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1=head1 NAME
2
3perltodo - Perl TO-DO List
4
5=head1 DESCRIPTION
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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
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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
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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
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25The roadmap to 5.10 envisages feature based releases, as various items in this
26TODO are completed.
27
256ddcd0
YO
28=head2 Needed for the final 5.10.0 release
29
256ddcd0
YO
30Review perlguts. Significant changes have occured since 5.8, and we can't
31release a new version without making sure these are covered.
32
0bdfc961 33=head1 Tasks that only need Perl knowledge
e50bb9a1 34
0bdfc961 35=head2 common test code for timed bail out
e50bb9a1 36
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37Write portable self destruct code for tests to stop them burning CPU in
38infinite loops. This needs to avoid using alarm, as some of the tests are
39testing alarm/sleep or timers.
e50bb9a1 40
87a942b1 41=head2 POD -E<gt> HTML conversion in the core still sucks
e50bb9a1 42
938c8732 43Which is crazy given just how simple POD purports to be, and how simple HTML
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44can be. It's not actually I<as> simple as it sounds, particularly with the
45flexibility POD allows for C<=item>, but it would be good to improve the
46visual appeal of the HTML generated, and to avoid it having any validation
47errors. See also L</make HTML install work>, as the layout of installation tree
48is needed to improve the cross-linking.
938c8732 49
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50The addition of C<Pod::Simple> and its related modules may make this task
51easier to complete.
52
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53=head2 Parallel testing
54
b2e2905c 55(This probably impacts much more than the core: also the Test::Harness
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56and TAP::* modules on CPAN.)
57
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58The core regression test suite is getting ever more comprehensive, which has
59the side effect that it takes longer to run. This isn't so good. Investigate
60whether it would be feasible to give the harness script the B<option> of
61running sets of tests in parallel. This would be useful for tests in
62F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>.
63
64Questions to answer
65
66=over 4
67
68=item 1
69
70How does screen layout work when you're running more than one test?
71
72=item 2
73
74How does the caller of test specify how many tests to run in parallel?
75
76=item 3
77
78How do setup/teardown tests identify themselves?
79
80=back
81
82Pugs already does parallel testing - can their approach be re-used?
83
0bdfc961 84=head2 Make Schwern poorer
e50bb9a1 85
613bd4f7 86We should have tests for everything. When all the core's modules are tested,
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87Schwern has promised to donate to $500 to TPF. We may need volunteers to
88hold him upside down and shake vigorously in order to actually extract the
89cash.
3958b146 90
0bdfc961 91=head2 Improve the coverage of the core tests
e50bb9a1 92
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93Use Devel::Cover to ascertain the core modules's test coverage, then add
94tests that are currently missing.
30222c0f 95
0bdfc961 96=head2 test B
e50bb9a1 97
0bdfc961 98A full test suite for the B module would be nice.
e50bb9a1 99
0bdfc961 100=head2 A decent benchmark
e50bb9a1 101
617eabfa 102C<perlbench> seems impervious to any recent changes made to the perl core. It
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103would be useful to have a reasonable general benchmarking suite that roughly
104represented what current perl programs do, and measurably reported whether
105tweaks to the core improve, degrade or don't really affect performance, to
106guide people attempting to optimise the guts of perl. Gisle would welcome
107new tests for perlbench.
6168cf99 108
0bdfc961 109=head2 fix tainting bugs
6168cf99 110
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111Fix the bugs revealed by running the test suite with the C<-t> switch (via
112C<make test.taintwarn>).
e50bb9a1 113
0bdfc961 114=head2 Dual life everything
e50bb9a1 115
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116As part of the "dists" plan, anything that doesn't belong in the smallest perl
117distribution needs to be dual lifed. Anything else can be too. Figure out what
118changes would be needed to package that module and its tests up for CPAN, and
119do so. Test it with older perl releases, and fix the problems you find.
e50bb9a1 120
0bdfc961 121=head2 Improving C<threads::shared>
722d2a37 122
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123Investigate whether C<threads::shared> could share aggregates properly with
124only Perl level changes to shared.pm
722d2a37 125
0bdfc961 126=head2 POSIX memory footprint
e50bb9a1 127
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128Ilya observed that use POSIX; eats memory like there's no tomorrow, and at
129various times worked to cut it down. There is probably still fat to cut out -
130for example POSIX passes Exporter some very memory hungry data structures.
