3 perltodo - Perl TO-DO List
7 This is a list of wishes for Perl. The tasks we think are smaller or easier
8 are listed first. Anyone is welcome to work on any of these, but it's a good
9 idea to first contact I<perl5-porters@perl.org> to avoid duplication of
10 effort. By all means contact a pumpking privately first if you prefer.
12 Whilst patches to make the list shorter are most welcome, ideas to add to
13 the list are also encouraged. Check the perl5-porters archives for past
14 ideas, and any discussion about them. One set of archives may be found at:
16 http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/
18 What can we offer you in return? Fame, fortune, and everlasting glory? Maybe
19 not, but if your patch is incorporated, then we'll add your name to the
20 F<AUTHORS> file, which ships in the official distribution. How many other
21 programming languages offer you 1 line of immortality?
23 =head1 Tasks that only need Perl knowledge
25 =head2 common test code for timed bail out
27 Write portable self destruct code for tests to stop them burning CPU in
28 infinite loops. This needs to avoid using alarm, as some of the tests are
29 testing alarm/sleep or timers.
31 =head2 POD -E<gt> HTML conversion in the core still sucks
33 Which is crazy given just how simple POD purports to be, and how simple HTML
34 can be. It's not actually I<as> simple as it sounds, particularly with the
35 flexibility POD allows for C<=item>, but it would be good to improve the
36 visual appeal of the HTML generated, and to avoid it having any validation
37 errors. See also L</make HTML install work>, as the layout of installation tree
38 is needed to improve the cross-linking.
40 The addition of C<Pod::Simple> and its related modules may make this task
43 =head2 Parallel testing
45 (This probably impacts much more than the core: also the Test::Harness
46 and TAP::* modules on CPAN.)
48 The core regression test suite is getting ever more comprehensive, which has
49 the side effect that it takes longer to run. This isn't so good. Investigate
50 whether it would be feasible to give the harness script the B<option> of
51 running sets of tests in parallel. This would be useful for tests in
52 F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>.
60 How does screen layout work when you're running more than one test?
64 How does the caller of test specify how many tests to run in parallel?
68 How do setup/teardown tests identify themselves?
72 Pugs already does parallel testing - can their approach be re-used?
74 =head2 Make Schwern poorer
76 We should have tests for everything. When all the core's modules are tested,
77 Schwern has promised to donate to $500 to TPF. We may need volunteers to
78 hold him upside down and shake vigorously in order to actually extract the
81 =head2 Improve the coverage of the core tests
83 Use Devel::Cover to ascertain the core modules's test coverage, then add
84 tests that are currently missing.
88 A full test suite for the B module would be nice.
90 =head2 Deparse inlined constants
97 will currently deparse as
99 use constant ('PI', 4);
102 because the tokenizer inlines the value of the constant subroutine C<PI>.
103 This allows various compile time optimisations, such as constant folding
104 and dead code elimination. Where these haven't happened (such as the example
105 above) it ought be possible to make B::Deparse work out the name of the
106 original constant, because just enough information survives in the symbol
107 table to do this. Specifically, the same scalar is used for the constant in
108 the optree as is used for the constant subroutine, so by iterating over all
109 symbol tables and generating a mapping of SV address to constant name, it
110 would be possible to provide B::Deparse with this functionality.
112 =head2 A decent benchmark
114 C<perlbench> seems impervious to any recent changes made to the perl core. It
115 would be useful to have a reasonable general benchmarking suite that roughly
116 represented what current perl programs do, and measurably reported whether
117 tweaks to the core improve, degrade or don't really affect performance, to
118 guide people attempting to optimise the guts of perl. Gisle would welcome
119 new tests for perlbench.
