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 Make it clear from -v if this is the exact official release
337 Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that
338 usually defines one local patch, of the form "MAINT12345" or "RC1". The output
339 of perl -v doesn't report that a perl isn't an official release, and this
340 information can get lost in bugs reports. Because of this, the minor version
341 isn't bumped up until RC time, to minimise the possibility of versions of perl
342 escaping that believe themselves to be newer than they actually are.
344 It would be useful to find an elegant way to have the "this is an interim
345 maintenance release" or "this is a release candidate" in the terse -v output,
346 and have it so that it's easy for the pumpking to remove this just as the
347 release tarball is rolled up. This way the version pulled out of rsync would
348 always say "I'm a development release" and it would be safe to bump the
349 reported minor version as soon as a release ships, which would aid perl
352 This task is really about thinking of an elegant way to arrange the C source
353 such that it's trivial for the Pumpking to flag "this is an official release"
354 when making a tarball, yet leave the default source saying "I'm not the
357 =head2 Profile Perl - am I hot or not?
359 The Perl source code is stable enough that it makes sense to profile it,
360 identify and optimise the hotspots. It would be good to measure the
361 performance of the Perl interpreter using free tools such as cachegrind,
362 gprof, and dtrace, and work to reduce the bottlenecks they reveal.
364 As part of this, the idea of F<pp_hot.c> is that it contains the I<hot> ops,
365 the ops that are most commonly used. The idea is that by grouping them, their
366 object code will be adjacent in the executable, so they have a greater chance
367 of already being in the CPU cache (or swapped in) due to being near another op
370 Except that it's not clear if these really are the most commonly used ops. So
371 as part of exercising your skills with coverage and profiling tools you might
372 want to determine what ops I<really> are the most commonly used. And in turn
373 suggest evictions and promotions to achieve a better F<pp_hot.c>.
375 =head2 Allocate OPs from arenas
377 Currently all new OP structures are individually malloc()ed and free()d.
378 All C<malloc> implementations have space overheads, and are now as fast as
379 custom allocates so it would both use less memory and less CPU to allocate
380 the various OP structures from arenas. The SV arena code can probably be
383 Note that Configuring perl with C<-Accflags=-DPL_OP_SLAB_ALLOC> will use
384 Perl_Slab_alloc() to pack optrees into a contiguous block, which is
385 probably superior to the use of OP arenas, esp. from a cache locality
386 standpoint. See L<Profile Perl - am I hot or not?>.
388 =head2 Improve win32/wince.c
390 Currently, numerous functions look virtually, if not completely,
391 identical in both C<win32/wince.c> and C<win32/win32.c> files, which can't
394 =head2 Use secure CRT functions when building with VC8 on Win32
396 Visual C++ 2005 (VC++ 8.x) deprecated a number of CRT functions on the basis
397 that they were "unsafe" and introduced differently named secure versions of
398 them as replacements, e.g. instead of writing
400 FILE* f = fopen(__FILE__, "r");
405 errno_t err = fopen_s(&f, __FILE__, "r");
407 Currently, the warnings about these deprecations have been disabled by adding
408 -D_CRT_SECURE_NO_DEPRECATE to the CFLAGS. It would be nice to remove that
409 warning suppressant and actually make use of the new secure CRT functions.
411 There is also a similar issue with POSIX CRT function names like fileno having
412 been deprecated in favour of ISO C++ conformant names like _fileno. These
413 warnings are also currently suppressed by adding -D_CRT_NONSTDC_NO_DEPRECATE. It
414 might be nice to do as Microsoft suggest here too, although, unlike the secure
415 functions issue, there is presumably little or no benefit in this case.
417 =head1 Tasks that need a knowledge of XS
419 These tasks would need C knowledge, and roughly the level of knowledge of
420 the perl API that comes from writing modules that use XS to interface to
423 =head2 autovivification
425 Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict;
427 This task is incremental - even a little bit of work on it will help.
429 =head2 Unicode in Filenames
431 chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open,
432 opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen,
433 system, truncate, unlink, utime, -X. All these could potentially accept
434 Unicode filenames either as input or output (and in the case of system
435 and qx Unicode in general, as input or output to/from the shell).
