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1 | =head1 NAME |
2 | ||
3 | perltodo - Perl TO-DO List | |
4 | ||
5 | =head1 DESCRIPTION | |
e50bb9a1 | 6 | |
0bdfc961 NC |
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. | |
e50bb9a1 | 11 | |
0bdfc961 NC |
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: | |
e50bb9a1 | 15 | |
0bdfc961 | 16 | http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/ |
938c8732 | 17 | |
938c8732 | 18 | |
938c8732 | 19 | |
938c8732 | 20 | |
e50bb9a1 | 21 | |
0bdfc961 | 22 | =head1 Tasks that only need Perl knowledge |
e50bb9a1 | 23 | |
0bdfc961 | 24 | =head2 common test code for timed bail out |
e50bb9a1 | 25 | |
0bdfc961 NC |
26 | Write portable self destruct code for tests to stop them burning CPU in |
27 | infinite loops. This needs to avoid using alarm, as some of the tests are | |
28 | testing alarm/sleep or timers. | |
e50bb9a1 | 29 | |
0bdfc961 | 30 | =head2 POD -> HTML conversion in the core still sucks |
e50bb9a1 | 31 | |
938c8732 | 32 | Which is crazy given just how simple POD purports to be, and how simple HTML |
adebf063 NC |
33 | can be. It's not actually I<as> simple as it sounds, particularly with the |
34 | flexibility POD allows for C<=item>, but it would be good to improve the | |
35 | visual appeal of the HTML generated, and to avoid it having any validation | |
36 | errors. See also L</make HTML install work>, as the layout of installation tree | |
37 | is needed to improve the cross-linking. | |
938c8732 | 38 | |
0bdfc961 | 39 | =head2 Make Schwern poorer |
e50bb9a1 | 40 | |
0bdfc961 NC |
41 | We should have for everything. When all the core's modules are tested, |
42 | Schwern has promised to donate to $500 to TPF. We may need volunteers to | |
43 | hold him upside down and shake vigorously in order to actually extract the | |
44 | cash. | |
3958b146 | 45 | |
0bdfc961 | 46 | See F<t/lib/1_compile.t> for the 3 remaining modules that need tests. |
e50bb9a1 | 47 | |
0bdfc961 | 48 | =head2 Improve the coverage of the core tests |
e50bb9a1 | 49 | |
0bdfc961 NC |
50 | Use Devel::Cover to ascertain the core's test coverage, then add tests that |
51 | are currently missing. | |
30222c0f | 52 | |
0bdfc961 | 53 | =head2 test B |
e50bb9a1 | 54 | |
0bdfc961 | 55 | A full test suite for the B module would be nice. |
e50bb9a1 | 56 | |
0bdfc961 | 57 | =head2 A decent benchmark |
e50bb9a1 | 58 | |
0bdfc961 NC |
59 | perlbench seems impervious to any recent changes made to the perl core. It |
60 | would be useful to have a reasonable general benchmarking suite that roughly | |
61 | represented what current perl programs do, and measurably reported whether | |
62 | tweaks to the core improve, degrade or don't really affect performance, to | |
63 | guide people attempting to optimise the guts of perl. Gisle would welcome | |
64 | new tests for perlbench. | |
6168cf99 | 65 | |
0bdfc961 | 66 | =head2 fix tainting bugs |
6168cf99 | 67 | |
0bdfc961 NC |
68 | Fix the bugs revealed by running the test suite with the C<-t> switch (via |
69 | C<make test.taintwarn>). | |
e50bb9a1 | 70 | |
0bdfc961 | 71 | =head2 Dual life everything |
e50bb9a1 | 72 | |
0bdfc961 NC |
73 | As part of the "dists" plan, anything that doesn't belong in the smallest perl |
74 | distribution needs to be dual lifed. Anything else can be too. Figure out what | |
75 | changes would be needed to package that module and its tests up for CPAN, and | |
76 | do so. Test it with older perl releases, and fix the problems you find. | |
e50bb9a1 | 77 | |
0bdfc961 | 78 | =head2 Improving C<threads::shared> |
722d2a37 | 79 | |
0bdfc961 NC |
80 | Investigate whether C<threads::shared> could share aggregates properly with |
81 | only Perl level changes to shared.pm | |
722d2a37 | 82 | |
0bdfc961 | 83 | =head2 POSIX memory footprint |
e50bb9a1 | 84 | |
0bdfc961 NC |
85 | Ilya observed that use POSIX; eats memory like there's no tomorrow, and at |
86 | various times worked to cut it down. There is probably still fat to cut out - | |
87 | for example POSIX passes Exporter some very memory hungry data structures. | |
e50bb9a1 | 88 | |
4f05ac62 NC |
89 | =head2 Refactor C<xsubpp> to be a thin wrapper around C<ExtUtils::ParseXS> |