121 =head2 fix tainting bugs
123 Fix the bugs revealed by running the test suite with the C<-t> switch (via
124 C<make test.taintwarn>).
126 =head2 Dual life everything
128 As part of the "dists" plan, anything that doesn't belong in the smallest perl
129 distribution needs to be dual lifed. Anything else can be too. Figure out what
130 changes would be needed to package that module and its tests up for CPAN, and
131 do so. Test it with older perl releases, and fix the problems you find.
133 To make a minimal perl distribution, it's useful to look at
134 F<t/lib/commonsense.t>.
136 =head2 Improving C<threads::shared>
138 Investigate whether C<threads::shared> could share aggregates properly with
139 only Perl level changes to shared.pm
141 =head2 POSIX memory footprint
143 Ilya observed that use POSIX; eats memory like there's no tomorrow, and at
144 various times worked to cut it down. There is probably still fat to cut out -
145 for example POSIX passes Exporter some very memory hungry data structures.
147 =head2 embed.pl/makedef.pl
149 There is a script F<embed.pl> that generates several header files to prefix
150 all of Perl's symbols in a consistent way, to provide some semblance of
151 namespace support in C<C>. Functions are declared in F<embed.fnc>, variables
152 in F<interpvar.h>. Quite a few of the functions and variables
153 are conditionally declared there, using C<#ifdef>. However, F<embed.pl>
154 doesn't understand the C macros, so the rules about which symbols are present
155 when is duplicated in F<makedef.pl>. Writing things twice is bad, m'kay.
156 It would be good to teach C<embed.pl> to understand the conditional
157 compilation, and hence remove the duplication, and the mistakes it has caused.
159 =head2 use strict; and AutoLoad
161 Currently if you write
164 use AutoLoader 'AUTOLOAD';
169 print join (' ', No, strict, here), "!\n";
172 then C<use strict;> isn't in force within the autoloaded subroutines. It would
173 be more consistent (and less surprising) to arrange for all lexical pragmas
174 in force at the __END__ block to be in force within each autoloaded subroutine.
176 There's a similar problem with SelfLoader.
178 =head1 Tasks that need a little sysadmin-type knowledge
180 Or if you prefer, tasks that you would learn from, and broaden your skills
183 =head2 make HTML install work
185 There is an C<installhtml> target in the Makefile. It's marked as
186 "experimental". It would be good to get this tested, make it work reliably, and
187 remove the "experimental" tag. This would include
193 Checking that cross linking between various parts of the documentation works.
194 In particular that links work between the modules (files with POD in F<lib/>)
195 and the core documentation (files in F<pod/>)
199 Work out how to split C<perlfunc> into chunks, preferably one per function
200 group, preferably with general case code that could be used elsewhere.
201 Challenges here are correctly identifying the groups of functions that go
202 together, and making the right named external cross-links point to the right
203 page. Things to be aware of are C<-X>, groups such as C<getpwnam> to
204 C<endservent>, two or more C<=items> giving the different parameter lists, such
207 =item substr EXPR,OFFSET,LENGTH,REPLACEMENT
208 =item substr EXPR,OFFSET,LENGTH
209 =item substr EXPR,OFFSET
211 and different parameter lists having different meanings. (eg C<select>)
215 =head2 compressed man pages
217 Be able to install them. This would probably need a configure test to see how
218 the system does compressed man pages (same directory/different directory?
219 same filename/different filename), as well as tweaking the F<installman> script
220 to compress as necessary.
222 =head2 Add a code coverage target to the Makefile
224 Make it easy for anyone to run Devel::Cover on the core's tests. The steps
225 to do this manually are roughly
231 do a normal C<Configure>, but include Devel::Cover as a module to install
232 (see F<INSTALL> for how to do this)
240 cd t; HARNESS_PERL_SWITCHES=-MDevel::Cover ./perl -I../lib harness
244 Process the resulting Devel::Cover database
248 This just give you the coverage of the F<.pm>s. To also get the C level
255 Additionally tell C<Configure> to use the appropriate C compiler flags for
262 (instead of C<make perl>)
266 After running the tests run C<gcov> to generate all the F<.gcov> files.
267 (Including down in the subdirectories of F<ext/>
271 (From the top level perl directory) run C<gcov2perl> on all the C<.gcov> files
272 to get their stats into the cover_db directory.
