perltodo - Perl TO-DO List
This is a list of wishes for Perl. Send updates to
[email protected]. 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 and also prevent you from implementing
something that Larry has already vetoed. One set of
archives may be found at:
http://www.xray.mpe.mpg.de/mailing-
lists/perl5-porters/
assertions
Clean up and finish support for assertions. See assertions.
iCOW
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 implemented it would be a good thing.
(?{...}) closures in regexps
Fix (or rewrite) the implementation of the "/(?{...})/"
closures.
A re-entrant regexp engine [Toc] [Back] This will allow the use of a regex from inside (?{ }),
(??{ }) and (?(?{ })|) constructs.
pragmata
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 run-time eval(STRING)
("sort", "re", "encoding" for example). MJD has a preliminary
patch that implements this.
use less 'memory'
Investigate trade offs to switch 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 $_".
inlining autoloaded constants
Currently the optimiser can inline constants when
expressed as subroutines with prototype ($) that return a
constant. Likewise, many packages 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 compile time, and
then inline the constant.
Finish off lvalue functions [Toc] [Back]
The old perltodo notes "They don't work in the debugger,
and they don't work for list or hash slices."
Implicit Latin 1 => Unicode translation
Conversions from byte strings to UTF-8 currently map high
bit characters to Unicode without translation (or, depending
on how you look at it, by implicitly assuming that the
byte strings are in Latin-1). As perl assumes the C locale
by default, upgrading a string 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 [Toc] [Back]
The string position/offset cache is not optional. It
should be.
Unicode in Filenames [Toc] [Back]
chdir, chmod, chown, chroot, exec, glob, link, lstat,
mkdir, open, opendir, qx, readdir, readlink, rename,
rmdir, stat, symlink, sysopen, system, truncate, unlink,
utime, -X. All these could potentially accept Unicode
filenames either as input or output (and in the case of
system and qx Unicode in general, as input or output
to/from the shell). Whether a filesystem - an operating
system pair understands Unicode in 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 Mac OS X), NFS v4 is rumored to be Unicode,
and of course Plan 9. How to create Unicode filenames,
what forms of Unicode are accepted and used (UCS-2,
UTF-16, UTF-8), what (if 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 filesystem.
(The Windows -C command flag "wide API support" has been
at least temporarily retired in 5.8.1, and the -C has been
repurposed, see perlrun.)
Unicode in %ENV
Currently the %ENV entries are always byte strings.
regexp optimiser optional
The regexp optimiser is not optional. It should configurable
to be, to allow its performance to be measured, and
its bugs to be easily demonstrated.
common suffices/prefices in 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 [Toc] [Back] UNITCHECK
Introduce a new special block, UNITCHECK, which is run at
the end of a compilation unit (module, file, eval(STRING)
block). This will correspond to the Perl 6 CHECK. Perl 5's
CHECK cannot be changed or removed because the O.pm/B.pm
backend framework depends on it.
optional optimizer
Make the peephole optimizer optional.
You WANT *how* many
Currently contexts are void, scalar and list. split has a
special mechanism in place to pass in 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 circuiting sort
to be implemented as a module on CPAN.
lexical aliases
Allow lexical aliases (maybe via the syntax "my lias =
oo".
no 6
Make "no 6" and "no v6" work (opposite of "use 5.005",
etc.).
IPv6 [Toc] [Back]
Clean this up. Check everything in 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, so investigate using 2 ops to enter subs (one for
XS, one for perl) and swap between if a sub is redefined.
@INC source filter to Filter::Simple
The second return value from a sub in @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
compatibility. Clean these up. Move them to mathom.c, and
don't compile for blead?
Use fchown/fchmod internally
The old perltodo notes "This has been done in places, but
needs a thorough code review. Also fchdir is available in
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 Config.pm [Toc] [Back]
Config.pm 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 infinite loops. Needs to avoid using alarm,
as some of the tests are testing alarm/sleep or timers.
compressed man pages
Be able to install them
Make Config.pm cope with differences between build and [Toc] [Back]
installed perl
Relocatable perl [Toc] [Back]
Make it possible to create a relocatable perl binary. Will
need some collusion with Config.pm. We could use a syntax
of ... for location of current binary?
make HTML install work
put patchlevel in -v
Currently perl from p4/rsync ships with a patchlevel.h
file that usually 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 bugs reports. Because of this,
the minor version isn't bumped up util RC time, 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 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 version pulled
out of rsync would always say "I'm a development release"
and it would be safe to bump the reported minor version as
soon as a release ships, which would aid perl developers.
Some tasks that don't need to get done in one big hit.
autovivification
Make all autovivification consistent w.r.t LVALUE/RVALUE
and strict/no strict;
fix tainting bugs
Fix the bugs revealed by running the test suite with the
"-t" switch (via "make test.taintwarn").
Make tainting consistent [Toc] [Back]
Tainting would be easier to use if it didn't take documented
shortcuts and allow taint to "leak" everywhere
within an expression.
Dual life everything [Toc] [Back]
As part of the "dists" plan, anything that doesn't belong
in the smallest perl distribution needs to be dual lifed.
Anything else can be too.
Some more nebulous ideas
threads
Make threads more robust.
POSIX memory footprint [Toc] [Back]
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
"av.c""
switch ops
The old perltodo notes "Although we have "Switch.pm" in
core, Larry points to the dormant "nswitch" and "cswitch"
ops in 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 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 pipes in 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.
perl v5.8.5 2002-11-06 7 [ Back ] |
