This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
I shrunk struct context, so remove it from perltodo.
[perl5.git] / pod / perltodo.pod
CommitLineData
7711098a
GS
1=head1 NAME
2
3perltodo - Perl TO-DO List
4
5=head1 DESCRIPTION
e50bb9a1 6
0bdfc961
NC
7This is a list of wishes for Perl. The tasks we think are smaller or easier
8are listed first. Anyone is welcome to work on any of these, but it's a good
9idea to first contact I<perl5-porters@perl.org> to avoid duplication of
10effort. By all means contact a pumpking privately first if you prefer.
e50bb9a1 11
0bdfc961
NC
12Whilst patches to make the list shorter are most welcome, ideas to add to
13the list are also encouraged. Check the perl5-porters archives for past
14ideas, 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
617eabfa
NC
18What can we offer you in return? Fame, fortune, and everlasting glory? Maybe
19not, but if your patch is incorporated, then we'll add your name to the
20F<AUTHORS> file, which ships in the official distribution. How many other
21programming languages offer you 1 line of immortality?
938c8732 22
4e577f8b 23=head1 The roadmap to 5.10
938c8732 24
4e577f8b
NC
25The roadmap to 5.10 envisages feature based releases, as various items in this
26TODO are completed.
27
02f21748 28=head2 Needed for a 5.9.5 release
4e577f8b
NC
29
30=over
31
32=item *
c1f116f6 33
02f21748 34Review smart match semantics in light of Perl 6 developments.
4e577f8b
NC
35
36=item *
c1f116f6 37
02f21748
RGS
38Review assertions. Review syntax to combine assertions. Assertions could take
39advantage of the lexical pragmas work. L</What hooks would assertions need?>
4e577f8b 40
c1f116f6
RGS
41=item *
42
02f21748 43C<encoding> should be turned into a lexical pragma (probably).
c1f116f6 44
4e577f8b
NC
45=back
46
47=head2 Needed for a 5.9.6 release
48
49Stabilisation. If all goes well, this will be the equivalent of a 5.10-beta.
e50bb9a1 50
0bdfc961 51=head1 Tasks that only need Perl knowledge
e50bb9a1 52
0bdfc961 53=head2 common test code for timed bail out
e50bb9a1 54
0bdfc961
NC
55Write portable self destruct code for tests to stop them burning CPU in
56infinite loops. This needs to avoid using alarm, as some of the tests are
57testing alarm/sleep or timers.
e50bb9a1 58
0bdfc961 59=head2 POD -> HTML conversion in the core still sucks
e50bb9a1 60
938c8732 61Which is crazy given just how simple POD purports to be, and how simple HTML
adebf063
NC
62can be. It's not actually I<as> simple as it sounds, particularly with the
63flexibility POD allows for C<=item>, but it would be good to improve the
64visual appeal of the HTML generated, and to avoid it having any validation
65errors. See also L</make HTML install work>, as the layout of installation tree
66is needed to improve the cross-linking.
938c8732 67
dc0fb092
SP
68The addition of C<Pod::Simple> and its related modules may make this task
69easier to complete.
70
aa237293
NC
71=head2 Parallel testing
72
b2e2905c 73(This probably impacts much more than the core: also the Test::Harness
02f21748
RGS
74and TAP::* modules on CPAN.)
75
aa237293
NC
76The core regression test suite is getting ever more comprehensive, which has
77the side effect that it takes longer to run. This isn't so good. Investigate
78whether it would be feasible to give the harness script the B<option> of
79running sets of tests in parallel. This would be useful for tests in
80F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>.
81
82Questions to answer
83
84=over 4
85
86=item 1
87
88How does screen layout work when you're running more than one test?
89
90=item 2
91
92How does the caller of test specify how many tests to run in parallel?
93
94=item 3
95
96How do setup/teardown tests identify themselves?
97
98=back
99
100Pugs already does parallel testing - can their approach be re-used?
101
0bdfc961 102=head2 Make Schwern poorer
e50bb9a1 103
613bd4f7 104We should have tests for everything. When all the core's modules are tested,
0bdfc961
NC
105Schwern has promised to donate to $500 to TPF. We may need volunteers to
106hold him upside down and shake vigorously in order to actually extract the
107cash.
3958b146 108
0bdfc961 109=head2 Improve the coverage of the core tests
e50bb9a1 110
02f21748
RGS
111Use Devel::Cover to ascertain the core modules's test coverage, then add
112tests that are currently missing.
