3 perltodo - Perl TO-DO List
7 This is a list of wishes for Perl. Send updates to
8 I<perl5-porters@perl.org>. If you want to work on any of these
9 projects, be sure to check the perl5-porters archives for past ideas,
10 flames, and propaganda. This will save you time and also prevent you
11 from implementing something that Larry has already vetoed. One set
12 of archives may be found at:
14 http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/
16 =head1 To do during 5.6.x
18 =head2 Support for I/O disciplines
20 C<perlio> provides this, but the interface could be a lot more
23 =head2 Eliminate need for "use utf8";
25 While the C<utf8> pragma is autoloaded when necessary, it's still needed
26 for things like Unicode characters in a source file. The UTF8 hint can
27 always be set to true, but it needs to be set to false when F<utf8.pm>
28 is being compiled. (To stop Perl trying to autoload the C<utf8>
31 =head2 Autoload byte.pm
33 When the lexer sees, for instance, C<bytes::length>, it should
34 automatically load the C<bytes> pragma.
36 =head2 Make "\u{XXXX}" et al work
38 Danger, Will Robinson! Discussing the semantics of C<"\x{F00}">,
39 C<"\xF00"> and C<"\U{F00}"> on P5P I<will> lead to a long and boring
42 =head2 Overloadable regex assertions
44 This may or may not be possible with the current regular expression
45 engine. The idea is that, for instance, C<\b> needs to be
46 algorithmically computed if you're dealing with Thai text. Hence, the
47 B<\b> assertion wants to be overloaded by a function.
49 =head2 Unicode collation and normalization
51 Simon Cozens promises to work on this.
53 Collation? http://www.unicode.org/unicode/reports/tr10/
54 Normalization? http://www.unicode.org/unicode/reports/tr15/
56 =head2 Unicode case mappings
58 Case Mappings? http://www.unicode.org/unicode/reports/tr21/
60 =head2 Unicode regular expression character classes
62 They have some tricks Perl doesn't yet implement.
64 http://www.unicode.org/unicode/reports/tr18/
66 =head2 use Thread for iThreads
68 Artur Bergman's C<iThreads> module is a start on this, but needs to
71 =head2 make perl_clone optionally clone ops
73 So that pseudoforking, mod_perl, iThreads and nvi will work properly
74 (but not as efficiently) until the regex engine is fixed to be threadsafe.
76 =head2 Work out exit/die semantics for threads
78 =head2 Typed lexicals for compiler
80 =head2 Compiler workarounds for Win32
82 =head2 AUTOLOADing in the compiler
84 =head2 Fixing comppadlist when compiling
86 =head2 Cleaning up exported namespace
88 =head2 Complete signal handling
90 Add C<PERL_ASYNC_CHECK> to opcodes which loop; replace C<sigsetjmp> with
91 C<sigjmp>; check C<wait> for signal safety.
93 =head2 Out-of-source builds
95 This was done for 5.6.0, but needs reworking for 5.7.x
97 =head2 POSIX realtime support
99 POSIX 1003.1 1996 Edition support--realtime stuff: POSIX semaphores,
100 message queues, shared memory, realtime clocks, timers, signals (the
101 metaconfig units mostly already exist for these)
103 =head2 UNIX98 support
105 Reader-writer locks, realtime/asynchronous IO
109 There are non-core modules, such as C<Net::IPv6>, but these will need
110 integrating when IPv6 actually starts to really happen. See RFC 2292
113 =head2 Long double conversion
115 Floating point formatting is still causing some weird test failures.
119 Locales and Unicode interact with each other in unpleasant ways.
120 One possible solution would be to adopt/support ICU:
122 http://oss.software.ibm.com/developerworks/opensource/icu/project/
124 =head2 Thread-safe regexes
126 The regular expression engine is currently non-threadsafe.
128 =head2 Arithmetic on non-Arabic numerals
130 C<[1234567890]> aren't the only numerals any more.
132 =head2 POSIX Unicode character classes
134 ([=a=] for equivalance classes, [.ch.] for collation.)
135 These are dependent on Unicode normalization and collation.
137 =head2 Factoring out common suffices/prefices in regexps (trie optimization)
139 Currently, the user has to optimize C<foo|far> and C<foo|goo> into
140 C<f(?:oo|ar)> and C<[fg]oo> by hand; this could be done automatically.
142 =head2 Security audit shipped utilities
144 All the code we ship with Perl needs to be sensible about temporary file
145 handling, locking, input validation, and so on.