e50bb9a1 131
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132=head2 embed.pl/makedef.pl
133
134There is a script F<embed.pl> that generates several header files to prefix
135all of Perl's symbols in a consistent way, to provide some semblance of
136namespace support in C<C>. Functions are declared in F<embed.fnc>, variables
907b3e23 137in F<interpvar.h>. Quite a few of the functions and variables
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138are conditionally declared there, using C<#ifdef>. However, F<embed.pl>
139doesn't understand the C macros, so the rules about which symbols are present
140when is duplicated in F<makedef.pl>. Writing things twice is bad, m'kay.
141It would be good to teach C<embed.pl> to understand the conditional
142compilation, and hence remove the duplication, and the mistakes it has caused.
e50bb9a1 143
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144=head2 use strict; and AutoLoad
145
146Currently if you write
147
148 package Whack;
149 use AutoLoader 'AUTOLOAD';
150 use strict;
151 1;
152 __END__
153 sub bloop {
154 print join (' ', No, strict, here), "!\n";
155 }
156
157then C<use strict;> isn't in force within the autoloaded subroutines. It would
158be more consistent (and less surprising) to arrange for all lexical pragmas
159in force at the __END__ block to be in force within each autoloaded subroutine.
160
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161There's a similar problem with SelfLoader.
162
0bdfc961 163=head1 Tasks that need a little sysadmin-type knowledge
e50bb9a1 164
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165Or if you prefer, tasks that you would learn from, and broaden your skills
166base...
e50bb9a1 167
cd793d32 168=head2 make HTML install work
e50bb9a1 169
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170There is an C<installhtml> target in the Makefile. It's marked as
171"experimental". It would be good to get this tested, make it work reliably, and
172remove the "experimental" tag. This would include
173
174=over 4
175
176=item 1
177
178Checking that cross linking between various parts of the documentation works.
179In particular that links work between the modules (files with POD in F<lib/>)
180and the core documentation (files in F<pod/>)
181
182=item 2
183
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184Work out how to split C<perlfunc> into chunks, preferably one per function
185group, preferably with general case code that could be used elsewhere.
186Challenges here are correctly identifying the groups of functions that go
187together, and making the right named external cross-links point to the right
188page. Things to be aware of are C<-X>, groups such as C<getpwnam> to
189C<endservent>, two or more C<=items> giving the different parameter lists, such
190as
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191
192 =item substr EXPR,OFFSET,LENGTH,REPLACEMENT
adebf063 193 =item substr EXPR,OFFSET,LENGTH
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194 =item substr EXPR,OFFSET
195
196and different parameter lists having different meanings. (eg C<select>)
197
198=back
3a89a73c 199
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200=head2 compressed man pages
201
202Be able to install them. This would probably need a configure test to see how
203the system does compressed man pages (same directory/different directory?
204same filename/different filename), as well as tweaking the F<installman> script
205to compress as necessary.
206
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207=head2 Add a code coverage target to the Makefile
208
209Make it easy for anyone to run Devel::Cover on the core's tests. The steps
210to do this manually are roughly
211
212=over 4
213
214=item *
215
216do a normal C<Configure>, but include Devel::Cover as a module to install
217(see F<INSTALL> for how to do this)
218
219=item *
220
221 make perl
222
223=item *
224
225 cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness
226
227=item *
228
229Process the resulting Devel::Cover database
230
231=back
232
233This just give you the coverage of the F<.pm>s. To also get the C level
234coverage you need to
235
236=over 4
237
238=item *
239
240Additionally tell C<Configure> to use the appropriate C compiler flags for
241C<gcov>
242
243=item *
244
245 make perl.gcov
246
247(instead of C<make perl>)
248
249=item *
250
251After running the tests run C<gcov> to generate all the F<.gcov> files.
252(Including down in the subdirectories of F<ext/>
253
254=item *
255
256(From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files
257to get their stats into the cover_db directory.