30222c0f 113
0bdfc961 114=head2 test B
e50bb9a1 115
0bdfc961 116A full test suite for the B module would be nice.
e50bb9a1 117
0bdfc961 118=head2 A decent benchmark
e50bb9a1 119
617eabfa 120C<perlbench> seems impervious to any recent changes made to the perl core. It
0bdfc961
NC
121would be useful to have a reasonable general benchmarking suite that roughly
122represented what current perl programs do, and measurably reported whether
123tweaks to the core improve, degrade or don't really affect performance, to
124guide people attempting to optimise the guts of perl. Gisle would welcome
125new tests for perlbench.
6168cf99 126
0bdfc961 127=head2 fix tainting bugs
6168cf99 128
0bdfc961
NC
129Fix the bugs revealed by running the test suite with the C<-t> switch (via
130C<make test.taintwarn>).
e50bb9a1 131
0bdfc961 132=head2 Dual life everything
e50bb9a1 133
0bdfc961
NC
134As part of the "dists" plan, anything that doesn't belong in the smallest perl
135distribution needs to be dual lifed. Anything else can be too. Figure out what
136changes would be needed to package that module and its tests up for CPAN, and
137do so. Test it with older perl releases, and fix the problems you find.
e50bb9a1 138
0bdfc961 139=head2 Improving C<threads::shared>
722d2a37 140
0bdfc961
NC
141Investigate whether C<threads::shared> could share aggregates properly with
142only Perl level changes to shared.pm
722d2a37 143
0bdfc961 144=head2 POSIX memory footprint
e50bb9a1 145
0bdfc961
NC
146Ilya observed that use POSIX; eats memory like there's no tomorrow, and at
147various times worked to cut it down. There is probably still fat to cut out -
148for example POSIX passes Exporter some very memory hungry data structures.
e50bb9a1 149
eed36644
NC
150=head2 embed.pl/makedef.pl
151
152There is a script F<embed.pl> that generates several header files to prefix
153all of Perl's symbols in a consistent way, to provide some semblance of
154namespace support in C<C>. Functions are declared in F<embed.fnc>, variables
155in F<interpvar.h> and F<thrdvar.h>. Quite a few of the functions and variables
156are conditionally declared there, using C<#ifdef>. However, F<embed.pl>
157doesn't understand the C macros, so the rules about which symbols are present
158when is duplicated in F<makedef.pl>. Writing things twice is bad, m'kay.
159It would be good to teach C<embed.pl> to understand the conditional
160compilation, and hence remove the duplication, and the mistakes it has caused.
e50bb9a1 161
0bdfc961 162=head1 Tasks that need a little sysadmin-type knowledge
e50bb9a1 163
0bdfc961
NC
164Or if you prefer, tasks that you would learn from, and broaden your skills
165base...
e50bb9a1 166
cd793d32 167=head2 make HTML install work
e50bb9a1 168
adebf063
NC
169There is an C<installhtml> target in the Makefile. It's marked as
170"experimental". It would be good to get this tested, make it work reliably, and
171remove the "experimental" tag. This would include
172
173=over 4
174
175=item 1
176
177Checking that cross linking between various parts of the documentation works.
178In particular that links work between the modules (files with POD in F<lib/>)
179and the core documentation (files in F<pod/>)
180
181=item 2
182
617eabfa
NC
183Work out how to split C<perlfunc> into chunks, preferably one per function
184group, preferably with general case code that could be used elsewhere.
185Challenges here are correctly identifying the groups of functions that go
186together, and making the right named external cross-links point to the right
187page. Things to be aware of are C<-X>, groups such as C<getpwnam> to
188C<endservent>, two or more C<=items> giving the different parameter lists, such
189as
adebf063
NC
190
191 =item substr EXPR,OFFSET,LENGTH,REPLACEMENT
adebf063 192 =item substr EXPR,OFFSET,LENGTH
adebf063
NC
193 =item substr EXPR,OFFSET
194
195and different parameter lists having different meanings. (eg C<select>)
196
197=back
3a89a73c 198
0bdfc961
NC
199=head2 compressed man pages
200
201Be able to install them. This would probably need a configure test to see how
202the system does compressed man pages (same directory/different directory?
203same filename/different filename), as well as tweaking the F<installman> script
204to compress as necessary.