276 Then process the Devel::Cover database
280 It would be good to add a single switch to C<Configure> to specify that you
281 wanted to perform perl level coverage, and another to specify C level
282 coverage, and have C<Configure> and the F<Makefile> do all the right things
285 =head2 Make Config.pm cope with differences between built and installed perl
287 Quite often vendors ship a perl binary compiled with their (pay-for)
288 compilers. People install a free compiler, such as gcc. To work out how to
289 build extensions, Perl interrogates C<%Config>, so in this situation
290 C<%Config> describes compilers that aren't there, and extension building
291 fails. This forces people into choosing between re-compiling perl themselves
292 using the compiler they have, or only using modules that the vendor ships.
294 It would be good to find a way teach C<Config.pm> about the installation setup,
295 possibly involving probing at install time or later, so that the C<%Config> in
296 a binary distribution better describes the installed machine, when the
297 installed machine differs from the build machine in some significant way.
299 =head2 linker specification files
301 Some platforms mandate that you provide a list of a shared library's external
302 symbols to the linker, so the core already has the infrastructure in place to
303 do this for generating shared perl libraries. My understanding is that the
304 GNU toolchain can accept an optional linker specification file, and restrict
305 visibility just to symbols declared in that file. It would be good to extend
306 F<makedef.pl> to support this format, and to provide a means within
307 C<Configure> to enable it. This would allow Unix users to test that the
308 export list is correct, and to build a perl that does not pollute the global
309 namespace with private symbols.
311 =head2 Cross-compile support
313 Currently C<Configure> understands C<-Dusecrosscompile> option. This option
314 arranges for building C<miniperl> for TARGET machine, so this C<miniperl> is
315 assumed then to be copied to TARGET machine and used as a replacement of full
318 This could be done little differently. Namely C<miniperl> should be built for
319 HOST and then full C<perl> with extensions should be compiled for TARGET.
320 This, however, might require extra trickery for %Config: we have one config
321 first for HOST and then another for TARGET. Tools like MakeMaker will be
322 mightily confused. Having around two different types of executables and
323 libraries (HOST and TARGET) makes life interesting for Makefiles and
324 shell (and Perl) scripts. There is $Config{run}, normally empty, which
325 can be used as an execution wrapper. Also note that in some
326 cross-compilation/execution environments the HOST and the TARGET do
327 not see the same filesystem(s), the $Config{run} may need to do some
328 file/directory copying back and forth.
330 =head1 Tasks that need a little C knowledge
332 These tasks would need a little C knowledge, but don't need any specific
333 background or experience with XS, or how the Perl interpreter works
335 =head2 Modernize the order of directories in @INC
337 The way @INC is laid out by default, one cannot upgrade core (dual-life)
338 modules without overwriting files. This causes problems for binary
343 Natively 64-bit systems need neither -Duse64bitint nor -Duse64bitall.
344 On these systems, it might be the default compilation mode, and there
345 is currently no guarantee that passing no use64bitall option to the
346 Configure process will build a 32bit perl. Implementing -Duse32bit*
347 options would be nice for perl 5.12.
349 =head2 Make it clear from -v if this is the exact official release
351 Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that
352 usually defines one local patch, of the form "MAINT12345" or "RC1". The output
353 of perl -v doesn't report that a perl isn't an official release, and this
354 information can get lost in bugs reports. Because of this, the minor version
355 isn't bumped up until RC time, to minimise the possibility of versions of perl
356 escaping that believe themselves to be newer than they actually are.