258
259=item *
260
261Then process the Devel::Cover database
262
263=back
264
265It would be good to add a single switch to C<Configure> to specify that you
266wanted to perform perl level coverage, and another to specify C level
267coverage, and have C<Configure> and the F<Makefile> do all the right things
268automatically.
269
02f21748 270=head2 Make Config.pm cope with differences between built and installed perl
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271
272Quite often vendors ship a perl binary compiled with their (pay-for)
273compilers. People install a free compiler, such as gcc. To work out how to
274build extensions, Perl interrogates C<%Config>, so in this situation
275C<%Config> describes compilers that aren't there, and extension building
276fails. This forces people into choosing between re-compiling perl themselves
277using the compiler they have, or only using modules that the vendor ships.
278
279It would be good to find a way teach C<Config.pm> about the installation setup,
280possibly involving probing at install time or later, so that the C<%Config> in
281a binary distribution better describes the installed machine, when the
282installed machine differs from the build machine in some significant way.
283
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284=head2 linker specification files
285
286Some platforms mandate that you provide a list of a shared library's external
287symbols to the linker, so the core already has the infrastructure in place to
288do this for generating shared perl libraries. My understanding is that the
289GNU toolchain can accept an optional linker specification file, and restrict
290visibility just to symbols declared in that file. It would be good to extend
291F<makedef.pl> to support this format, and to provide a means within
292C<Configure> to enable it. This would allow Unix users to test that the
293export list is correct, and to build a perl that does not pollute the global
294namespace with private symbols.
295
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296=head2 Cross-compile support
297
298Currently C<Configure> understands C<-Dusecrosscompile> option. This option
299arranges for building C<miniperl> for TARGET machine, so this C<miniperl> is
300assumed then to be copied to TARGET machine and used as a replacement of full
301C<perl> executable.
302
d1307786 303This could be done little differently. Namely C<miniperl> should be built for
a229ae3b 304HOST and then full C<perl> with extensions should be compiled for TARGET.
d1307786 305This, however, might require extra trickery for %Config: we have one config
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306first for HOST and then another for TARGET. Tools like MakeMaker will be
307mightily confused. Having around two different types of executables and
308libraries (HOST and TARGET) makes life interesting for Makefiles and
309shell (and Perl) scripts. There is $Config{run}, normally empty, which
310can be used as an execution wrapper. Also note that in some
311cross-compilation/execution environments the HOST and the TARGET do
312not see the same filesystem(s), the $Config{run} may need to do some
313file/directory copying back and forth.
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314
315=head1 Tasks that need a little C knowledge
316
317These tasks would need a little C knowledge, but don't need any specific
318background or experience with XS, or how the Perl interpreter works
319
320=head2 Make it clear from -v if this is the exact official release
89007cb3 321
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322Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that
323usually defines one local patch, of the form "MAINT12345" or "RC1". The output
324of perl -v doesn't report that a perl isn't an official release, and this
89007cb3 325information can get lost in bugs reports. Because of this, the minor version
fa11829f 326isn't bumped up until RC time, to minimise the possibility of versions of perl
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327escaping that believe themselves to be newer than they actually are.
328
329It would be useful to find an elegant way to have the "this is an interim
330maintenance release" or "this is a release candidate" in the terse -v output,
331and have it so that it's easy for the pumpking to remove this just as the
332release tarball is rolled up. This way the version pulled out of rsync would
333always say "I'm a development release" and it would be safe to bump the
334reported minor version as soon as a release ships, which would aid perl
335developers.
336
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337This task is really about thinking of an elegant way to arrange the C source
338such that it's trivial for the Pumpking to flag "this is an official release"
339when making a tarball, yet leave the default source saying "I'm not the
340official release".
341
fee0a0f7 342=head2 Profile Perl - am I hot or not?
62403a3c 343
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344The Perl source code is stable enough that it makes sense to profile it,
345identify and optimise the hotspots. It would be good to measure the
346performance of the Perl interpreter using free tools such as cachegrind,
347gprof, and dtrace, and work to reduce the bottlenecks they reveal.
348
349As part of this, the idea of F<pp_hot.c> is that it contains the I<hot> ops,
350the ops that are most commonly used. The idea is that by grouping them, their
351object code will be adjacent in the executable, so they have a greater chance
352of already being in the CPU cache (or swapped in) due to being near another op
353already in use.