90 | ||
91 | C<ExtUtils::ParseXS> encapsulates a version of the C<xsubpp> into a module. | |
92 | In effect this is a code fork, and it's likely that C<xsubpp> has had some | |
93 | bug fixes since the code from C<ExtUtils::ParseXS> was derived. It would be | |
94 | good to merge the differences in, reduce down to 1 canonical implementation, | |
95 | and convert C<xsubpp> to a very thin command line wrapper to | |
96 | C<ExtUtils::ParseXS>. | |
97 | ||
98 | In theory this needs no real C knowledge, as one way of approaching this task | |
99 | is to ensure that C<ExtUtils::ParseXS> generates identical output to C<xsubpp> | |
100 | for input XS files, which does not require understanding the contents of the | |
101 | output C file. However, some C knowledge is likely to help with testing, and | |
102 | locating/producing comprehensive test cases. | |
e50bb9a1 | 103 | |
e50bb9a1 | 104 | |
e50bb9a1 | 105 | |
e50bb9a1 | 106 | |
adebf063 | 107 | |
adebf063 | 108 | |
0bdfc961 | 109 | =head1 Tasks that need a little sysadmin-type knowledge |
e50bb9a1 | 110 | |
0bdfc961 NC |
111 | Or if you prefer, tasks that you would learn from, and broaden your skills |
112 | base... | |
e50bb9a1 | 113 | |
cd793d32 | 114 | =head2 make HTML install work |
e50bb9a1 | 115 | |
adebf063 NC |
116 | There is an C<installhtml> target in the Makefile. It's marked as |
117 | "experimental". It would be good to get this tested, make it work reliably, and | |
118 | remove the "experimental" tag. This would include | |
119 | ||
120 | =over 4 | |
121 | ||
122 | =item 1 | |
123 | ||
124 | Checking that cross linking between various parts of the documentation works. | |
125 | In particular that links work between the modules (files with POD in F<lib/>) | |
126 | and the core documentation (files in F<pod/>) | |
127 | ||
128 | =item 2 | |
129 | ||
130 | Work out how to split perlfunc into chunks, preferably one per function group, | |
131 | preferably with general case code that could be used elsewhere. Challenges | |
132 | here are correctly identifying the groups of functions that go together, and | |
133 | making the right named external cross-links point to the right page. Things to | |
134 | be aware of are C<-X>, groups such as C<getpwnam> to C<endservent>, two or | |
135 | more C<=items> giving the different parameter lists, such as | |
136 | ||
137 | =item substr EXPR,OFFSET,LENGTH,REPLACEMENT | |
138 | ||
139 | =item substr EXPR,OFFSET,LENGTH | |
140 | ||
141 | =item substr EXPR,OFFSET | |
142 | ||
143 | and different parameter lists having different meanings. (eg C<select>) | |
144 | ||
145 | =back | |
3a89a73c | 146 | |
0bdfc961 NC |
147 | =head2 compressed man pages |
148 | ||
149 | Be able to install them. This would probably need a configure test to see how | |
150 | the system does compressed man pages (same directory/different directory? | |
151 | same filename/different filename), as well as tweaking the F<installman> script | |
152 | to compress as necessary. | |
153 | ||
30222c0f NC |
154 | =head2 Add a code coverage target to the Makefile |
155 | ||
156 | Make it easy for anyone to run Devel::Cover on the core's tests. The steps | |
157 | to do this manually are roughly | |
158 | ||
159 | =over 4 | |
160 | ||
161 | =item * | |
162 | ||
163 | do a normal C<Configure>, but include Devel::Cover as a module to install | |
164 | (see F<INSTALL> for how to do this) | |
165 | ||
166 | =item * | |
167 | ||
168 | make perl | |
169 | ||
170 | =item * | |
171 | ||
172 | cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness | |
173 | ||
174 | =item * | |
175 | ||
176 | Process the resulting Devel::Cover database | |
177 | ||
178 | =back | |
179 | ||
180 | This just give you the coverage of the F<.pm>s. To also get the C level | |
181 | coverage you need to | |
182 | ||
183 | =over 4 | |
184 | ||
185 | =item * | |
186 | ||
187 | Additionally tell C<Configure> to use the appropriate C compiler flags for | |
188 | C<gcov> | |
189 | ||
190 | =item * | |
191 | ||
192 | make perl.gcov | |
193 | ||
194 | (instead of C<make perl>) | |
195 | ||
196 | =item * | |
197 | ||
198 | After running the tests run C<gcov> to generate all the F<.gcov> files. | |