147 =head2 Custom opcodes
149 Have a way to introduce user-defined opcodes without the subroutine call
150 overhead of an XSUB; the user should be able to create PP code. Simon
151 Cozens has some ideas on this.
153 =head2 spawnvp() on Win32
155 Win32 has problems spawning processes, particularly when the arguments
156 to the child process contain spaces, quotes or tab characters.
158 =head2 DLL Versioning
160 Windows needs a way to know what version of a XS or C<libperl> DLL it's
163 =head2 Introduce @( and @)
165 C<$(> may return "foo bar baz". Unfortunately, since groups can
166 theoretically have spaces in their names, this could be one, two or
169 =head2 Floating point handling
171 C<NaN> and C<inf> support is particularly troublesome.
172 (fp_classify(), fp_class(), fp_class_d(), class(), isinf(),
173 isfinite(), finite(), isnormal(), unordered(), <ieeefp.h>,
174 <fp_class.h> (there are metaconfig units for all these) (I think),
175 fp_setmask(), fp_getmask(), fp_setround(), fp_getround()
176 (no metaconfig units yet for these). Don't forget finitel(), fp_classl(),
177 fp_class_l(), (yes, both do, unfortunately, exist), and unorderedl().)
179 As of Perl 5.6.1 is a Perl macro, Perl_isnan().
181 =head2 IV/UV preservation
183 Nicholas Clark has done a lot of work on this, but work is continuing.
184 C<+>, C<-> and C<*> work, but guards need to be in place for C<%>, C</>,
185 C<&>, C<oct>, C<hex> and C<pack>.
187 =head2 Replace pod2html with something using Pod::Parser
189 The CPAN module C<Malik::Pod::Html> may be a more suitable basis for a
190 C<pod2html> convertor; the current one duplicates the functionality
191 abstracted in C<Pod::Parser>, which makes updating the POD language
194 =head2 Automate module testing on CPAN
196 When a new Perl is being beta tested, porters have to manually grab
197 their favourite CPAN modules and test them - this should be done
200 =head2 sendmsg and recvmsg
202 We have all the other BSD socket functions but these. There are
203 metaconfig units for these functions which can be added. To avoid these
204 being new opcodes, a solution similar to the way C<sockatmark> was added
205 would be preferable. (Autoload the C<IO::whatever> module.)
207 =head2 Rewrite perlre documentation
209 The new-style patterns need full documentation, and the whole document
210 needs to be a lot clearer.
212 =head2 Convert example code to IO::Handle filehandles
214 =head2 Document Win32 choices
216 =head2 Check new modules
218 =head2 Make roffitall find pods and libs itself
220 Simon Cozens has done some work on this but it needs a rethink.
222 =head1 To do at some point
224 These are ideas that have been regularly tossed around, that most
225 people believe should be done maybe during 5.8.x
227 =head2 Remove regular expression recursion
229 Because the regular expression engine is recursive, badly designed
230 expressions can lead to lots of recursion filling up the stack. Ilya
231 claims that it is easy to convert the engine to being iterative, but
232 this has still not yet been done. There may be a regular expression
233 engine hit squad meeting at TPC5.
235 =head2 Memory leaks after failed eval
237 Perl will leak memory if you C<eval "hlagh hlagh hlagh hlagh">. This is
238 partially because it attempts to build up an op tree for that code and
239 doesn't properly free it. The same goes for non-syntactically-correct
240 regular expressions. Hugo looked into this, but decided it needed a
241 mark-and-sweep GC implementation.
243 Alan notes that: The basic idea was to extend the parser token stack
244 (C<YYSTYPE>) to include a type field so we knew what sort of thing each
245 element of the stack was. The F<<perly.c> code would then have to be
246 postprocessed to record the type of each entry on the stack as it was
247 created, and the parser patched so that it could unroll the stack
250 This is possible to do, but would be pretty messy to implement, as it
251 would rely on even more sed hackery in F<perly.fixer>.
