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perltodo(1) - perltodo - Perl TO-DO List - man 1 perltodo

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PERLTODO(1)            Perl Programmers Reference Guide            PERLTODO(1)

       perltodo - Perl TO-DO List

       This is a list of wishes for Perl.  Send updates to  If you want to work on any of these projects,
       be sure to check the perl5-porters archives for past ideas, flames, and
       propaganda.  This will save you time(1,2,n) and also prevent you from imple-
       menting something that Larry has already vetoed.  One set(7,n,1 builtins) of archives
       may be found at:


       Clean up and finish support for assertions. See assertions.

       Sarathy and Arthur have a proposal for an improved Copy On Write which
       specifically will be able to COW new ithreads. If this can be imple-
       mented it would be a good thing.

(?{...}) closures in(1,8) regexps
       Fix (or rewrite) the implementation of the "/(?{...})/" closures.

A re-entrant regexp(3,n) engine
       This will allow the use of a regex(3,7) from inside (?{ }), (??{ }) and
       (?(?{ })|) constructs.

       lexical pragmas

       Reimplement the mechanism of lexical pragmas to be more extensible. Fix
       current pragmas that don't work well (or at all) with lexical scopes or
       in(1,8) run-time eval(STRING) ("sort(1,3)", "re", "encoding(3,n)" for example). MJD
       has a preliminary patch that implements this.

       use less(1,3) 'memory'

       Investigate trade offs to switch(1,n) out perl's choices on memory usage.
       Particularly perl should be able to give memory back.

prototypes and functions
       _ prototype character

       Study the possibility of adding a new prototype character, "_", meaning
       "this argument defaults to $_".

       inlining autoloaded constants

       Currently the optimiser can inline constants when expressed as subrou-
       tines with prototype ($) that return a constant. Likewise, many pack-
       ages wrapping C libraries export lots of constants as subroutines which
       are AUTOLOADed on demand. However, these have no prototypes, so can't
       be seen as constants by the optimiser. Some way of cheaply (low syntax,
       low memory overhead) to the perl compiler that a name is a constant
       would be great, so that it knows to call the AUTOLOAD routine at com-
       pile time(1,2,n), and then inline the constant.

       Finish off lvalue functions

       The old perltodo notes "They don't work in(1,8) the debugger, and they don't
       work for list or hash slices."

Unicode and UTF8
       Implicit Latin 1 => Unicode translation

       Conversions from byte strings to UTF-8 currently map high bit charac-
       ters to Unicode without translation (or, depending on how you look(1,8,3 Search::Dict) at
       it, by implicitly assuming that the byte strings are in(1,8) Latin-1). As
       perl assumes the C locale(3,5,7) by default, upgrading a string(3,n) to UTF-8 may
       change the meaning of its contents regarding character classes, case
       mapping, etc.  This should probably emit a warning (at least).

       UTF8 caching code

       The string(3,n) position/offset cache is not optional. It should be.

       Unicode in(1,8) Filenames

       chdir, chmod(1,2), chown(1,2), chroot(1,2), exec(3,n,1 builtins), glob(1,3,7,n), link(1,2), lstat, mkdir(1,2), open(2,3,n),
       opendir, qx, readdir(2,3), readlink(1,2), rename(1,2,n), rmdir(1,2), stat(1,2), symlink, sysopen,
       system, truncate(2,7), unlink(1,2), utime, -X.  All these could potentially
       accept(2,8) Unicode filenames either as input or output (and in(1,8) the case of
       system and qx Unicode in(1,8) general, as input or output to/from the
       shell).  Whether a filesystem - an operating system pair understands
       Unicode in(1,8) filenames varies.

       Known combinations that have some level of understanding include
       Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in(1,8) Mac OS
       X), NFS v4 is rumored to be Unicode, and of course Plan 9.  How to cre-
       ate Unicode filenames, what forms of Unicode are accepted and used
       (UCS-2, UTF-16, UTF-8), what (if(3,n) any) is the normalization form used,
       and so on, varies.  Finding the right level of interfacing to Perl
       requires some thought.  Remember that an OS does not implicate a

       (The Windows -C command flag "wide API support" has been at least tem-
       porarily retired in(1,8) 5.8.1, and the -C has been repurposed, see perl-

       Unicode in(1,8) %ENV

       Currently the %ENV entries are always byte strings.

       regexp(3,n) optimiser optional

       The regexp(3,n) optimiser is not optional. It should configurable to be, to
       allow its performance to be measured, and its bugs to be easily demon-

       common suffices/prefices in(1,8) regexps (trie optimization)

       Currently, the user has to optimize "foo|far" and "foo|goo" into
       "f(?:oo|ar)" and "[fg]oo" by hand; this could be done automatically.

       POD -> HTML conversion still sucks

       Which is crazy given just how simple POD purports to be, and how simple
       HTML can be.

Misc medium sized projects

       Introduce a new special block, UNITCHECK, which is run at the end of a
       compilation unit (module, file(1,n), eval(STRING) block). This will corre-
       spond to the Perl 6 CHECK. Perl 5's CHECK cannot be changed or removed
       because the backend framework depends on it.

       optional optimizer

       Make the peephole optimizer optional.