199 | (Including down in the subdirectories of F<ext/> | |
200 | ||
201 | =item * | |
202 | ||
203 | (From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files | |
204 | to get their stats into the cover_db directory. | |
205 | ||
206 | =item * | |
207 | ||
208 | Then process the Devel::Cover database | |
209 | ||
210 | =back | |
211 | ||
212 | It would be good to add a single switch to C<Configure> to specify that you | |
213 | wanted to perform perl level coverage, and another to specify C level | |
214 | coverage, and have C<Configure> and the F<Makefile> do all the right things | |
215 | automatically. | |
216 | ||
0bdfc961 NC |
217 | =head2 Make Config.pm cope with differences between build and installed perl |
218 | ||
219 | Quite often vendors ship a perl binary compiled with their (pay-for) | |
220 | compilers. People install a free compiler, such as gcc. To work out how to | |
221 | build extensions, Perl interrogates C<%Config>, so in this situation | |
222 | C<%Config> describes compilers that aren't there, and extension building | |
223 | fails. This forces people into choosing between re-compiling perl themselves | |
224 | using the compiler they have, or only using modules that the vendor ships. | |
225 | ||
226 | It would be good to find a way teach C<Config.pm> about the installation setup, | |
227 | possibly involving probing at install time or later, so that the C<%Config> in | |
228 | a binary distribution better describes the installed machine, when the | |
229 | installed machine differs from the build machine in some significant way. | |
230 | ||
231 | =head2 Relocatable perl | |
232 | ||
233 | The C level patches needed to create a relocatable perl binary are done, as | |
234 | is the work on Config.pm. All that's left to do is the C<Configure> tweaking | |
235 | to let people specify how they want to do the install. | |
236 | ||
46925299 | 237 | =head2 make parallel builds work |
0bdfc961 | 238 | |
46925299 NC |
239 | Currently parallel builds (such as C<make -j3>) don't work reliably. We believe |
240 | that this is due to incomplete dependency specification in the F<Makefile>. | |
241 | It would be good if someone were able to track down the causes of these | |
242 | problems, so that parallel builds worked properly. | |
0bdfc961 | 243 | |
8523e164 | 244 | |
0bdfc961 NC |
245 | |
246 | ||
247 | =head1 Tasks that need a little C knowledge | |
248 | ||
249 | These tasks would need a little C knowledge, but don't need any specific | |
250 | background or experience with XS, or how the Perl interpreter works | |
251 | ||
252 | =head2 Make it clear from -v if this is the exact official release | |
89007cb3 NC |
253 | |
254 | Currently perl from p4/rsync ships with a patchlevel.h file that usually | |
255 | defines one local patch, of the form "MAINT12345" or "RC1". The output of | |
256 | perl -v doesn't report that a perl isn't an official release, and this | |
257 | information can get lost in bugs reports. Because of this, the minor version | |
fa11829f | 258 | isn't bumped up until RC time, to minimise the possibility of versions of perl |
89007cb3 NC |
259 | escaping that believe themselves to be newer than they actually are. |
260 | ||
261 | It would be useful to find an elegant way to have the "this is an interim | |
262 | maintenance release" or "this is a release candidate" in the terse -v output, | |
263 | and have it so that it's easy for the pumpking to remove this just as the | |
264 | release tarball is rolled up. This way the version pulled out of rsync would | |
265 | always say "I'm a development release" and it would be safe to bump the | |
266 | reported minor version as soon as a release ships, which would aid perl | |
267 | developers. | |
268 | ||
0bdfc961 NC |
269 | This task is really about thinking of an elegant way to arrange the C source |
270 | such that it's trivial for the Pumpking to flag "this is an official release" | |
271 | when making a tarball, yet leave the default source saying "I'm not the | |
272 | official release". | |
273 | ||
0f788cd2 NC |
274 | =head2 Ordering of "global" variables. |
275 | ||