253 =head2 pack "(stuff)*"
255 That's to say, C<pack "(sI)40"> would be the same as C<pack "sI"x40>
257 =head2 bitfields in pack
259 =head2 Cross compilation
261 Make Perl buildable with a cross-compiler. This will play havoc with
262 Configure, which needs to how how the target system will respond to
263 its tests; maybe C<microperl> will be a good starting point here.
264 (Indeed, Bart Schuller reports that he compiled up C<microperl> for
265 the Agenda PDA and it works fine.) A really big spanner in the works
266 is the bootstrapping build process of Perl: if the filesystem the
267 target systems sees is not the same what the build host sees, various
268 input, output, and (Perl) library files need to be copied back and forth.
270 =head2 Perl preprocessor / macros
272 Source filters help with this, but do not get us all the way. For
273 instance, it should be possible to implement the C<??> operator somehow;
274 source filters don't (quite) cut it.
276 =head2 Perl lexer in Perl
278 Damian Conway is planning to work on this, but it hasn't happened yet.
280 =head2 Using POSIX calls internally
282 When faced with a BSD vs. SySV -style interface to some library or
283 system function, perl's roots show in that it typically prefers the BSD
284 interface (but falls back to the SysV one). One example is getpgrp().
285 Other examples include C<memcpy> vs. C<bcopy>. There are others, mostly in
288 Mostly, this item is a suggestion for which way to start a journey into
289 an C<#ifdef> forest. It is not primarily a suggestion to eliminate any of
290 the C<#ifdef> forests.
292 POSIX calls are perhaps more likely to be portable to unexpected
293 architectures. They are also perhaps more likely to be actively
294 maintained by a current vendor. They are also perhaps more likely to be
295 available in thread-safe versions, if appropriate.
297 =head2 -i rename file when changed
299 It's only necessary to rename a file when inplace editing when the file
300 has changed. Detecting a change is perhaps the difficult bit.
302 =head2 All ARGV input should act like E<lt>E<gt>
304 =head2 Support for rerunning debugger
306 There should be a way of restarting the debugger on demand.
308 =head2 my sub foo { }
310 The basic principle is sound, but there are problems with the semantics
311 of self-referential and mutually referential lexical subs: how to
314 =head2 One-pass global destruction
316 Sweeping away all the allocated memory in one go is a laudable goal, but
317 it's difficult and in most cases, it's easier to let the memory get
320 =head2 Rewrite regexp parser
322 There has been talk recently of rewriting the regular expression parser
323 to produce an optree instead of a chain of opcodes; it's unclear whether
324 or not this would be a win.
326 =head2 Cache recently used regexps
330 for my $re (@regexps) {
334 C<qr//> already gives us a way of saving compiled regexps, but it should
335 be done automatically.
337 =head2 Re-entrant functions
339 Add configure probes for C<_r> forms of system calls and fit them to the
340 core. Unfortunately, calling conventions for these functions and not
343 =head2 Cross-compilation support
345 Bart Schuller reports that using C<microperl> and a cross-compiler, he
346 got Perl working on the Agenda PDA. However, one cannot build a full
347 Perl because Configure needs to get the results for the target platform,
350 =head2 Bit-shifting bitvectors
354 vec($v, 1000, 1) = 1;
356 One should be able to do
360 and have the 999'th bit set.
362 Currently if you try with shift bitvectors you shift the NV/UV, instead
363 of the bits in the PV. Not very logical.
365 =head2 debugger pragma
367 The debugger is implemented in Perl in F<perl5db.pl>; turning it into a
368 pragma should be easy, but making it work lexically might be more
369 difficult. Fiddling with C<$^P> would be necessary.
371 =head2 use less pragma
373 Identify areas where speed/memory tradeoffs can be made and have a hint
374 to switch between them.
376 =head2 switch structures
378 Although we have C<Switch.pm> in core, Larry points to the dormant
379 C<nswitch> and C<cswitch> ops in F<pp.c>; using these opcodes would be
382 =head2 Cache eval tree
386 =head2 Shrink opcode tables
388 =head2 Optimize away @_
390 Look at the "reification" code in C<av.c>
392 =head2 Prototypes versus indirect objects
394 Currently, indirect object syntax bypasses prototype checks.
398 HTML versions of the documentation need to be installed by default; a
399 call to C<installhtml> from C<installperl> may be all that's necessary.