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354
355Except that it's not clear if these really are the most commonly used ops. So
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356as part of exercising your skills with coverage and profiling tools you might
357want to determine what ops I<really> are the most commonly used. And in turn
358suggest evictions and promotions to achieve a better F<pp_hot.c>.
62403a3c 359
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360=head2 Allocate OPs from arenas
361
362Currently all new OP structures are individually malloc()ed and free()d.
363All C<malloc> implementations have space overheads, and are now as fast as
364custom allocates so it would both use less memory and less CPU to allocate
365the various OP structures from arenas. The SV arena code can probably be
366re-used for this.
367
a229ae3b 368=head2 Improve win32/wince.c
0bdfc961 369
a229ae3b 370Currently, numerous functions look virtually, if not completely,
02f21748 371identical in both C<win32/wince.c> and C<win32/win32.c> files, which can't
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372be good.
373
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374=head2 Use secure CRT functions when building with VC8 on Win32
375
376Visual C++ 2005 (VC++ 8.x) deprecated a number of CRT functions on the basis
377that they were "unsafe" and introduced differently named secure versions of
378them as replacements, e.g. instead of writing
379
380 FILE* f = fopen(__FILE__, "r");
381
382one should now write
383
384 FILE* f;
385 errno_t err = fopen_s(&f, __FILE__, "r");
386
387Currently, the warnings about these deprecations have been disabled by adding
388-D_CRT_SECURE_NO_DEPRECATE to the CFLAGS. It would be nice to remove that
389warning suppressant and actually make use of the new secure CRT functions.
390
391There is also a similar issue with POSIX CRT function names like fileno having
392been deprecated in favour of ISO C++ conformant names like _fileno. These
393warnings are also currently suppressed with the compiler option /wd4996. It
394might be nice to do as Microsoft suggest here too, although, unlike the secure
395functions issue, there is presumably little or no benefit in this case.
396
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397=head1 Tasks that need a knowledge of XS
398
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
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403=head2 autovivification
404
405Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict;
406
407This task is incremental - even a little bit of work on it will help.
408
409=head2 Unicode in Filenames
410
411chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open,
412opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen,
413system, truncate, unlink, utime, -X. All these could potentially accept
414Unicode filenames either as input or output (and in the case of system
415and qx Unicode in general, as input or output to/from the shell).
416Whether a filesystem - an operating system pair understands Unicode in
417filenames varies.
418
419Known combinations that have some level of understanding include
420Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac
421OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to
422create Unicode filenames, what forms of Unicode are accepted and used
423(UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used,
424and so on, varies. Finding the right level of interfacing to Perl
425requires some thought. Remember that an OS does not implicate a
426filesystem.
427
428(The Windows -C command flag "wide API support" has been at least
429temporarily retired in 5.8.1, and the -C has been repurposed, see
430L<perlrun>.)
431
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432Most probably the right way to do this would be this:
433L</"Virtualize operating system access">.
434
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435=head2 Unicode in %ENV
436
437Currently the %ENV entries are always byte strings.
87a942b1 438See L</"Virtualize operating system access">.
6d71adcd 439
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440=head2 Unicode and glob()
441
442Currently glob patterns and filenames returned from File::Glob::glob()
87a942b1 443are always byte strings. See L</"Virtualize operating system access">.
1f2e7916 444
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445=head2 use less 'memory'
446
447Investigate trade offs to switch out perl's choices on memory usage.
448Particularly perl should be able to give memory back.
449
450This task is incremental - even a little bit of work on it will help.
451
452=head2 Re-implement C<:unique> in a way that is actually thread-safe
453
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>.
458
459=head2 Make tainting consistent
460
461Tainting would be easier to use if it didn't take documented shortcuts and
462allow taint to "leak" everywhere within an expression.
463
464=head2 readpipe(LIST)
465
466system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid
467running a shell. readpipe() (the function behind qx//) could be similarly
468extended.
469
470=head2 strcat(), strcpy(), strncat(), strncpy(), sprintf(), vsprintf()
471
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.