276 | F<thrdvar.h> and F<intrpvarh> define the "global" variables that need to be | |
277 | per-thread under ithreads, where the variables are actually elements in a | |
278 | structure. As C dictates, the variables must be laid out in order of | |
279 | declaration. There is a comment | |
280 | C</* Important ones in the first cache line (if alignment is done right) */> | |
281 | which implies that at some point in the past the ordering was carefully chosen | |
282 | (at least in part). However, it's clear that the ordering is less than perfect, | |
283 | as currently there are things such as 7 C<bool>s in a row, then something | |
284 | typically requiring 4 byte alignment, and then an odd C<bool> later on. | |
285 | (C<bool>s are typically defined as C<char>s). So it would be good for someone | |
286 | to review the ordering of the variables, to see how much alignment padding can | |
287 | be removed. | |
288 | ||
0bdfc961 NC |
289 | =head2 bincompat functions |
290 | ||
291 | There are lots of functions which are retained for binary compatibility. | |
292 | Clean these up. Move them to mathom.c, and don't compile for blead? | |
293 | ||
62403a3c NC |
294 | =head2 am I hot or not? |
295 | ||
296 | The idea of F<pp_hot.c> is that it contains the I<hot> ops, the ops that are | |
297 | most commonly used. The idea is that by grouping them, their object code will | |
298 | be adjacent in the executable, so they have a greater chance of already being | |
299 | in the CPU cache (or swapped in) due to being near another op already in use. | |
300 | ||
301 | Except that it's not clear if these really are the most commonly used ops. So | |
302 | anyone feeling like exercising their skill with coverage and profiling tools | |
303 | might want to determine what ops I<really> are the most commonly used. And in | |
304 | turn suggest evictions and promotions to achieve a better F<pp_hot.c>. | |
305 | ||
c99e3826 NC |
306 | =head2 emulate the per-thread memory pool on Unix |
307 | ||
308 | For Windows, ithreads allocates memory for each thread from a separate pool, | |
309 | which it discards at thread exit. It also checks that memory is free()d to | |
310 | the correct pool. Neither check is done on Unix, so code developed there won't | |
311 | be subject to such strictures, so can harbour bugs that only show up when the | |
312 | code reaches Windows. | |
313 | ||
314 | It would be good to be able to optionally emulate the Window pool system on | |
315 | Unix, to let developers who only have access to Unix, or want to use | |
316 | Unix-specific debugging tools, check for these problems. To do this would | |
317 | involve figuring out how the C<PerlMem_*> macros wrap C<malloc()> access, and | |
318 | providing a layer that records/checks the identity of the thread making the | |
319 | call, and recording all the memory allocated by each thread via this API so | |
320 | that it can be summarily free()d at thread exit. One implementation idea | |
321 | would be to increase the size of allocation, and store the C<my_perl> pointer | |
322 | (to identify the thread) at the start, along with pointers to make a linked | |
323 | list of blocks for this thread. To avoid alignment problems it would be | |
324 | necessary to do something like | |
325 | ||
326 | union memory_header_padded { | |
327 | struct memory_header { | |
328 | void *thread_id; /* For my_perl */ | |
329 | void *next; /* Pointer to next block for this thread */ | |
330 | } data; | |
331 | long double padding; /* whatever type has maximal alignment constraint */ | |
332 | }; | |
333 | ||
334 | ||
335 | although C<long double> might not be the only type to add to the padding | |
336 | union. | |
62403a3c | 337 | |
077e3186 NC |
338 | =head2 reduce duplication in sv_setsv_flags |
339 | ||
340 | C<Perl_sv_setsv_flags> has a comment | |
341 | C</* There's a lot of redundancy below but we're going for speed here */> | |
342 | ||
343 | Whilst this was true 10 years ago, the growing disparity between RAM and CPU | |
344 | speeds mean that the trade offs have changed. In addition, the duplicate code | |
345 | adds to the maintenance burden. It would be good to see how much of the | |