205
30222c0f
NC
206=head2 Add a code coverage target to the Makefile
207
208Make it easy for anyone to run Devel::Cover on the core's tests. The steps
209to do this manually are roughly
210
211=over 4
212
213=item *
214
215do a normal C<Configure>, but include Devel::Cover as a module to install
216(see F<INSTALL> for how to do this)
217
218=item *
219
220 make perl
221
222=item *
223
224 cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness
225
226=item *
227
228Process the resulting Devel::Cover database
229
230=back
231
232This just give you the coverage of the F<.pm>s. To also get the C level
233coverage you need to
234
235=over 4
236
237=item *
238
239Additionally tell C<Configure> to use the appropriate C compiler flags for
240C<gcov>
241
242=item *
243
244 make perl.gcov
245
246(instead of C<make perl>)
247
248=item *
249
250After running the tests run C<gcov> to generate all the F<.gcov> files.
251(Including down in the subdirectories of F<ext/>
252
253=item *
254
255(From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files
256to get their stats into the cover_db directory.
257
258=item *
259
260Then process the Devel::Cover database
261
262=back
263
264It would be good to add a single switch to C<Configure> to specify that you
265wanted to perform perl level coverage, and another to specify C level
266coverage, and have C<Configure> and the F<Makefile> do all the right things
267automatically.
268
02f21748 269=head2 Make Config.pm cope with differences between built and installed perl
0bdfc961
NC
270
271Quite often vendors ship a perl binary compiled with their (pay-for)
272compilers. People install a free compiler, such as gcc. To work out how to
273build extensions, Perl interrogates C<%Config>, so in this situation
274C<%Config> describes compilers that aren't there, and extension building
275fails. This forces people into choosing between re-compiling perl themselves
276using the compiler they have, or only using modules that the vendor ships.
277
278It would be good to find a way teach C<Config.pm> about the installation setup,
279possibly involving probing at install time or later, so that the C<%Config> in
280a binary distribution better describes the installed machine, when the
281installed machine differs from the build machine in some significant way.
282
728f4ecd
NC
283=head2 linker specification files
284
285Some platforms mandate that you provide a list of a shared library's external
286symbols to the linker, so the core already has the infrastructure in place to
287do this for generating shared perl libraries. My understanding is that the
288GNU toolchain can accept an optional linker specification file, and restrict
289visibility just to symbols declared in that file. It would be good to extend
290F<makedef.pl> to support this format, and to provide a means within
291C<Configure> to enable it. This would allow Unix users to test that the
292export list is correct, and to build a perl that does not pollute the global
293namespace with private symbols.
294
a229ae3b
RGS
295=head2 Cross-compile support
296
297Currently C<Configure> understands C<-Dusecrosscompile> option. This option
298arranges for building C<miniperl> for TARGET machine, so this C<miniperl> is
299assumed then to be copied to TARGET machine and used as a replacement of full
300C<perl> executable.
301
d1307786 302This could be done little differently. Namely C<miniperl> should be built for
a229ae3b 303HOST and then full C<perl> with extensions should be compiled for TARGET.
d1307786
JH
304This, however, might require extra trickery for %Config: we have one config
305first for HOST and then another for TARGET.
0bdfc961
NC
306
307=head1 Tasks that need a little C knowledge
308
309These tasks would need a little C knowledge, but don't need any specific
310background or experience with XS, or how the Perl interpreter works
311
312=head2 Make it clear from -v if this is the exact official release
89007cb3 313
617eabfa
NC
314Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that
315usually defines one local patch, of the form "MAINT12345" or "RC1". The output
316of perl -v doesn't report that a perl isn't an official release, and this
89007cb3 317information can get lost in bugs reports. Because of this, the minor version
fa11829f 318isn't bumped up until RC time, to minimise the possibility of versions of perl
89007cb3
NC
319escaping that believe themselves to be newer than they actually are.
320
321It would be useful to find an elegant way to have the "this is an interim
322maintenance release" or "this is a release candidate" in the terse -v output,
323and have it so that it's easy for the pumpking to remove this just as the
324release tarball is rolled up. This way the version pulled out of rsync would
325always say "I'm a development release" and it would be safe to bump the
326reported minor version as soon as a release ships, which would aid perl
327developers.
328
0bdfc961
NC
329This task is really about thinking of an elegant way to arrange the C source
330such that it's trivial for the Pumpking to flag "this is an official release"
331when making a tarball, yet leave the default source saying "I'm not the
332official release".