475
476 nm libperl.a | ./miniperl -alne '$o = $F[0] if /:$/; print "$o $F[1]" if $F[0] eq "U" && $F[1] =~ /^(?:strn?c(?:at|py)|v?sprintf|gets)$/'
477
478Note, of course, that this will only tell whether B<your> platform
479is using those naughty interfaces.
480
481=head2 Audit the code for destruction ordering assumptions
482
483Change 25773 notes
484
485 /* Need to check SvMAGICAL, as during global destruction it may be that
486 AvARYLEN(av) has been freed before av, and hence the SvANY() pointer
487 is now part of the linked list of SV heads, rather than pointing to
488 the original body. */
489 /* FIXME - audit the code for other bugs like this one. */
490
491adding the C<SvMAGICAL> check to
492
493 if (AvARYLEN(av) && SvMAGICAL(AvARYLEN(av))) {
494 MAGIC *mg = mg_find (AvARYLEN(av), PERL_MAGIC_arylen);
495
496Go through the core and look for similar assumptions that SVs have particular
497types, as all bets are off during global destruction.
498
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499=head2 Extend PerlIO and PerlIO::Scalar
500
501PerlIO::Scalar doesn't know how to truncate(). Implementing this
502would require extending the PerlIO vtable.
503
504Similarly the PerlIO vtable doesn't know about formats (write()), or
505about stat(), or chmod()/chown(), utime(), or flock().
506
507(For PerlIO::Scalar it's hard to see what e.g. mode bits or ownership
508would mean.)
509
510PerlIO doesn't do directories or symlinks, either: mkdir(), rmdir(),
511opendir(), closedir(), seekdir(), rewinddir(), glob(); symlink(),
512readlink().
513
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514=head2 -C on the #! line
515
516It should be possible to make -C work correctly if found on the #! line,
517given that all perl command line options are strict ASCII, and -C changes
518only the interpretation of non-ASCII characters, and not for the script file
519handle. To make it work needs some investigation of the ordering of function
520calls during startup, and (by implication) a bit of tweaking of that order.
521
522
0bdfc961 523=head1 Tasks that need a knowledge of the interpreter
3298bd4d 524
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525These tasks would need C knowledge, and knowledge of how the interpreter works,
526or a willingness to learn.
3298bd4d 527
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528=head2 Implement $value ~~ 0 .. $range
529
530It would be nice to extend the syntax of the C<~~> operator to also
531understand numeric (and maybe alphanumeric) ranges.
532
d10fc472 533=head2 Attach/detach debugger from running program
1626a787 534
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535The old perltodo notes "With C<gdb>, you can attach the debugger to a running
536program if you pass the process ID. It would be good to do this with the Perl
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537debugger on a running Perl program, although I'm not sure how it would be
538done." ssh and screen do this with named pipes in /tmp. Maybe we can too.
1626a787 539
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540=head2 LVALUE functions for lists
541
542The old perltodo notes that lvalue functions don't work for list or hash
543slices. This would be good to fix.
544
545=head2 LVALUE functions in the debugger
546
547The old perltodo notes that lvalue functions don't work in the debugger. This
548would be good to fix.
549
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550=head2 regexp optimiser optional
551
552The regexp optimiser is not optional. It should configurable to be, to allow
553its performance to be measured, and its bugs to be easily demonstrated.
554
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555=head2 delete &function
556
557Allow to delete functions. One can already undef them, but they're still
558in the stash.
559
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560=head2 C</w> regex modifier
561
562That flag would enable to match whole words, and also to interpolate
563arrays as alternations. With it, C</P/w> would be roughly equivalent to:
564
565 do { local $"='|'; /\b(?:P)\b/ }
566
567See L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-01/msg00400.html>
568for the discussion.
569
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570=head2 optional optimizer
571
572Make the peephole optimizer optional. Currently it performs two tasks as
573it walks the optree - genuine peephole optimisations, and necessary fixups of
574ops. It would be good to find an efficient way to switch out the
575optimisations whilst keeping the fixups.
576
577=head2 You WANT *how* many
578
579Currently contexts are void, scalar and list. split has a special mechanism in
580place to pass in the number of return values wanted. It would be useful to
581have a general mechanism for this, backwards compatible and little speed hit.
582This would allow proposals such as short circuiting sort to be implemented
583as a module on CPAN.