346 | redundancy can be pruned, particular in the less common paths. (Profiling | |
347 | tools at the ready...). For example, why does the test for | |
348 | "Can't redefine active sort subroutine" need to occur in two places? | |
349 | ||
0bdfc961 NC |
350 | |
351 | ||
352 | ||
0bdfc961 | 353 | =head1 Tasks that need a knowledge of XS |
e50bb9a1 | 354 | |
0bdfc961 NC |
355 | These tasks would need C knowledge, and roughly the level of knowledge of |
356 | the perl API that comes from writing modules that use XS to interface to | |
357 | C. | |
358 | ||
359 | =head2 IPv6 | |
360 | ||
361 | Clean this up. Check everything in core works | |
362 | ||
4a750395 NC |
363 | =head2 shrink C<GV>s, C<CV>s |
364 | ||
365 | By removing unused elements and careful re-ordering, the structures for C<AV>s | |
366 | and C<HV>s have recently been shrunk considerably. It's probable that the same | |
367 | approach would find savings in C<GV>s and C<CV>s, if not all the other | |
368 | larger-than-C<PVMG> types. | |
369 | ||
e593da1a NC |
370 | =head2 merge Perl_sv_2[inpu]v |
371 | ||
372 | There's a lot of code shared between C<Perl_sv_2iv_flags>, | |
373 | C<Perl_sv_2uv_flags>, C<Perl_sv_2nv>, and C<Perl_sv_2pv_flags>. It would be | |
374 | interesting to see if some of it can be merged into common shared static | |
375 | functions. In particular, C<Perl_sv_2uv_flags> started out as a cut&paste | |
376 | from C<Perl_sv_2iv_flags> around 5.005_50 time, and it may be possible to | |
377 | replace both with a single function that returns a value or union which is | |
378 | split out by the macros in F<sv.h> | |
379 | ||
0bdfc961 NC |
380 | =head2 UTF8 caching code |
381 | ||
382 | The string position/offset cache is not optional. It should be. | |
383 | ||
384 | =head2 Implicit Latin 1 => Unicode translation | |
385 | ||
386 | Conversions from byte strings to UTF-8 currently map high bit characters | |
387 | to Unicode without translation (or, depending on how you look at it, by | |
388 | implicitly assuming that the byte strings are in Latin-1). As perl assumes | |
389 | the C locale by default, upgrading a string to UTF-8 may change the | |
390 | meaning of its contents regarding character classes, case mapping, etc. | |
391 | This should probably emit a warning (at least). | |
392 | ||
393 | This task is incremental - even a little bit of work on it will help. | |
e50bb9a1 | 394 | |
cd793d32 | 395 | =head2 autovivification |
e50bb9a1 | 396 | |
cd793d32 | 397 | Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict; |
e50bb9a1 | 398 | |
0bdfc961 | 399 | This task is incremental - even a little bit of work on it will help. |
e50bb9a1 | 400 | |
0bdfc961 | 401 | =head2 Unicode in Filenames |
e50bb9a1 | 402 | |
0bdfc961 NC |
403 | chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open, |
404 | opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen, | |
405 | system, truncate, unlink, utime, -X. All these could potentially accept | |
406 | Unicode filenames either as input or output (and in the case of system | |
407 | and qx Unicode in general, as input or output to/from the shell). | |
408 | Whether a filesystem - an operating system pair understands Unicode in | |
409 | filenames varies. | |
e50bb9a1 | 410 | |
0bdfc961 NC |
411 | Known combinations that have some level of understanding include |
412 | Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac | |
413 | OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to | |
414 | create Unicode filenames, what forms of Unicode are accepted and used | |
415 | (UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used, | |
416 | and so on, varies. Finding the right level of interfacing to Perl | |
417 | requires some thought. Remember that an OS does not implicate a | |
418 | filesystem. | |
e50bb9a1 | 419 | |
0bdfc961 NC |
420 | (The Windows -C command flag "wide API support" has been at least |
421 | temporarily retired in 5.8.1, and the -C has been repurposed, see | |
422 | L<perlrun>.) | |
969e704b | 423 | |
0bdfc961 | 424 | =head2 Unicode in %ENV |
969e704b | 425 | |
0bdfc961 | 426 | Currently the %ENV entries are always byte strings. |
e50bb9a1 | 427 | |
0bdfc961 | 428 | =head2 use less 'memory' |
