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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
0bdfc961 23=head1 Tasks that only need Perl knowledge
e50bb9a1 24
0bdfc961 25=head2 common test code for timed bail out
e50bb9a1 26
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27Write portable self destruct code for tests to stop them burning CPU in
28infinite loops. This needs to avoid using alarm, as some of the tests are
29testing alarm/sleep or timers.
e50bb9a1 30
87a942b1 31=head2 POD -E<gt> HTML conversion in the core still sucks
e50bb9a1 32
938c8732 33Which is crazy given just how simple POD purports to be, and how simple HTML
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34can be. It's not actually I<as> simple as it sounds, particularly with the
35flexibility POD allows for C<=item>, but it would be good to improve the
36visual appeal of the HTML generated, and to avoid it having any validation
37errors. See also L</make HTML install work>, as the layout of installation tree
38is needed to improve the cross-linking.
938c8732 39
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40The addition of C<Pod::Simple> and its related modules may make this task
41easier to complete.
42
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43=head2 Parallel testing
44
b2e2905c 45(This probably impacts much more than the core: also the Test::Harness
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46and TAP::* modules on CPAN.)
47
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48The core regression test suite is getting ever more comprehensive, which has
49the side effect that it takes longer to run. This isn't so good. Investigate
50whether it would be feasible to give the harness script the B<option> of
51running sets of tests in parallel. This would be useful for tests in
52F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>.
53
54Questions to answer
55
56=over 4
57
58=item 1
59
60How does screen layout work when you're running more than one test?
61
62=item 2
63
64How does the caller of test specify how many tests to run in parallel?
65
66=item 3
67
68How do setup/teardown tests identify themselves?
69
70=back
71
72Pugs already does parallel testing - can their approach be re-used?
73
0bdfc961 74=head2 Make Schwern poorer
e50bb9a1 75
613bd4f7 76We should have tests for everything. When all the core's modules are tested,
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77Schwern has promised to donate to $500 to TPF. We may need volunteers to
78hold him upside down and shake vigorously in order to actually extract the
79cash.
3958b146 80
0bdfc961 81=head2 Improve the coverage of the core tests
e50bb9a1 82
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83Use Devel::Cover to ascertain the core modules's test coverage, then add
84tests that are currently missing.
30222c0f 85
0bdfc961 86=head2 test B
e50bb9a1 87
0bdfc961 88A full test suite for the B module would be nice.
e50bb9a1 89
0bdfc961 90=head2 A decent benchmark
e50bb9a1 91
617eabfa 92C<perlbench> seems impervious to any recent changes made to the perl core. It
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93would be useful to have a reasonable general benchmarking suite that roughly
94represented what current perl programs do, and measurably reported whether
95tweaks to the core improve, degrade or don't really affect performance, to
96guide people attempting to optimise the guts of perl. Gisle would welcome
97new tests for perlbench.
6168cf99 98
0bdfc961 99=head2 fix tainting bugs
6168cf99 100
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101Fix the bugs revealed by running the test suite with the C<-t> switch (via
102C<make test.taintwarn>).
e50bb9a1 103
0bdfc961 104=head2 Dual life everything
e50bb9a1 105
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106As part of the "dists" plan, anything that doesn't belong in the smallest perl
107distribution needs to be dual lifed. Anything else can be too. Figure out what
108changes would be needed to package that module and its tests up for CPAN, and
109do so. Test it with older perl releases, and fix the problems you find.
e50bb9a1 110
0bdfc961 111=head2 Improving C<threads::shared>
722d2a37 112
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113Investigate whether C<threads::shared> could share aggregates properly with
114only Perl level changes to shared.pm
722d2a37 115
0bdfc961 116=head2 POSIX memory footprint
e50bb9a1 117
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118Ilya observed that use POSIX; eats memory like there's no tomorrow, and at
119various times worked to cut it down. There is probably still fat to cut out -
120for example POSIX passes Exporter some very memory hungry data structures.
e50bb9a1 121
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122=head2 embed.pl/makedef.pl
123
124There is a script F<embed.pl> that generates several header files to prefix
125all of Perl's symbols in a consistent way, to provide some semblance of
126namespace support in C<C>. Functions are declared in F<embed.fnc>, variables
907b3e23 127in F<interpvar.h>. Quite a few of the functions and variables
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128are conditionally declared there, using C<#ifdef>. However, F<embed.pl>
129doesn't understand the C macros, so the rules about which symbols are present
130when is duplicated in F<makedef.pl>. Writing things twice is bad, m'kay.