584
585=head2 lexical aliases
586
587Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>.
588
589=head2 entersub XS vs Perl
590
591At the moment pp_entersub is huge, and has code to deal with entering both
592perl and XS subroutines. Subroutine implementations rarely change between
593perl and XS at run time, so investigate using 2 ops to enter subs (one for
594XS, one for perl) and swap between if a sub is redefined.
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595
596=head2 Self ties
597
598self ties are currently illegal because they caused too many segfaults. Maybe
599the causes of these could be tracked down and self-ties on all types re-
600instated.
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601
602=head2 Optimize away @_
603
604The old perltodo notes "Look at the "reification" code in C<av.c>".
605
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606=head2 Properly Unicode safe tokeniser and pads.
607
608The tokeniser isn't actually very UTF-8 clean. C<use utf8;> is a hack -
609variable names are stored in stashes as raw bytes, without the utf-8 flag
610set. The pad API only takes a C<char *> pointer, so that's all bytes too. The
611tokeniser ignores the UTF-8-ness of C<PL_rsfp>, or any SVs returned from
612source filters. All this could be fixed.
613
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614=head2 The yada yada yada operators
615
616Perl 6's Synopsis 3 says:
617
618I<The ... operator is the "yada, yada, yada" list operator, which is used as
619the body in function prototypes. It complains bitterly (by calling fail)
620if it is ever executed. Variant ??? calls warn, and !!! calls die.>
621
622Those would be nice to add to Perl 5. That could be done without new ops.
623
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624=head2 Virtualize operating system access
625
626Implement a set of "vtables" that virtualizes operating system access
627(open(), mkdir(), unlink(), readdir(), getenv(), etc.) At the very
628least these interfaces should take SVs as "name" arguments instead of
629bare char pointers; probably the most flexible and extensible way
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630would be for the Perl-facing interfaces to accept HVs. The system
631needs to be per-operating-system and per-file-system
632hookable/filterable, preferably both from XS and Perl level
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633(L<perlport/"Files and Filesystems"> is good reading at this point,
634in fact, all of L<perlport> is.)
635
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636This has actually already been implemented (but only for Win32),
637take a look at F<iperlsys.h> and F<win32/perlhost.h>. While all Win32
638variants go through a set of "vtables" for operating system access,
639non-Win32 systems currently go straight for the POSIX/UNIX-style
640system/library call. Similar system as for Win32 should be
641implemented for all platforms. The existing Win32 implementation
642probably does not need to survive alongside this proposed new
643implementation, the approaches could be merged.
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644
645What would this give us? One often-asked-for feature this would
646enable is using Unicode for filenames (and other "names" like %ENV,
647usernames, hostnames, and so forth.) But this would also allow for
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648things like virtual filesystems, virtual networks, and "sandboxes"
649(though as long as dynamic loading of random object code is allowed,
650not very safe sandboxes since external code of course know not of
651Perl's vtables). An example of a smaller "sandbox" is that this
652feature can be used to implement per-thread working directories:
653Win32 already does this.
87a942b1 654
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655=head1 Big projects
656
657Tasks that will get your name mentioned in the description of the "Highlights
87a942b1 658of 5.12"
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659
660=head2 make ithreads more robust
661
4e577f8b 662Generally make ithreads more robust. See also L</iCOW>
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663
664This task is incremental - even a little bit of work on it will help, and
665will be greatly appreciated.
666
6c047da7
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667One bit would be to write the missing code in sv.c:Perl_dirp_dup.
668
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669Fix Perl_sv_dup, et al so that threads can return objects.
670
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671=head2 iCOW
672
673Sarathy and Arthur have a proposal for an improved Copy On Write which
674specifically will be able to COW new ithreads. If this can be implemented
675it would be a good thing.
676
677=head2 (?{...}) closures in regexps
678
679Fix (or rewrite) the implementation of the C</(?{...})/> closures.
680
681=head2 A re-entrant regexp engine
682
683This will allow the use of a regex from inside (?{ }), (??{ }) and
684(?(?{ })|) constructs.
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686=head2 Add class set operations to regexp engine
687
688Apparently these are quite useful. Anyway, Jeffery Friedl wants them.
689
690demerphq has this on his todo list, but right at the bottom.