401 =head2 Prototype method calls
403 =head2 Return context prototype declarations
407 =head2 Garbage collection
409 There have been persistent mumblings about putting a mark-and-sweep
410 garbage detector into Perl; Alan Burlison has some ideas about this.
414 Mark-Jason Dominus has the beginnings of one of these.
416 =head2 pack/unpack tutorial
418 Simon Cozens has the beginnings of one of these.
420 =head2 Rewrite perldoc
422 There are a few suggestions for what to do with C<perldoc>: maybe a
423 full-text search, an index function, locating pages on a particular
424 high-level subject, and so on.
426 =head2 Install .3p manpages
428 This is a bone of contention; we can create C<.3p> manpages for each
429 built-in function, but should we install them by default? Tcl does this,
430 and it clutters up C<apropos>.
432 =head2 Unicode tutorial
434 Simon Cozens promises to do this before he gets old.
436 =head2 Update POSIX.pm for 1003.1-2
438 =head2 Retargetable installation
440 Allow C<@INC> to be changed after Perl is built.
442 =head2 POSIX emulation on non-POSIX systems
444 Make C<POSIX.pm> behave as POSIXly as possible everywhere, meaning we
445 have to implement POSIX equivalents for some functions if necessary.
447 =head2 Rename Win32 headers
449 =head2 Finish off lvalue functions
451 They don't work in the debugger, and they don't work for list or hash
454 =head2 Update sprintf documentation
456 Hugo van der Sanden plans to look at this.
458 =head2 Use fchown/fchmod internally
460 This has been done in places, but needs a thorough code review.
461 Also fchdir is available in some platforms.
465 Ideas which have been discussed, and which may or may not happen.
467 =head2 ref() in list context
469 It's unclear what this should do or how to do it without breaking old
472 =head2 Make tr/// return histogram
474 There is a patch for this, but it may require Unicodification.
476 =head2 Compile to real threaded code
478 =head2 Structured types
480 =head2 Modifiable $1 et al.
482 ($x = "elephant") =~ /e(ph)/;
483 $1 = "g"; # $x = "elegant"
485 What happens if there are multiple (nested?) brackets? What if the
486 string changes between the match and the assignment?
488 =head2 Procedural interfaces for IO::*, etc.
490 Some core modules have been accused of being overly-OO. Adding
491 procedural interfaces could demystify them.
495 =head2 Attach/detach debugger from running program
497 With C<gdb>, you can attach the debugger to a running program if you
498 pass the process ID. It would be good to do this with the Perl debugger
499 on a running Perl program, although I'm not sure how it would be done.
501 =head2 Alternative RE syntax module
504 $re = Regex::Newbie->new
507 ->repeat(Regex::Newbie->class("char"),3)
513 A non-core module that would use "native" GUI to create graphical
516 =head2 foreach(reverse ...)
520 foreach (reverse @_) { ... }
522 puts C<@_> on the stack, reverses it putting the reversed version on the
523 stack, then iterates forwards. Instead, it could be special-cased to put
524 C<@_> on the stack then iterate backwards.
526 =head2 Constant function cache
528 =head2 Approximate regular expression matching
532 These items B<always> need doing:
534 =head2 Update guts documentation
536 Simon Cozens tries to do this when possible, and contributions to the
537 C<perlapi> documentation is welcome.
539 =head2 Add more tests
541 Michael Schwern will donate $500 to Yet Another Society when all core
544 =head2 Update auxiliary tools
546 The code we ship with Perl should look like good Perl 5.
548 =head1 Recently done things
550 These are things which have been on the todo lists in previous releases
551 but have recently been completed.
553 =head2 Safe signal handling
555 A new signal model went into 5.7.1 without much fanfare. Operations and
556 C<malloc>s are no longer interrupted by signals, which are handled
557 between opcodes. This means that C<PERL_ASYNC_CHECK> now actually does
558 something. However, there are still a few things that need to be done.
562 Modules which implement arrays in terms of strings, substrings or files
563 can be found on the CPAN.
567 C<Time::Hires> has been integrated into the core.
569 =head2 setitimer and getimiter
571 Adding C<Time::Hires> got us this too.
573 =head2 Testing __DIE__ hook
575 Tests have been added.
577 =head2 CPP equivalent in Perl
579 A C Yardley will probably have done this by the time you can read this.
580 This allows for a generalization of the C constant detection used in
581 building C<Errno.pm>.