131It would be good to teach C<embed.pl> to understand the conditional
132compilation, and hence remove the duplication, and the mistakes it has caused.
e50bb9a1 133
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134=head2 use strict; and AutoLoad
135
136Currently if you write
137
138 package Whack;
139 use AutoLoader 'AUTOLOAD';
140 use strict;
141 1;
142 __END__
143 sub bloop {
144 print join (' ', No, strict, here), "!\n";
145 }
146
147then C<use strict;> isn't in force within the autoloaded subroutines. It would
148be more consistent (and less surprising) to arrange for all lexical pragmas
149in force at the __END__ block to be in force within each autoloaded subroutine.
150
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151There's a similar problem with SelfLoader.
152
0bdfc961 153=head1 Tasks that need a little sysadmin-type knowledge
e50bb9a1 154
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155Or if you prefer, tasks that you would learn from, and broaden your skills
156base...
e50bb9a1 157
cd793d32 158=head2 make HTML install work
e50bb9a1 159
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160There is an C<installhtml> target in the Makefile. It's marked as
161"experimental". It would be good to get this tested, make it work reliably, and
162remove the "experimental" tag. This would include
163
164=over 4
165
166=item 1
167
168Checking that cross linking between various parts of the documentation works.
169In particular that links work between the modules (files with POD in F<lib/>)
170and the core documentation (files in F<pod/>)
171
172=item 2
173
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174Work out how to split C<perlfunc> into chunks, preferably one per function
175group, preferably with general case code that could be used elsewhere.
176Challenges here are correctly identifying the groups of functions that go
177together, and making the right named external cross-links point to the right
178page. Things to be aware of are C<-X>, groups such as C<getpwnam> to
179C<endservent>, two or more C<=items> giving the different parameter lists, such
180as
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181
182 =item substr EXPR,OFFSET,LENGTH,REPLACEMENT
adebf063 183 =item substr EXPR,OFFSET,LENGTH
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184 =item substr EXPR,OFFSET
185
186and different parameter lists having different meanings. (eg C<select>)
187
188=back
3a89a73c 189
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190=head2 compressed man pages
191
192Be able to install them. This would probably need a configure test to see how
193the system does compressed man pages (same directory/different directory?
194same filename/different filename), as well as tweaking the F<installman> script
195to compress as necessary.
196
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197=head2 Add a code coverage target to the Makefile
198
199Make it easy for anyone to run Devel::Cover on the core's tests. The steps
200to do this manually are roughly
201
202=over 4
203
204=item *
205
206do a normal C<Configure>, but include Devel::Cover as a module to install
207(see F<INSTALL> for how to do this)
208
209=item *
210
211 make perl
212
213=item *
214
215 cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness
216
217=item *
218
219Process the resulting Devel::Cover database
220
221=back
222
223This just give you the coverage of the F<.pm>s. To also get the C level
224coverage you need to
225
226=over 4
227
228=item *
229
230Additionally tell C<Configure> to use the appropriate C compiler flags for
231C<gcov>
232
233=item *
234
235 make perl.gcov
236
237(instead of C<make perl>)
238
239=item *
240
241After running the tests run C<gcov> to generate all the F<.gcov> files.
242(Including down in the subdirectories of F<ext/>
243
244=item *
245
246(From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files
247to get their stats into the cover_db directory.
248
249=item *
250
251Then process the Devel::Cover database
252
253=back
254
255It would be good to add a single switch to C<Configure> to specify that you
256wanted to perform perl level coverage, and another to specify C level
257coverage, and have C<Configure> and the F<Makefile> do all the right things
258automatically.
259
02f21748 260=head2 Make Config.pm cope with differences between built and installed perl
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261
262Quite often vendors ship a perl binary compiled with their (pay-for)
263compilers. People install a free compiler, such as gcc. To work out how to
264build extensions, Perl interrogates C<%Config>, so in this situation
265C<%Config> describes compilers that aren't there, and extension building
266fails. This forces people into choosing between re-compiling perl themselves
267using the compiler they have, or only using modules that the vendor ships.