e50bb9a1 | 429 | |
0bdfc961 NC |
430 | Investigate trade offs to switch out perl's choices on memory usage. |
431 | Particularly perl should be able to give memory back. | |
e50bb9a1 | 432 | |
0bdfc961 | 433 | This task is incremental - even a little bit of work on it will help. |
0abe3f7c | 434 | |
0bdfc961 | 435 | =head2 Re-implement C<:unique> in a way that is actually thread-safe |
0abe3f7c | 436 | |
0bdfc961 NC |
437 | The old implementation made bad assumptions on several levels. A good 90% |
438 | solution might be just to make C<:unique> work to share the string buffer | |
439 | of SvPVs. That way large constant strings can be shared between ithreads, | |
440 | such as the configuration information in F<Config>. | |
0abe3f7c | 441 | |
0bdfc961 | 442 | =head2 Make tainting consistent |
0abe3f7c | 443 | |
0bdfc961 NC |
444 | Tainting would be easier to use if it didn't take documented shortcuts and |
445 | allow taint to "leak" everywhere within an expression. | |
0abe3f7c | 446 | |
0bdfc961 | 447 | =head2 readpipe(LIST) |
0abe3f7c | 448 | |
0bdfc961 NC |
449 | system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid |
450 | running a shell. readpipe() (the function behind qx//) could be similarly | |
451 | extended. | |
0abe3f7c | 452 | |
e50bb9a1 | 453 | |
e50bb9a1 | 454 | |
e50bb9a1 | 455 | |
f86a8bc5 | 456 | |
0bdfc961 | 457 | =head1 Tasks that need a knowledge of the interpreter |
3298bd4d | 458 | |
0bdfc961 NC |
459 | These tasks would need C knowledge, and knowledge of how the interpreter works, |
460 | or a willingness to learn. | |
3298bd4d | 461 | |
0bdfc961 NC |
462 | =head2 lexical pragmas |
463 | ||
464 | Reimplement the mechanism of lexical pragmas to be more extensible. Fix | |
465 | current pragmas that don't work well (or at all) with lexical scopes or in | |
466 | run-time eval(STRING) (C<sort>, C<re>, C<encoding> for example). MJD has a | |
467 | preliminary patch that implements this. | |
0562c0e3 | 468 | |
d10fc472 | 469 | =head2 Attach/detach debugger from running program |
1626a787 | 470 | |
cd793d32 NC |
471 | The old perltodo notes "With C<gdb>, you can attach the debugger to a running |
472 | program if you pass the process ID. It would be good to do this with the Perl | |
0bdfc961 NC |
473 | debugger on a running Perl program, although I'm not sure how it would be |
474 | done." ssh and screen do this with named pipes in /tmp. Maybe we can too. | |
1626a787 | 475 | |
0bdfc961 | 476 | =head2 inlining autoloaded constants |
d10fc472 | 477 | |
0bdfc961 NC |
478 | Currently the optimiser can inline constants when expressed as subroutines |
479 | with prototype ($) that return a constant. Likewise, many packages wrapping | |
480 | C libraries export lots of constants as subroutines which are AUTOLOADed on | |
481 | demand. However, these have no prototypes, so can't be seen as constants by | |
482 | the optimiser. Some way of cheaply (low syntax, low memory overhead) to the | |
483 | perl compiler that a name is a constant would be great, so that it knows to | |
484 | call the AUTOLOAD routine at compile time, and then inline the constant. | |
80b46460 | 485 | |
0bdfc961 | 486 | =head2 Constant folding |
80b46460 | 487 | |
0bdfc961 NC |
488 | The peephole optimiser should trap errors during constant folding, and give |
489 | up on the folding, rather than bailing out at compile time. It is quite | |
490 | possible that the unfoldable constant is in unreachable code, eg something | |
491 | akin to C<$a = 0/0 if 0;> | |
492 | ||
493 | =head2 LVALUE functions for lists | |
494 | ||
495 | The old perltodo notes that lvalue functions don't work for list or hash | |
496 | slices. This would be good to fix. | |
497 | ||
498 | =head2 LVALUE functions in the debugger | |
499 | ||
500 | The old perltodo notes that lvalue functions don't work in the debugger. This | |
501 | would be good to fix. | |
502 | ||
503 | =head2 _ prototype character | |
504 | ||
505 | Study the possibility of adding a new prototype character, C<_>, meaning | |
506 | "this argument defaults to $_". | |
507 | ||
508 | =head2 @INC source filter to Filter::Simple | |
509 | ||
510 | The second return value from a sub in @INC can be a source filter. This isn't | |