333
0f788cd2
NC
334=head2 Ordering of "global" variables.
335
336F<thrdvar.h> and F<intrpvarh> define the "global" variables that need to be
337per-thread under ithreads, where the variables are actually elements in a
338structure. As C dictates, the variables must be laid out in order of
339declaration. There is a comment
340C</* Important ones in the first cache line (if alignment is done right) */>
341which implies that at some point in the past the ordering was carefully chosen
342(at least in part). However, it's clear that the ordering is less than perfect,
343as currently there are things such as 7 C<bool>s in a row, then something
344typically requiring 4 byte alignment, and then an odd C<bool> later on.
345(C<bool>s are typically defined as C<char>s). So it would be good for someone
346to review the ordering of the variables, to see how much alignment padding can
347be removed.
348
d7939546
NC
349It's also worth checking that all variables are actually used. Perl 5.8.0
350shipped with C<PL_nrs> still defined in F<thrdvar.h>, despite it being unused
351since a change over a year earlier. Had this been spotted before release, it
352could have been removed, but now it has to remain in the 5.8.x releases to
353keep the structure the same size, to retain binary compatibility.
354
c1ab7b38
NC
355It's probably worth checking if all need to be the types they are. For example
356
357 PERLVAR(Ierror_count, I32) /* how many errors so far, max 10 */
358
359might work as well if stored in a signed (or unsigned) 8 bit value, if the
360comment is accurate. C<PL_multi_open> and C<PL_multi_close> can probably
361become C<char>s. Finding variables to downsize coupled with rearrangement
362could shrink the interpreter structure; a size saving which is multiplied by
363the number of threads running.
364
fee0a0f7 365=head2 Profile Perl - am I hot or not?
62403a3c 366
fee0a0f7
NC
367The Perl source code is stable enough that it makes sense to profile it,
368identify and optimise the hotspots. It would be good to measure the
369performance of the Perl interpreter using free tools such as cachegrind,
370gprof, and dtrace, and work to reduce the bottlenecks they reveal.
371
372As part of this, the idea of F<pp_hot.c> is that it contains the I<hot> ops,
373the ops that are most commonly used. The idea is that by grouping them, their
374object code will be adjacent in the executable, so they have a greater chance
375of already being in the CPU cache (or swapped in) due to being near another op
376already in use.
62403a3c
NC
377
378Except that it's not clear if these really are the most commonly used ops. So
fee0a0f7
NC
379as part of exercising your skills with coverage and profiling tools you might
380want to determine what ops I<really> are the most commonly used. And in turn
381suggest evictions and promotions to achieve a better F<pp_hot.c>.
62403a3c 382
98fed0ad
NC
383=head2 Allocate OPs from arenas
384
385Currently all new OP structures are individually malloc()ed and free()d.
386All C<malloc> implementations have space overheads, and are now as fast as
387custom allocates so it would both use less memory and less CPU to allocate
388the various OP structures from arenas. The SV arena code can probably be
389re-used for this.
390
a229ae3b 391=head2 Improve win32/wince.c
0bdfc961 392
a229ae3b 393Currently, numerous functions look virtually, if not completely,
02f21748
RGS
394identical in both C<win32/wince.c> and C<win32/win32.c> files, which can't
395be good.
0bdfc961 396
0bdfc961 397=head1 Tasks that need a knowledge of XS
e50bb9a1 398
0bdfc961
NC
399These tasks would need C knowledge, and roughly the level of knowledge of
400the perl API that comes from writing modules that use XS to interface to
401C.
402
f23930d5 403=head2 shrink C<PVBM>s
4a750395 404
35b64ab6 405By removing unused elements and careful re-ordering, the structures for C<AV>s,
f23930d5
NC
406C<HV>s, C<CV>s and C<GV>s have recently been shrunk considerably. C<PVIO>s
407probably aren't worth it, as typical programs don't use more than 8, and
408(at least) C<Filter::Util::Call> uses C<SvPVX>/C<SvCUR>/C<SvLEN> on a C<PVIO>,
409so it would mean code changes to modules on CPAN. C<PVBM>s might have some
410savings to win.