358 It would be useful to find an elegant way to have the "this is an interim
359 maintenance release" or "this is a release candidate" in the terse -v output,
360 and have it so that it's easy for the pumpking to remove this just as the
361 release tarball is rolled up. This way the version pulled out of rsync would
362 always say "I'm a development release" and it would be safe to bump the
363 reported minor version as soon as a release ships, which would aid perl
366 This task is really about thinking of an elegant way to arrange the C source
367 such that it's trivial for the Pumpking to flag "this is an official release"
368 when making a tarball, yet leave the default source saying "I'm not the
371 =head2 Profile Perl - am I hot or not?
373 The Perl source code is stable enough that it makes sense to profile it,
374 identify and optimise the hotspots. It would be good to measure the
375 performance of the Perl interpreter using free tools such as cachegrind,
376 gprof, and dtrace, and work to reduce the bottlenecks they reveal.
378 As part of this, the idea of F<pp_hot.c> is that it contains the I<hot> ops,
379 the ops that are most commonly used. The idea is that by grouping them, their
380 object code will be adjacent in the executable, so they have a greater chance
381 of already being in the CPU cache (or swapped in) due to being near another op
384 Except that it's not clear if these really are the most commonly used ops. So
385 as part of exercising your skills with coverage and profiling tools you might
386 want to determine what ops I<really> are the most commonly used. And in turn
387 suggest evictions and promotions to achieve a better F<pp_hot.c>.
389 =head2 Allocate OPs from arenas
391 Currently all new OP structures are individually malloc()ed and free()d.
392 All C<malloc> implementations have space overheads, and are now as fast as
393 custom allocates so it would both use less memory and less CPU to allocate
394 the various OP structures from arenas. The SV arena code can probably be
397 Note that Configuring perl with C<-Accflags=-DPL_OP_SLAB_ALLOC> will use
398 Perl_Slab_alloc() to pack optrees into a contiguous block, which is
399 probably superior to the use of OP arenas, esp. from a cache locality
400 standpoint. See L<Profile Perl - am I hot or not?>.
402 =head2 Improve win32/wince.c
404 Currently, numerous functions look virtually, if not completely,
405 identical in both C<win32/wince.c> and C<win32/win32.c> files, which can't
408 =head2 Use secure CRT functions when building with VC8 on Win32
410 Visual C++ 2005 (VC++ 8.x) deprecated a number of CRT functions on the basis
411 that they were "unsafe" and introduced differently named secure versions of
412 them as replacements, e.g. instead of writing
414 FILE* f = fopen(__FILE__, "r");
419 errno_t err = fopen_s(&f, __FILE__, "r");
421 Currently, the warnings about these deprecations have been disabled by adding
422 -D_CRT_SECURE_NO_DEPRECATE to the CFLAGS. It would be nice to remove that
423 warning suppressant and actually make use of the new secure CRT functions.
425 There is also a similar issue with POSIX CRT function names like fileno having
426 been deprecated in favour of ISO C++ conformant names like _fileno. These
427 warnings are also currently suppressed by adding -D_CRT_NONSTDC_NO_DEPRECATE. It
428 might be nice to do as Microsoft suggest here too, although, unlike the secure
429 functions issue, there is presumably little or no benefit in this case.
431 =head2 __FUNCTION__ for MSVC-pre-7.0
433 Jarkko notes that one can things morally equivalent to C<__FUNCTION__>
434 (or C<__func__>) even in MSVC-pre-7.0, contrary to popular belief.
435 See L<http://www.codeproject.com/debug/extendedtrace.asp> if you feel like
436 making C<PERL_MEM_LOG> more useful on Win32.
438 =head1 Tasks that need a knowledge of XS
440 These tasks would need C knowledge, and roughly the level of knowledge of
441 the perl API that comes from writing modules that use XS to interface to
444 =head2 autovivification
446 Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict;
448 This task is incremental - even a little bit of work on it will help.
450 =head2 Unicode in Filenames
452 chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open,
453 opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen,
454 system, truncate, unlink, utime, -X. All these could potentially accept
455 Unicode filenames either as input or output (and in the case of system
456 and qx Unicode in general, as input or output to/from the shell).