436 Whether a filesystem - an operating system pair understands Unicode in
439 Known combinations that have some level of understanding include
440 Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac
441 OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to
442 create Unicode filenames, what forms of Unicode are accepted and used
443 (UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used,
444 and so on, varies. Finding the right level of interfacing to Perl
445 requires some thought. Remember that an OS does not implicate a
448 (The Windows -C command flag "wide API support" has been at least
449 temporarily retired in 5.8.1, and the -C has been repurposed, see
452 Most probably the right way to do this would be this:
453 L</"Virtualize operating system access">.
455 =head2 Unicode in %ENV
457 Currently the %ENV entries are always byte strings.
458 See L</"Virtualize operating system access">.
460 =head2 Unicode and glob()
462 Currently glob patterns and filenames returned from File::Glob::glob()
463 are always byte strings. See L</"Virtualize operating system access">.
465 =head2 Unicode and lc/uc operators
467 Some built-in operators (C<lc>, C<uc>, etc.) behave differently, based on
468 what the internal encoding of their argument is. That should not be the
469 case. Maybe add a pragma to switch behaviour.
471 =head2 use less 'memory'
473 Investigate trade offs to switch out perl's choices on memory usage.
474 Particularly perl should be able to give memory back.
476 This task is incremental - even a little bit of work on it will help.
478 =head2 Re-implement C<:unique> in a way that is actually thread-safe
480 The old implementation made bad assumptions on several levels. A good 90%
481 solution might be just to make C<:unique> work to share the string buffer
482 of SvPVs. That way large constant strings can be shared between ithreads,
483 such as the configuration information in F<Config>.
485 =head2 Make tainting consistent
487 Tainting would be easier to use if it didn't take documented shortcuts and
488 allow taint to "leak" everywhere within an expression.
490 =head2 readpipe(LIST)
492 system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid
493 running a shell. readpipe() (the function behind qx//) could be similarly
496 =head2 strcat(), strcpy(), strncat(), strncpy(), sprintf(), vsprintf()
498 Maybe create a utility that checks after each libperl.a creation that
499 none of the above (nor sprintf(), vsprintf(), or *SHUDDER* gets())
500 ever creep back to libperl.a.
502 nm libperl.a | ./miniperl -alne '$o = $F[0] if /:$/; print "$o $F[1]" if $F[0] eq "U" && $F[1] =~ /^(?:strn?c(?:at|py)|v?sprintf|gets)$/'
504 Note, of course, that this will only tell whether B<your> platform
505 is using those naughty interfaces.
507 =head2 Audit the code for destruction ordering assumptions
511 /* Need to check SvMAGICAL, as during global destruction it may be that
512 AvARYLEN(av) has been freed before av, and hence the SvANY() pointer
513 is now part of the linked list of SV heads, rather than pointing to
514 the original body. */
515 /* FIXME - audit the code for other bugs like this one. */
517 adding the C<SvMAGICAL> check to
519 if (AvARYLEN(av) && SvMAGICAL(AvARYLEN(av))) {
520 MAGIC *mg = mg_find (AvARYLEN(av), PERL_MAGIC_arylen);
522 Go through the core and look for similar assumptions that SVs have particular
523 types, as all bets are off during global destruction.
525 =head2 Extend PerlIO and PerlIO::Scalar
527 PerlIO::Scalar doesn't know how to truncate(). Implementing this
528 would require extending the PerlIO vtable.
530 Similarly the PerlIO vtable doesn't know about formats (write()), or
531 about stat(), or chmod()/chown(), utime(), or flock().