4a750395 411
cd793d32 412=head2 autovivification
e50bb9a1 413
cd793d32 414Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict;
e50bb9a1 415
0bdfc961 416This task is incremental - even a little bit of work on it will help.
e50bb9a1 417
0bdfc961 418=head2 Unicode in Filenames
e50bb9a1 419
0bdfc961
NC
420chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open,
421opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen,
422system, truncate, unlink, utime, -X. All these could potentially accept
423Unicode filenames either as input or output (and in the case of system
424and qx Unicode in general, as input or output to/from the shell).
425Whether a filesystem - an operating system pair understands Unicode in
426filenames varies.
e50bb9a1 427
0bdfc961
NC
428Known combinations that have some level of understanding include
429Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac
430OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to
431create Unicode filenames, what forms of Unicode are accepted and used
432(UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used,
433and so on, varies. Finding the right level of interfacing to Perl
434requires some thought. Remember that an OS does not implicate a
435filesystem.
e50bb9a1 436
0bdfc961
NC
437(The Windows -C command flag "wide API support" has been at least
438temporarily retired in 5.8.1, and the -C has been repurposed, see
439L<perlrun>.)
969e704b 440
0bdfc961 441=head2 Unicode in %ENV
969e704b 442
0bdfc961 443Currently the %ENV entries are always byte strings.
e50bb9a1 444
0bdfc961 445=head2 use less 'memory'
e50bb9a1 446
0bdfc961
NC
447Investigate trade offs to switch out perl's choices on memory usage.
448Particularly perl should be able to give memory back.
e50bb9a1 449
0bdfc961 450This task is incremental - even a little bit of work on it will help.
0abe3f7c 451
0bdfc961 452=head2 Re-implement C<:unique> in a way that is actually thread-safe
0abe3f7c 453
0bdfc961
NC
454The old implementation made bad assumptions on several levels. A good 90%
455solution might be just to make C<:unique> work to share the string buffer
456of SvPVs. That way large constant strings can be shared between ithreads,
457such as the configuration information in F<Config>.
0abe3f7c 458
0bdfc961 459=head2 Make tainting consistent
0abe3f7c 460
0bdfc961
NC
461Tainting would be easier to use if it didn't take documented shortcuts and
462allow taint to "leak" everywhere within an expression.
0abe3f7c 463
0bdfc961 464=head2 readpipe(LIST)
0abe3f7c 465
0bdfc961
NC
466system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid
467running a shell. readpipe() (the function behind qx//) could be similarly
468extended.
0abe3f7c 469
d1307786 470=head2 strcat(), strcpy(), strncat(), strncpy(), sprintf(), vsprintf()
e50bb9a1 471
d1307786
JH
472Maybe create a utility that checks after each libperl.a creation that
473none of the above (nor sprintf(), vsprintf(), or *SHUDDER* gets())
474ever creep back to libperl.a.
e50bb9a1 475
d1307786 476 nm libperl.a | ./miniperl -alne '$o = $F[0] if /:$/; print "$o $F[1]" if $F[0] eq "U" && $F[1] =~ /^(?:strn?c(?:at|py)|v?sprintf|gets)$/'
e50bb9a1 477
d1307786
JH
478Note, of course, that this will only tell whether B<your> platform
479is using those naughty interfaces.
f86a8bc5 480
0bdfc961 481=head1 Tasks that need a knowledge of the interpreter
3298bd4d 482
0bdfc961
NC
483These tasks would need C knowledge, and knowledge of how the interpreter works,
484or a willingness to learn.
3298bd4d 485
d10fc472 486=head2 Attach/detach debugger from running program
1626a787 487
cd793d32
NC
488The old perltodo notes "With C<gdb>, you can attach the debugger to a running
489program if you pass the process ID. It would be good to do this with the Perl
0bdfc961
NC
490debugger on a running Perl program, although I'm not sure how it would be
491done." ssh and screen do this with named pipes in /tmp. Maybe we can too.
1626a787 492
0bdfc961
NC
493=head2 LVALUE functions for lists
494
495The old perltodo notes that lvalue functions don't work for list or hash
496slices. This would be good to fix.
497
498=head2 LVALUE functions in the debugger
499
500The old perltodo notes that lvalue functions don't work in the debugger. This
501would be good to fix.
502
0bdfc961
NC
503=head2 regexp optimiser optional
504
505The regexp optimiser is not optional. It should configurable to be, to allow
506its performance to be measured, and its bugs to be easily demonstrated.
507
02f21748
RGS
508=head2 delete &function
509
510Allow to delete functions. One can already undef them, but they're still
511in the stash.
512
513=head2 Make readpipe overridable
514
515so we can override qx// as well.