457 Whether a filesystem - an operating system pair understands Unicode in
460 Known combinations that have some level of understanding include
461 Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac
462 OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to
463 create Unicode filenames, what forms of Unicode are accepted and used
464 (UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used,
465 and so on, varies. Finding the right level of interfacing to Perl
466 requires some thought. Remember that an OS does not implicate a
469 (The Windows -C command flag "wide API support" has been at least
470 temporarily retired in 5.8.1, and the -C has been repurposed, see
473 Most probably the right way to do this would be this:
474 L</"Virtualize operating system access">.
476 =head2 Unicode in %ENV
478 Currently the %ENV entries are always byte strings.
479 See L</"Virtualize operating system access">.
481 =head2 Unicode and glob()
483 Currently glob patterns and filenames returned from File::Glob::glob()
484 are always byte strings. See L</"Virtualize operating system access">.
486 =head2 Unicode and lc/uc operators
488 Some built-in operators (C<lc>, C<uc>, etc.) behave differently, based on
489 what the internal encoding of their argument is. That should not be the
490 case. Maybe add a pragma to switch behaviour.
492 =head2 use less 'memory'
494 Investigate trade offs to switch out perl's choices on memory usage.
495 Particularly perl should be able to give memory back.
497 This task is incremental - even a little bit of work on it will help.
499 =head2 Re-implement C<:unique> in a way that is actually thread-safe
501 The old implementation made bad assumptions on several levels. A good 90%
502 solution might be just to make C<:unique> work to share the string buffer
503 of SvPVs. That way large constant strings can be shared between ithreads,
504 such as the configuration information in F<Config>.
506 =head2 Make tainting consistent
508 Tainting would be easier to use if it didn't take documented shortcuts and
509 allow taint to "leak" everywhere within an expression.
511 =head2 readpipe(LIST)
513 system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid
514 running a shell. readpipe() (the function behind qx//) could be similarly
517 =head2 strcat(), strcpy(), strncat(), strncpy(), sprintf(), vsprintf()
519 Maybe create a utility that checks after each libperl.a creation that
520 none of the above (nor sprintf(), vsprintf(), or *SHUDDER* gets())
521 ever creep back to libperl.a.
523 nm libperl.a | ./miniperl -alne '$o = $F[0] if /:$/; print "$o $F[1]" if $F[0] eq "U" && $F[1] =~ /^(?:strn?c(?:at|py)|v?sprintf|gets)$/'
525 Note, of course, that this will only tell whether B<your> platform
526 is using those naughty interfaces.
528 =head2 Audit the code for destruction ordering assumptions
532 /* Need to check SvMAGICAL, as during global destruction it may be that
533 AvARYLEN(av) has been freed before av, and hence the SvANY() pointer
534 is now part of the linked list of SV heads, rather than pointing to
535 the original body. */
536 /* FIXME - audit the code for other bugs like this one. */
538 adding the C<SvMAGICAL> check to
540 if (AvARYLEN(av) && SvMAGICAL(AvARYLEN(av))) {
541 MAGIC *mg = mg_find (AvARYLEN(av), PERL_MAGIC_arylen);
543 Go through the core and look for similar assumptions that SVs have particular
544 types, as all bets are off during global destruction.
546 =head2 Extend PerlIO and PerlIO::Scalar
548 PerlIO::Scalar doesn't know how to truncate(). Implementing this
549 would require extending the PerlIO vtable.
551 Similarly the PerlIO vtable doesn't know about formats (write()), or
552 about stat(), or chmod()/chown(), utime(), or flock().