533 (For PerlIO::Scalar it's hard to see what e.g. mode bits or ownership
536 PerlIO doesn't do directories or symlinks, either: mkdir(), rmdir(),
537 opendir(), closedir(), seekdir(), rewinddir(), glob(); symlink(),
540 See also L</"Virtualize operating system access">.
542 =head2 -C on the #! line
544 It should be possible to make -C work correctly if found on the #! line,
545 given that all perl command line options are strict ASCII, and -C changes
546 only the interpretation of non-ASCII characters, and not for the script file
547 handle. To make it work needs some investigation of the ordering of function
548 calls during startup, and (by implication) a bit of tweaking of that order.
551 =head1 Tasks that need a knowledge of the interpreter
553 These tasks would need C knowledge, and knowledge of how the interpreter works,
554 or a willingness to learn.
556 =head2 state variable initialization in list context
558 Currently this is illegal:
560 state ($a, $b) = foo();
562 The current Perl 6 design is that C<state ($a) = foo();> and
563 C<(state $a) = foo();> have different semantics, which is tricky to implement
564 in Perl 5 as currently the produce the same opcode trees. It would be useful
565 to clarify that the Perl 6 design is firm, and then implement the necessary
566 code in Perl 5. There are comments in C<Perl_newASSIGNOP()> that show the
567 code paths taken by various assignment constructions involving state variables.
569 =head2 Implement $value ~~ 0 .. $range
571 It would be nice to extend the syntax of the C<~~> operator to also
572 understand numeric (and maybe alphanumeric) ranges.
574 =head2 A does() built-in
576 Like ref(), only useful. It would call the C<DOES> method on objects; it
577 would also tell whether something can be dereferenced as an
578 array/hash/etc., or used as a regexp, etc.
579 L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-03/msg00481.html>
581 =head2 Tied filehandles and write() don't mix
583 There is no method on tied filehandles to allow them to be called back by
586 =head2 Attach/detach debugger from running program
588 The old perltodo notes "With C<gdb>, you can attach the debugger to a running
589 program if you pass the process ID. It would be good to do this with the Perl
590 debugger on a running Perl program, although I'm not sure how it would be
591 done." ssh and screen do this with named pipes in /tmp. Maybe we can too.
593 =head2 Optimize away empty destructors
595 Defining an empty DESTROY method might be useful (notably in
596 AUTOLOAD-enabled classes), but it's still a bit expensive to call. That
597 could probably be optimized.
599 =head2 LVALUE functions for lists
601 The old perltodo notes that lvalue functions don't work for list or hash
602 slices. This would be good to fix.
604 =head2 LVALUE functions in the debugger
606 The old perltodo notes that lvalue functions don't work in the debugger. This
607 would be good to fix.
609 =head2 regexp optimiser optional
611 The regexp optimiser is not optional. It should configurable to be, to allow
612 its performance to be measured, and its bugs to be easily demonstrated.
614 =head2 delete &function
616 Allow to delete functions. One can already undef them, but they're still
619 =head2 C</w> regex modifier
621 That flag would enable to match whole words, and also to interpolate
622 arrays as alternations. With it, C</P/w> would be roughly equivalent to:
624 do { local $"='|'; /\b(?:P)\b/ }
626 See L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-01/msg00400.html>
629 =head2 optional optimizer
631 Make the peephole optimizer optional. Currently it performs two tasks as
632 it walks the optree - genuine peephole optimisations, and necessary fixups of
633 ops. It would be good to find an efficient way to switch out the
634 optimisations whilst keeping the fixups.
636 =head2 You WANT *how* many
638 Currently contexts are void, scalar and list. split has a special mechanism in
639 place to pass in the number of return values wanted. It would be useful to
640 have a general mechanism for this, backwards compatible and little speed hit.
641 This would allow proposals such as short circuiting sort to be implemented
644 =head2 lexical aliases
646 Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>.