516
0bdfc961
NC
517=head2 optional optimizer
518
519Make the peephole optimizer optional. Currently it performs two tasks as
520it walks the optree - genuine peephole optimisations, and necessary fixups of
521ops. It would be good to find an efficient way to switch out the
522optimisations whilst keeping the fixups.
523
524=head2 You WANT *how* many
525
526Currently contexts are void, scalar and list. split has a special mechanism in
527place to pass in the number of return values wanted. It would be useful to
528have a general mechanism for this, backwards compatible and little speed hit.
529This would allow proposals such as short circuiting sort to be implemented
530as a module on CPAN.
531
532=head2 lexical aliases
533
534Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>.
535
536=head2 entersub XS vs Perl
537
538At the moment pp_entersub is huge, and has code to deal with entering both
539perl and XS subroutines. Subroutine implementations rarely change between
540perl and XS at run time, so investigate using 2 ops to enter subs (one for
541XS, one for perl) and swap between if a sub is redefined.
2810d901
NC
542
543=head2 Self ties
544
545self ties are currently illegal because they caused too many segfaults. Maybe
546the causes of these could be tracked down and self-ties on all types re-
547instated.
0bdfc961
NC
548
549=head2 Optimize away @_
550
551The old perltodo notes "Look at the "reification" code in C<av.c>".
552
0bdfc961
NC
553=head2 What hooks would assertions need?
554
555Assertions are in the core, and work. However, assertions needed to be added
556as a core patch, rather than an XS module in ext, or a CPAN module, because
557the core has no hooks in the necessary places. It would be useful to
558investigate what hooks would need to be added to make it possible to provide
559the full assertion support from a CPAN module, so that we aren't constraining
560the imagination of future CPAN authors.
561
16fc99ce
NC
562=head2 Properly Unicode safe tokeniser and pads.
563
564The tokeniser isn't actually very UTF-8 clean. C<use utf8;> is a hack -
565variable names are stored in stashes as raw bytes, without the utf-8 flag
566set. The pad API only takes a C<char *> pointer, so that's all bytes too. The
567tokeniser ignores the UTF-8-ness of C<PL_rsfp>, or any SVs returned from
568source filters. All this could be fixed.
569
0bdfc961
NC
570=head1 Big projects
571
572Tasks that will get your name mentioned in the description of the "Highlights
573of 5.10"
574
575=head2 make ithreads more robust
576
4e577f8b 577Generally make ithreads more robust. See also L</iCOW>
0bdfc961
NC
578
579This task is incremental - even a little bit of work on it will help, and
580will be greatly appreciated.
581
6c047da7
YST
582One bit would be to write the missing code in sv.c:Perl_dirp_dup.
583
0bdfc961
NC
584=head2 iCOW
585
586Sarathy and Arthur have a proposal for an improved Copy On Write which
587specifically will be able to COW new ithreads. If this can be implemented
588it would be a good thing.
589
590=head2 (?{...}) closures in regexps
591
592Fix (or rewrite) the implementation of the C</(?{...})/> closures.
593
594=head2 A re-entrant regexp engine
595
596This will allow the use of a regex from inside (?{ }), (??{ }) and
597(?(?{ })|) constructs.
6bda09f9 598
6bda09f9
YO
599=head2 Add (?YES) (?NO) to regexp enigne
600
601YES/NO would allow a subpattern to be passed/failed but allow backtracking.
602Basically a more efficient (?=), (?!).
603
604demerphq has this on his todo list
605
606=head2 Add (?SUCCEED) (?FAIL) to regexp engine
607
608SUCCEED/FAIL would allow a pattern to be passed/failed but without backtracking.
609Thus you could signal that a pattern has matched or not, and return (regardless
610that there is more pattern following).
611
612demerphq has this on his todo list
613
614=head2 Add (?CUT) (?COMMIT) to regexp engine
615
616CUT would allow a pattern to say "do not backtrack beyond here".
617COMMIT would say match from here or don't, but don't try the pattern from
618another starting pattern.
619
620These correspond to the \v and \V that Jeffrey Friedl mentions in
621Mastering Regular Expressions 2nd edition.
622
623demerphq has this on his todo list
624
625=head2 Add class set operations to regexp engine
626
627Apparently these are quite useful. Anyway, Jeffery Friedl wants them.
628
629demerphq has this on his todo list, but right at the bottom.
630
631