268
269It would be good to find a way teach C<Config.pm> about the installation setup,
270possibly involving probing at install time or later, so that the C<%Config> in
271a binary distribution better describes the installed machine, when the
272installed machine differs from the build machine in some significant way.
273
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274=head2 linker specification files
275
276Some platforms mandate that you provide a list of a shared library's external
277symbols to the linker, so the core already has the infrastructure in place to
278do this for generating shared perl libraries. My understanding is that the
279GNU toolchain can accept an optional linker specification file, and restrict
280visibility just to symbols declared in that file. It would be good to extend
281F<makedef.pl> to support this format, and to provide a means within
282C<Configure> to enable it. This would allow Unix users to test that the
283export list is correct, and to build a perl that does not pollute the global
284namespace with private symbols.
285
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286=head2 Cross-compile support
287
288Currently C<Configure> understands C<-Dusecrosscompile> option. This option
289arranges for building C<miniperl> for TARGET machine, so this C<miniperl> is
290assumed then to be copied to TARGET machine and used as a replacement of full
291C<perl> executable.
292
d1307786 293This could be done little differently. Namely C<miniperl> should be built for
a229ae3b 294HOST and then full C<perl> with extensions should be compiled for TARGET.
d1307786 295This, however, might require extra trickery for %Config: we have one config
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296first for HOST and then another for TARGET. Tools like MakeMaker will be
297mightily confused. Having around two different types of executables and
298libraries (HOST and TARGET) makes life interesting for Makefiles and
299shell (and Perl) scripts. There is $Config{run}, normally empty, which
300can be used as an execution wrapper. Also note that in some
301cross-compilation/execution environments the HOST and the TARGET do
302not see the same filesystem(s), the $Config{run} may need to do some
303file/directory copying back and forth.
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304
305=head1 Tasks that need a little C knowledge
306
307These tasks would need a little C knowledge, but don't need any specific
308background or experience with XS, or how the Perl interpreter works
309
310=head2 Make it clear from -v if this is the exact official release
89007cb3 311
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312Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that
313usually defines one local patch, of the form "MAINT12345" or "RC1". The output
314of perl -v doesn't report that a perl isn't an official release, and this
89007cb3 315information can get lost in bugs reports. Because of this, the minor version
fa11829f 316isn't bumped up until RC time, to minimise the possibility of versions of perl
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317escaping that believe themselves to be newer than they actually are.
318
319It would be useful to find an elegant way to have the "this is an interim
320maintenance release" or "this is a release candidate" in the terse -v output,
321and have it so that it's easy for the pumpking to remove this just as the
322release tarball is rolled up. This way the version pulled out of rsync would
323always say "I'm a development release" and it would be safe to bump the
324reported minor version as soon as a release ships, which would aid perl
325developers.
326
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327This task is really about thinking of an elegant way to arrange the C source
328such that it's trivial for the Pumpking to flag "this is an official release"
329when making a tarball, yet leave the default source saying "I'm not the
330official release".
331
fee0a0f7 332=head2 Profile Perl - am I hot or not?
62403a3c 333
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334The Perl source code is stable enough that it makes sense to profile it,
335identify and optimise the hotspots. It would be good to measure the
336performance of the Perl interpreter using free tools such as cachegrind,
337gprof, and dtrace, and work to reduce the bottlenecks they reveal.
338
339As part of this, the idea of F<pp_hot.c> is that it contains the I<hot> ops,
340the ops that are most commonly used. The idea is that by grouping them, their
341object code will be adjacent in the executable, so they have a greater chance
342of already being in the CPU cache (or swapped in) due to being near another op
343already in use.
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344
345Except that it's not clear if these really are the most commonly used ops. So
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346as part of exercising your skills with coverage and profiling tools you might
347want to determine what ops I<really> are the most commonly used. And in turn
348suggest evictions and promotions to achieve a better F<pp_hot.c>.
62403a3c 349
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350=head2 Allocate OPs from arenas
351
352Currently all new OP structures are individually malloc()ed and free()d.
353All C<malloc> implementations have space overheads, and are now as fast as
354custom allocates so it would both use less memory and less CPU to allocate
355the various OP structures from arenas. The SV arena code can probably be
356re-used for this.
