iCOW> | |
650 | ||
651 | This task is incremental - even a little bit of work on it will help, and | |
652 | will be greatly appreciated. | |
653 | ||
654 | =head2 iCOW | |
655 | ||
656 | Sarathy and Arthur have a proposal for an improved Copy On Write which | |
657 | specifically will be able to COW new ithreads. If this can be implemented | |
658 | it would be a good thing. | |
659 | ||
660 | =head2 (?{...}) closures in regexps | |
661 | ||
662 | Fix (or rewrite) the implementation of the C</(?{...})/> closures. | |
663 | ||
664 | =head2 A re-entrant regexp engine | |
665 | ||
666 | This will allow the use of a regex from inside (?{ }), (??{ }) and | |
667 | (?(?{ })|) constructs. |