       You WANT *how* many

       Currently contexts are void, scalar and list. split(1,n) has a special mech-
       anism in(1,8) place to pass in(1,8) the number of return values wanted. It would
       be useful to have a general mechanism for this, backwards compatible
       and little speed hit.  This would allow proposals such as short cir-
       cuiting sort(1,3) to be implemented as a module on CPAN.

       lexical aliases

       Allow lexical aliases (maybe via the syntax "my \$alias = \$foo".

       no 6

       Make "no 6" and "no v6" work (opposite of "use 5.005", etc.).


       Clean this up. Check everything in(1,8) core works

       entersub XS vs Perl

       At the moment pp_entersub is huge, and has code to deal with entering
       both perl and and XS subroutines. Subroutine implementations rarely
       change between perl and XS at run time(1,2,n), so investigate using 2 ops to
       enter subs (one for XS, one for perl) and swap between if(3,n) a sub is

       @INC source filter(1,3x,3x curs_util) to Filter::Simple

       The second return value from a sub in(1,8) @INC can be a source filter. This
       isn't documented. It should be changed to use Filter::Simple, tested
       and documented.

       bincompat functions

       There are lots of functions which are retained for binary compatibil-
       ity.  Clean these up. Move them to mathom.c, and don't compile for

       Use fchown/fchmod internally

       The old perltodo notes "This has been done in(1,8) places, but needs a thor-
       ough code review. Also fchdir is available in(1,8) some platforms."

       Make Schwern poorer

       Tests for everything, At which point Schwern coughs up $500 to TPF.

       test B

       A test suite for the B module would be nice.

       Improve tests for doesn't appear to be well tested.

       common test code for timed bailout

       Write portable self destruct code for tests to stop them burning CPU in(1,8)
       infinite loops. Needs to avoid using alarm(1,2), as some of the tests are
       testing alarm(1,2)/sleep(1,3) or timers.

       compressed man(1,5,7) pages

       Be able to install them

       Make cope with differences between build and installed perl

       Relocatable perl

       Make it possible to create a relocatable perl binary. Will need some
       collusion with We could use a syntax of ... for location of
       current binary?

       make HTML install work

       put patchlevel in(1,8) -v

       Currently perl from p4/rsync ships with a patchlevel.h file(1,n) that usu-
       ally defines one local patch, of the form "MAINT12345" or "RC1". The
       output of perl -v doesn't report that a perl isn't an official release,
       and this information can get lost in(1,8) bugs reports. Because of this, the
       minor version(1,3,5) isn't bumped up util RC time(1,2,n), to minimise the possibility
       of versions of perl escaping that believe themselves to be newer than
       they actually are.

       It would be useful to find an elegant way to have the "this is an
       interim maintenance release" or "this is a release candidate" in(1,8) the
       terse -v output, and have it so that it's easy for the pumpking to
       remove this just as the release tarball is rolled up. This way the ver-
       sion(1,3,5) pulled out of rsync would always say "I'm a development release"
       and it would be safe to bump the reported minor version(1,3,5) as soon as a
       release ships, which would aid perl developers.

Incremental things
       Some tasks that don't need to get done in(1,8) one big hit.


       Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no

       fix tainting bugs

       Fix the bugs revealed by running the test suite with the "-t" switch(1,n)
       (via "make test.taintwarn").

       Make tainting consistent

       Tainting would be easier to use if(3,n) it didn't take documented shortcuts
       and allow taint to "leak" everywhere within an expression.

       Dual life everything

       As part of the "dists" plan, anything that doesn't belong in(1,8) the small-
       est perl distribution needs to be dual lifed. Anything else can be too.

Vague things
       Some more nebulous ideas


       Make threads more robust.

       POSIX memory footprint

       Ilya observed that use POSIX; eats memory like there's no tomorrow, and
       at various times worked to cut it down. There is probably still fat to
       cut out - for example POSIX passes Exporter some very memory hungry
       data structures.

       Optimize away @_

       The old perltodo notes "Look at the "reification" code in(1,8) "av.c""

       switch(1,n) ops

       The old perltodo notes "Although we have "" in(1,8) core, Larry
       points to the dormant "nswitch" and "cswitch" ops in(1,8) pp.c; using these
       opcodes would be much faster."

       Attach/detach debugger from running program

       The old perltodo notes "With "gdb", you can attach the debugger to a
       running program if(3,n) you pass the process ID. It would be good to do this
       with the Perl debugger on a running Perl program, although I'm not sure
       how it would be done."  ssh and screen do this with named(5,8) pipes in(1,8) tmp.
       Maybe we can too.

       A decent benchmark

       perlbench seems impervious to any recent changes made to the perl core.
       It would be useful to have a reasonable general benchmarking suite that
       roughly represented what current perl programs do, and measurably
       reported whether tweaks to the core improve, degrade or don't really
       affect performance, to guide people attempting to optimise the guts of

perl v5.8.5                       2004-04-23                       PERLTODO(1)

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