511 | documented. It should be changed to use Filter::Simple, tested and documented. | |
512 | ||
513 | =head2 regexp optimiser optional | |
514 | ||
515 | The regexp optimiser is not optional. It should configurable to be, to allow | |
516 | its performance to be measured, and its bugs to be easily demonstrated. | |
517 | ||
518 | =head2 UNITCHECK | |
519 | ||
520 | Introduce a new special block, UNITCHECK, which is run at the end of a | |
521 | compilation unit (module, file, eval(STRING) block). This will correspond to | |
522 | the Perl 6 CHECK. Perl 5's CHECK cannot be changed or removed because the | |
523 | O.pm/B.pm backend framework depends on it. | |
524 | ||
525 | =head2 optional optimizer | |
526 | ||
527 | Make the peephole optimizer optional. Currently it performs two tasks as | |
528 | it walks the optree - genuine peephole optimisations, and necessary fixups of | |
529 | ops. It would be good to find an efficient way to switch out the | |
530 | optimisations whilst keeping the fixups. | |
531 | ||
532 | =head2 You WANT *how* many | |
533 | ||
534 | Currently contexts are void, scalar and list. split has a special mechanism in | |
535 | place to pass in the number of return values wanted. It would be useful to | |
536 | have a general mechanism for this, backwards compatible and little speed hit. | |
537 | This would allow proposals such as short circuiting sort to be implemented | |
538 | as a module on CPAN. | |
539 | ||
540 | =head2 lexical aliases | |
541 | ||
542 | Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>. | |
543 | ||
544 | =head2 entersub XS vs Perl | |
545 | ||
546 | At the moment pp_entersub is huge, and has code to deal with entering both | |
547 | perl and XS subroutines. Subroutine implementations rarely change between | |
548 | perl and XS at run time, so investigate using 2 ops to enter subs (one for | |
549 | XS, one for perl) and swap between if a sub is redefined. | |
2810d901 NC |
550 | |
551 | =head2 Self ties | |
552 | ||
553 | self ties are currently illegal because they caused too many segfaults. Maybe | |
554 | the causes of these could be tracked down and self-ties on all types re- | |
555 | instated. | |
0bdfc961 NC |
556 | |
557 | =head2 Optimize away @_ | |
558 | ||
559 | The old perltodo notes "Look at the "reification" code in C<av.c>". | |
560 | ||
561 | =head2 switch ops | |
562 | ||
563 | The old perltodo notes "Although we have C<Switch.pm> in core, Larry points to | |
564 | the dormant C<nswitch> and C<cswitch> ops in F<pp.c>; using these opcodes would | |
565 | be much faster." | |
566 | ||
567 | =head2 What hooks would assertions need? | |
568 | ||
569 | Assertions are in the core, and work. However, assertions needed to be added | |
570 | as a core patch, rather than an XS module in ext, or a CPAN module, because | |
571 | the core has no hooks in the necessary places. It would be useful to | |
572 | investigate what hooks would need to be added to make it possible to provide | |
573 | the full assertion support from a CPAN module, so that we aren't constraining | |
574 | the imagination of future CPAN authors. | |
575 | ||
576 | ||
577 | ||
578 | ||
579 | ||
580 | ||
581 | ||
582 | =head1 Big projects | |
583 | ||
584 | Tasks that will get your name mentioned in the description of the "Highlights | |
585 | of 5.10" | |
586 | ||
587 | =head2 make ithreads more robust | |
588 | ||
589 | Generally make ithreads more robust. See also L<iCOW> | |
590 | ||
591 | This task is incremental - even a little bit of work on it will help, and | |
592 | will be greatly appreciated. | |
593 | ||
594 | =head2 iCOW | |
595 | ||
596 | Sarathy and Arthur have a proposal for an improved Copy On Write which | |
597 | specifically will be able to COW new ithreads. If this can be implemented | |
598 | it would be a good thing. | |
599 | ||
600 | =head2 (?{...}) closures in regexps | |
601 | ||
602 | Fix (or rewrite) the implementation of the C</(?{...})/> closures. | |
603 | ||
604 | =head2 A re-entrant regexp engine | |
605 | ||
606 | This will allow the use of a regex from inside (?{ }), (??{ }) and | |
607 | (?(?{ })|) constructs. |