554 (For PerlIO::Scalar it's hard to see what e.g. mode bits or ownership
557 PerlIO doesn't do directories or symlinks, either: mkdir(), rmdir(),
558 opendir(), closedir(), seekdir(), rewinddir(), glob(); symlink(),
561 See also L</"Virtualize operating system access">.
563 =head2 -C on the #! line
565 It should be possible to make -C work correctly if found on the #! line,
566 given that all perl command line options are strict ASCII, and -C changes
567 only the interpretation of non-ASCII characters, and not for the script file
568 handle. To make it work needs some investigation of the ordering of function
569 calls during startup, and (by implication) a bit of tweaking of that order.
572 =head1 Tasks that need a knowledge of the interpreter
574 These tasks would need C knowledge, and knowledge of how the interpreter works,
575 or a willingness to learn.
577 =head2 state variable initialization in list context
579 Currently this is illegal:
581 state ($a, $b) = foo();
583 The current Perl 6 design is that C<state ($a) = foo();> and
584 C<(state $a) = foo();> have different semantics, which is tricky to implement
585 in Perl 5 as currently the produce the same opcode trees. It would be useful
586 to clarify that the Perl 6 design is firm, and then implement the necessary
587 code in Perl 5. There are comments in C<Perl_newASSIGNOP()> that show the
588 code paths taken by various assignment constructions involving state variables.
590 =head2 Implement $value ~~ 0 .. $range
592 It would be nice to extend the syntax of the C<~~> operator to also
593 understand numeric (and maybe alphanumeric) ranges.
595 =head2 A does() built-in
597 Like ref(), only useful. It would call the C<DOES> method on objects; it
598 would also tell whether something can be dereferenced as an
599 array/hash/etc., or used as a regexp, etc.
600 L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-03/msg00481.html>
602 =head2 Tied filehandles and write() don't mix
604 There is no method on tied filehandles to allow them to be called back by
607 =head2 Attach/detach debugger from running program
609 The old perltodo notes "With C<gdb>, you can attach the debugger to a running
610 program if you pass the process ID. It would be good to do this with the Perl
611 debugger on a running Perl program, although I'm not sure how it would be
612 done." ssh and screen do this with named pipes in /tmp. Maybe we can too.
614 =head2 Optimize away empty destructors
616 Defining an empty DESTROY method might be useful (notably in
617 AUTOLOAD-enabled classes), but it's still a bit expensive to call. That
618 could probably be optimized.
620 =head2 LVALUE functions for lists
622 The old perltodo notes that lvalue functions don't work for list or hash
623 slices. This would be good to fix.
625 =head2 LVALUE functions in the debugger
627 The old perltodo notes that lvalue functions don't work in the debugger. This
628 would be good to fix.
630 =head2 regexp optimiser optional
632 The regexp optimiser is not optional. It should configurable to be, to allow
633 its performance to be measured, and its bugs to be easily demonstrated.
635 =head2 delete &function
637 Allow to delete functions. One can already undef them, but they're still
640 =head2 C</w> regex modifier
642 That flag would enable to match whole words, and also to interpolate
643 arrays as alternations. With it, C</P/w> would be roughly equivalent to:
645 do { local $"='|'; /\b(?:P)\b/ }
647 See L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-01/msg00400.html>
650 =head2 optional optimizer
652 Make the peephole optimizer optional. Currently it performs two tasks as
653 it walks the optree - genuine peephole optimisations, and necessary fixups of
654 ops. It would be good to find an efficient way to switch out the
655 optimisations whilst keeping the fixups.
657 =head2 You WANT *how* many
659 Currently contexts are void, scalar and list. split has a special mechanism in
660 place to pass in the number of return values wanted. It would be useful to
661 have a general mechanism for this, backwards compatible and little speed hit.
662 This would allow proposals such as short circuiting sort to be implemented
665 =head2 lexical aliases
667 Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>.