357
a229ae3b 358=head2 Improve win32/wince.c
0bdfc961 359
a229ae3b 360Currently, numerous functions look virtually, if not completely,
02f21748 361identical in both C<win32/wince.c> and C<win32/win32.c> files, which can't
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362be good.
363
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364=head2 Use secure CRT functions when building with VC8 on Win32
365
366Visual C++ 2005 (VC++ 8.x) deprecated a number of CRT functions on the basis
367that they were "unsafe" and introduced differently named secure versions of
368them as replacements, e.g. instead of writing
369
370 FILE* f = fopen(__FILE__, "r");
371
372one should now write
373
374 FILE* f;
375 errno_t err = fopen_s(&f, __FILE__, "r");
376
377Currently, the warnings about these deprecations have been disabled by adding
378-D_CRT_SECURE_NO_DEPRECATE to the CFLAGS. It would be nice to remove that
379warning suppressant and actually make use of the new secure CRT functions.
380
381There is also a similar issue with POSIX CRT function names like fileno having
382been deprecated in favour of ISO C++ conformant names like _fileno. These
383warnings are also currently suppressed with the compiler option /wd4996. It
384might be nice to do as Microsoft suggest here too, although, unlike the secure
385functions issue, there is presumably little or no benefit in this case.
386
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387=head1 Tasks that need a knowledge of XS
388
389These tasks would need C knowledge, and roughly the level of knowledge of
390the perl API that comes from writing modules that use XS to interface to
391C.
392
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393=head2 autovivification
394
395Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict;
396
397This task is incremental - even a little bit of work on it will help.
398
399=head2 Unicode in Filenames
400
401chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open,
402opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen,
403system, truncate, unlink, utime, -X. All these could potentially accept
404Unicode filenames either as input or output (and in the case of system
405and qx Unicode in general, as input or output to/from the shell).
406Whether a filesystem - an operating system pair understands Unicode in
407filenames varies.
408
409Known combinations that have some level of understanding include
410Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac
411OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to
412create Unicode filenames, what forms of Unicode are accepted and used
413(UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used,
414and so on, varies. Finding the right level of interfacing to Perl
415requires some thought. Remember that an OS does not implicate a
416filesystem.
417
418(The Windows -C command flag "wide API support" has been at least
419temporarily retired in 5.8.1, and the -C has been repurposed, see
420L<perlrun>.)
421
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422Most probably the right way to do this would be this:
423L</"Virtualize operating system access">.
424
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425=head2 Unicode in %ENV
426
427Currently the %ENV entries are always byte strings.
87a942b1 428See L</"Virtualize operating system access">.
6d71adcd 429
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430=head2 Unicode and glob()
431
432Currently glob patterns and filenames returned from File::Glob::glob()
87a942b1 433are always byte strings. See L</"Virtualize operating system access">.
1f2e7916 434
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435=head2 use less 'memory'
436
437Investigate trade offs to switch out perl's choices on memory usage.
438Particularly perl should be able to give memory back.
439
440This task is incremental - even a little bit of work on it will help.
441
442=head2 Re-implement C<:unique> in a way that is actually thread-safe
443
444The old implementation made bad assumptions on several levels. A good 90%
445solution might be just to make C<:unique> work to share the string buffer
446of SvPVs. That way large constant strings can be shared between ithreads,
447such as the configuration information in F<Config>.
448
449=head2 Make tainting consistent
450
451Tainting would be easier to use if it didn't take documented shortcuts and
452allow taint to "leak" everywhere within an expression.
453
454=head2 readpipe(LIST)
455
456system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid
457running a shell. readpipe() (the function behind qx//) could be similarly
458extended.
459
460=head2 strcat(), strcpy(), strncat(), strncpy(), sprintf(), vsprintf()
461
462Maybe create a utility that checks after each libperl.a creation that
463none of the above (nor sprintf(), vsprintf(), or *SHUDDER* gets())
464ever creep back to libperl.a.
465
466 nm libperl.a | ./miniperl -alne '$o = $F[0] if /:$/; print "$o $F[1]" if $F[0] eq "U" && $F[1] =~ /^(?:strn?c(?:at|py)|v?sprintf|gets)$/'
467
468Note, of course, that this will only tell whether B<your> platform
469is using those naughty interfaces.