648 =head2 entersub XS vs Perl
650 At the moment pp_entersub is huge, and has code to deal with entering both
651 perl and XS subroutines. Subroutine implementations rarely change between
652 perl and XS at run time, so investigate using 2 ops to enter subs (one for
653 XS, one for perl) and swap between if a sub is redefined.
657 self ties are currently illegal because they caused too many segfaults. Maybe
658 the causes of these could be tracked down and self-ties on all types re-
661 =head2 Optimize away @_
663 The old perltodo notes "Look at the "reification" code in C<av.c>".
665 =head2 Properly Unicode safe tokeniser and pads.
667 The tokeniser isn't actually very UTF-8 clean. C<use utf8;> is a hack -
668 variable names are stored in stashes as raw bytes, without the utf-8 flag
669 set. The pad API only takes a C<char *> pointer, so that's all bytes too. The
670 tokeniser ignores the UTF-8-ness of C<PL_rsfp>, or any SVs returned from
671 source filters. All this could be fixed.
673 =head2 The yada yada yada operators
675 Perl 6's Synopsis 3 says:
677 I<The ... operator is the "yada, yada, yada" list operator, which is used as
678 the body in function prototypes. It complains bitterly (by calling fail)
679 if it is ever executed. Variant ??? calls warn, and !!! calls die.>
681 Those would be nice to add to Perl 5. That could be done without new ops.
683 =head2 Virtualize operating system access
685 Implement a set of "vtables" that virtualizes operating system access
686 (open(), mkdir(), unlink(), readdir(), getenv(), etc.) At the very
687 least these interfaces should take SVs as "name" arguments instead of
688 bare char pointers; probably the most flexible and extensible way
689 would be for the Perl-facing interfaces to accept HVs. The system
690 needs to be per-operating-system and per-file-system
691 hookable/filterable, preferably both from XS and Perl level
692 (L<perlport/"Files and Filesystems"> is good reading at this point,
693 in fact, all of L<perlport> is.)
695 This has actually already been implemented (but only for Win32),
696 take a look at F<iperlsys.h> and F<win32/perlhost.h>. While all Win32
697 variants go through a set of "vtables" for operating system access,
698 non-Win32 systems currently go straight for the POSIX/UNIX-style
699 system/library call. Similar system as for Win32 should be
700 implemented for all platforms. The existing Win32 implementation
701 probably does not need to survive alongside this proposed new
702 implementation, the approaches could be merged.
704 What would this give us? One often-asked-for feature this would
705 enable is using Unicode for filenames, and other "names" like %ENV,
706 usernames, hostnames, and so forth.
707 (See L<perlunicode/"When Unicode Does Not Happen">.)
709 But this kind of virtualization would also allow for things like
710 virtual filesystems, virtual networks, and "sandboxes" (though as long
711 as dynamic loading of random object code is allowed, not very safe
712 sandboxes since external code of course know not of Perl's vtables).
713 An example of a smaller "sandbox" is that this feature can be used to
714 implement per-thread working directories: Win32 already does this.
716 See also L</"Extend PerlIO and PerlIO::Scalar">.
720 Tasks that will get your name mentioned in the description of the "Highlights
723 =head2 make ithreads more robust
725 Generally make ithreads more robust. See also L</iCOW>
727 This task is incremental - even a little bit of work on it will help, and
728 will be greatly appreciated.
730 One bit would be to write the missing code in sv.c:Perl_dirp_dup.
732 Fix Perl_sv_dup, et al so that threads can return objects.
736 Sarathy and Arthur have a proposal for an improved Copy On Write which
737 specifically will be able to COW new ithreads. If this can be implemented
738 it would be a good thing.
740 =head2 (?{...}) closures in regexps
742 Fix (or rewrite) the implementation of the C</(?{...})/> closures.
744 =head2 A re-entrant regexp engine
746 This will allow the use of a regex from inside (?{ }), (??{ }) and
747 (?(?{ })|) constructs.
749 =head2 Add class set operations to regexp engine
751 Apparently these are quite useful. Anyway, Jeffery Friedl wants them.
753 demerphq has this on his todo list, but right at the bottom.