669 =head2 entersub XS vs Perl
671 At the moment pp_entersub is huge, and has code to deal with entering both
672 perl and XS subroutines. Subroutine implementations rarely change between
673 perl and XS at run time, so investigate using 2 ops to enter subs (one for
674 XS, one for perl) and swap between if a sub is redefined.
678 self ties are currently illegal because they caused too many segfaults. Maybe
679 the causes of these could be tracked down and self-ties on all types re-
682 =head2 Optimize away @_
684 The old perltodo notes "Look at the "reification" code in C<av.c>".
686 =head2 Properly Unicode safe tokeniser and pads.
688 The tokeniser isn't actually very UTF-8 clean. C<use utf8;> is a hack -
689 variable names are stored in stashes as raw bytes, without the utf-8 flag
690 set. The pad API only takes a C<char *> pointer, so that's all bytes too. The
691 tokeniser ignores the UTF-8-ness of C<PL_rsfp>, or any SVs returned from
692 source filters. All this could be fixed.
694 =head2 The yada yada yada operators
696 Perl 6's Synopsis 3 says:
698 I<The ... operator is the "yada, yada, yada" list operator, which is used as
699 the body in function prototypes. It complains bitterly (by calling fail)
700 if it is ever executed. Variant ??? calls warn, and !!! calls die.>
702 Those would be nice to add to Perl 5. That could be done without new ops.
704 =head2 Virtualize operating system access
706 Implement a set of "vtables" that virtualizes operating system access
707 (open(), mkdir(), unlink(), readdir(), getenv(), etc.) At the very
708 least these interfaces should take SVs as "name" arguments instead of
709 bare char pointers; probably the most flexible and extensible way
710 would be for the Perl-facing interfaces to accept HVs. The system
711 needs to be per-operating-system and per-file-system
712 hookable/filterable, preferably both from XS and Perl level
713 (L<perlport/"Files and Filesystems"> is good reading at this point,
714 in fact, all of L<perlport> is.)
716 This has actually already been implemented (but only for Win32),
717 take a look at F<iperlsys.h> and F<win32/perlhost.h>. While all Win32
718 variants go through a set of "vtables" for operating system access,
719 non-Win32 systems currently go straight for the POSIX/UNIX-style
720 system/library call. Similar system as for Win32 should be
721 implemented for all platforms. The existing Win32 implementation
722 probably does not need to survive alongside this proposed new
723 implementation, the approaches could be merged.
725 What would this give us? One often-asked-for feature this would
726 enable is using Unicode for filenames, and other "names" like %ENV,
727 usernames, hostnames, and so forth.
728 (See L<perlunicode/"When Unicode Does Not Happen">.)
730 But this kind of virtualization would also allow for things like
731 virtual filesystems, virtual networks, and "sandboxes" (though as long
732 as dynamic loading of random object code is allowed, not very safe
733 sandboxes since external code of course know not of Perl's vtables).
734 An example of a smaller "sandbox" is that this feature can be used to
735 implement per-thread working directories: Win32 already does this.
737 See also L</"Extend PerlIO and PerlIO::Scalar">.
741 Tasks that will get your name mentioned in the description of the "Highlights
744 =head2 make ithreads more robust
746 Generally make ithreads more robust. See also L</iCOW>
748 This task is incremental - even a little bit of work on it will help, and
749 will be greatly appreciated.
751 One bit would be to write the missing code in sv.c:Perl_dirp_dup.
753 Fix Perl_sv_dup, et al so that threads can return objects.
757 Sarathy and Arthur have a proposal for an improved Copy On Write which
758 specifically will be able to COW new ithreads. If this can be implemented
759 it would be a good thing.
761 =head2 (?{...}) closures in regexps
763 Fix (or rewrite) the implementation of the C</(?{...})/> closures.
765 =head2 A re-entrant regexp engine
767 This will allow the use of a regex from inside (?{ }), (??{ }) and
768 (?(?{ })|) constructs.
770 =head2 Add class set operations to regexp engine
772 Apparently these are quite useful. Anyway, Jeffery Friedl wants them.
774 demerphq has this on his todo list, but right at the bottom.