583 =head2 Explicit switch statements
585 C<Switch.pm> has been integrated into the core to give you all manner of
586 C<switch...case> semantics.
594 Nick Ing-Simmons has made UTF-EBCDIC (UTR13) work with Perl.
596 EBCDIC? http://www.unicode.org/unicode/reports/tr16/
600 Although there are probably some small bugs to be rooted out, Jarkko
601 Hietaniemi has made regular expressions polymorphic between bytes and
604 =head2 perlcc to produce executable
606 C<perlcc> was recently rewritten, and can now produce standalone
609 =head2 END blocks saved in compiled output
611 =head2 Secure temporary file module
613 Tim Jenness' C<File::Temp> is now in core.
615 =head2 Integrate Time::HiRes
617 This module is now part of core.
619 =head2 Turn Cwd into XS
621 Benjamin Sugars has done this.
623 =head2 Mmap for input
625 Nick Ing-Simmons' C<perlio> supports an C<mmap> IO method.
627 =head2 Byte to/from UTF8 and UTF8 to/from local conversion
629 C<Encode> provides this.
631 =head2 Add sockatmark support
635 =head2 Mailing list archives
637 http://lists.perl.org/, http://archive.develooper.com/
641 Richard Foley has written the bug tracking system at http://bugs.perl.org/
643 =head2 Integrate MacPerl
645 Chris Nandor and Matthias Neeracher have integrated the MacPerl changes
648 =head2 Web "nerve center" for Perl
650 http://use.perl.org/ is what you're looking for.
652 =head2 Regular expression tutorial
654 C<perlretut>, provided by Mark Kvale.
656 =head2 Debugging Tutorial
658 C<perldebtut>, written by Richard Foley.
660 =head2 Integrate new modules
662 Jarkko has been integrating madly into 5.7.x
664 =head2 Integrate profiler
666 C<Devel::DProf> is now a core module.
668 =head2 Y2K error detection
670 There's a configure option to detect unsafe concatenation with "19", and
671 a CPAN module. (C<D'oh::Year>)
673 =head2 Regular expression debugger
675 While not part of core, Mark-Jason Dominus has written C<Rx> and has
676 also come up with a generalised strategy for regular expression
681 That's, uh, F<podchecker>
683 =head2 "Dynamic" lexicals
685 =head2 Cache precompiled modules
687 =head1 Deprecated Wishes
689 These are items which used to be in the todo file, but have been
690 deprecated for some reason.
692 =head2 Loop control on do{}
694 This would break old code; use C<do{{ }}> instead.
696 =head2 Lexically scoped typeglobs
698 Not needed now we have lexical IO handles.
704 Damian Conway's text formatting modules seem to be the Way To Go.
706 =head2 Generalised want()/caller())
708 =head2 Named prototypes
710 These both seem to be delayed until Perl 6.
712 =head2 Built-in globbing
714 The C<File::Glob> module has been used to replace the C<glob> function.
716 =head2 Regression tests for suidperl
718 C<suidperl> is deprecated in favour of common sense.
720 =head2 Cached hash values
722 We have shared hash keys, which perform the same job.
724 =head2 Add compression modules
726 The compression modules are a little heavy; meanwhile, Nick Clark is
727 working on experimental pragmata to do transparent decompression on
730 =head2 Reorganise documentation into tutorials/references
732 Could not get consensus on P5P about this.
734 =head2 Remove distinction between functions and operators
736 Caution: highly flammable.
738 =head2 Make XS easier to use
740 Use C<Inline> instead, or SWIG.
742 =head2 Make embedding easier to use
748 See the Perl Power Tools. (http://language.perl.com/ppt/)
750 =head2 my $Package::variable
754 =head2 "or" tests defined, not truth
756 Suggesting this on P5P B<will> cause a boring and interminable flamewar.
758 =head2 "class"-based lexicals
760 Use flyweight objects, secure hashes or, dare I say it, pseudo-hashes instead.
764 C<ByteLoader> covers this.
766 =head2 Lazy evaluation / tail recursion removal
768 C<List::Util> in core gives some of these; tail recursion removal is
769 done manually, with C<goto &whoami;>. (However, MJD has found that
770 C<goto &whoami> introduces a performance penalty, so maybe there should
771 be a way to do this after all: C<sub foo {START: ... goto START;> is