470
471=head2 Audit the code for destruction ordering assumptions
472
473Change 25773 notes
474
475 /* Need to check SvMAGICAL, as during global destruction it may be that
476 AvARYLEN(av) has been freed before av, and hence the SvANY() pointer
477 is now part of the linked list of SV heads, rather than pointing to
478 the original body. */
479 /* FIXME - audit the code for other bugs like this one. */
480
481adding the C<SvMAGICAL> check to
482
483 if (AvARYLEN(av) && SvMAGICAL(AvARYLEN(av))) {
484 MAGIC *mg = mg_find (AvARYLEN(av), PERL_MAGIC_arylen);
485
486Go through the core and look for similar assumptions that SVs have particular
487types, as all bets are off during global destruction.
488
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489=head2 Extend PerlIO and PerlIO::Scalar
490
491PerlIO::Scalar doesn't know how to truncate(). Implementing this
492would require extending the PerlIO vtable.
493
494Similarly the PerlIO vtable doesn't know about formats (write()), or
495about stat(), or chmod()/chown(), utime(), or flock().
496
497(For PerlIO::Scalar it's hard to see what e.g. mode bits or ownership
498would mean.)
499
500PerlIO doesn't do directories or symlinks, either: mkdir(), rmdir(),
501opendir(), closedir(), seekdir(), rewinddir(), glob(); symlink(),
502readlink().
503
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504See also L</"Virtualize operating system access">.
505
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506=head2 -C on the #! line
507
508It should be possible to make -C work correctly if found on the #! line,
509given that all perl command line options are strict ASCII, and -C changes
510only the interpretation of non-ASCII characters, and not for the script file
511handle. To make it work needs some investigation of the ordering of function
512calls during startup, and (by implication) a bit of tweaking of that order.
513
514
0bdfc961 515=head1 Tasks that need a knowledge of the interpreter
3298bd4d 516
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517These tasks would need C knowledge, and knowledge of how the interpreter works,
518or a willingness to learn.
3298bd4d 519
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520=head2 Implement $value ~~ 0 .. $range
521
522It would be nice to extend the syntax of the C<~~> operator to also
523understand numeric (and maybe alphanumeric) ranges.
524
d10fc472 525=head2 Attach/detach debugger from running program
1626a787 526
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527The old perltodo notes "With C<gdb>, you can attach the debugger to a running
528program if you pass the process ID. It would be good to do this with the Perl
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529debugger on a running Perl program, although I'm not sure how it would be
530done." ssh and screen do this with named pipes in /tmp. Maybe we can too.
1626a787 531
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532=head2 LVALUE functions for lists
533
534The old perltodo notes that lvalue functions don't work for list or hash
535slices. This would be good to fix.
536
537=head2 LVALUE functions in the debugger
538
539The old perltodo notes that lvalue functions don't work in the debugger. This
540would be good to fix.
541
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542=head2 regexp optimiser optional
543
544The regexp optimiser is not optional. It should configurable to be, to allow
545its performance to be measured, and its bugs to be easily demonstrated.
546
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547=head2 delete &function
548
549Allow to delete functions. One can already undef them, but they're still
550in the stash.
551
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552=head2 C</w> regex modifier
553
554That flag would enable to match whole words, and also to interpolate
555arrays as alternations. With it, C</P/w> would be roughly equivalent to:
556
557 do { local $"='|'; /\b(?:P)\b/ }
558
559See L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-01/msg00400.html>
560for the discussion.
561
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562=head2 optional optimizer
563
564Make the peephole optimizer optional. Currently it performs two tasks as
565it walks the optree - genuine peephole optimisations, and necessary fixups of
566ops. It would be good to find an efficient way to switch out the
567optimisations whilst keeping the fixups.
568
569=head2 You WANT *how* many
570
571Currently contexts are void, scalar and list. split has a special mechanism in
572place to pass in the number of return values wanted. It would be useful to
573have a general mechanism for this, backwards compatible and little speed hit.
574This would allow proposals such as short circuiting sort to be implemented
575as a module on CPAN.
576
577=head2 lexical aliases
578
579Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>.
580
581=head2 entersub XS vs Perl
582
583At the moment pp_entersub is huge, and has code to deal with entering both
584perl and XS subroutines. Subroutine implementations rarely change between
585perl and XS at run time, so investigate using 2 ops to enter subs (one for
586XS, one for perl) and swap between if a sub is redefined.
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587
588=head2 Self ties
589
590self ties are currently illegal because they caused too many segfaults. Maybe
591the causes of these could be tracked down and self-ties on all types re-
592instated.
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593
594=head2 Optimize away @_
595
596The old perltodo notes "Look at the "reification" code in C<av.c>".
597
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598=head2 Properly Unicode safe tokeniser and pads.
599
600The tokeniser isn't actually very UTF-8 clean. C<use utf8;> is a hack -
601variable names are stored in stashes as raw bytes, without the utf-8 flag
602set. The pad API only takes a C<char *> pointer, so that's all bytes too. The
603tokeniser ignores the UTF-8-ness of C<PL_rsfp>, or any SVs returned from
604source filters. All this could be fixed.
605
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606=head2 The yada yada yada operators
607
608Perl 6's Synopsis 3 says:
609
610I<The ... operator is the "yada, yada, yada" list operator, which is used as
611the body in function prototypes. It complains bitterly (by calling fail)
612if it is ever executed. Variant ??? calls warn, and !!! calls die.>
613
614Those would be nice to add to Perl 5. That could be done without new ops.
615
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616=head2 Virtualize operating system access
617
618Implement a set of "vtables" that virtualizes operating system access
619(open(), mkdir(), unlink(), readdir(), getenv(), etc.) At the very
620least these interfaces should take SVs as "name" arguments instead of
621bare char pointers; probably the most flexible and extensible way
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622would be for the Perl-facing interfaces to accept HVs. The system
623needs to be per-operating-system and per-file-system
624hookable/filterable, preferably both from XS and Perl level
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625(L<perlport/"Files and Filesystems"> is good reading at this point,
626in fact, all of L<perlport> is.)
627
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628This has actually already been implemented (but only for Win32),
629take a look at F<iperlsys.h> and F<win32/perlhost.h>. While all Win32
630variants go through a set of "vtables" for operating system access,
631non-Win32 systems currently go straight for the POSIX/UNIX-style
632system/library call. Similar system as for Win32 should be
633implemented for all platforms. The existing Win32 implementation
634probably does not need to survive alongside this proposed new
635implementation, the approaches could be merged.
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636
637What would this give us? One often-asked-for feature this would
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638enable is using Unicode for filenames, and other "names" like %ENV,
639usernames, hostnames, and so forth.
640(See L<perlunicode/"When Unicode Does Not Happen">.)
641
642But this kind of virtualization would also allow for things like
643virtual filesystems, virtual networks, and "sandboxes" (though as long
644as dynamic loading of random object code is allowed, not very safe
645sandboxes since external code of course know not of Perl's vtables).
646An example of a smaller "sandbox" is that this feature can be used to
647implement per-thread working directories: Win32 already does this.
648
649See also L</"Extend PerlIO and PerlIO::Scalar">.
87a942b1 650
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651=head1 Big projects
652
653Tasks that will get your name mentioned in the description of the "Highlights
87a942b1 654of 5.12"
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655
656=head2 make ithreads more robust
657
4e577f8b 658Generally make ithreads more robust. See also L</iCOW>
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659
660This task is incremental - even a little bit of work on it will help, and
661will be greatly appreciated.
662
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663One bit would be to write the missing code in sv.c:Perl_dirp_dup.
664
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665Fix Perl_sv_dup, et al so that threads can return objects.
666
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667=head2 iCOW
668
669Sarathy and Arthur have a proposal for an improved Copy On Write which
670specifically will be able to COW new ithreads. If this can be implemented
671it would be a good thing.
672
673=head2 (?{...}) closures in regexps
674
675Fix (or rewrite) the implementation of the C</(?{...})/> closures.
676
677=head2 A re-entrant regexp engine
678
679This will allow the use of a regex from inside (?{ }), (??{ }) and
680(?(?{ })|) constructs.
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682=head2 Add class set operations to regexp engine
683
684Apparently these are quite useful. Anyway, Jeffery Friedl wants them.
685
686demerphq has this on his todo list, but right at the bottom.