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1=head1 NAME
3perltodo - Perl TO-DO List
e50bb9a1 6
722d2a37 7This is a list of wishes for Perl. Send updates to
8I<>. If you want to work on any of these
9projects, be sure to check the perl5-porters archives for past ideas,
10flames, and propaganda. This will save you time and also prevent you
11from implementing something that Larry has already vetoed. One set
12of archives may be found at:
cd793d32 16=head1 assertions
e50bb9a1 17
cd793d32 18Clean up and finish support for assertions. See L<assertions>.
e50bb9a1 19
cd793d32 20=head1 iCOW
e50bb9a1 21
22Sarathy and Arthur have a proposal for an improved Copy On Write which
23specifically will be able to COW new ithreads. If this can be implemented
24it would be a good thing.
e50bb9a1 25
cd793d32 26=head1 (?{...}) closures in regexps
4b3b956a 27
cd793d32 28Fix (or rewrite) the implementation of the C</(?{...})/> closures.
4b3b956a 29
30=head1 A re-entrant regexp engine
32This will allow the use of a regex from inside (?{ }), (??{ }) and
33(?(?{ })|) constructs.
cd793d32 35=head1 pragmata
e50bb9a1 36
cd793d32 37=head2 lexical pragmas
0562c0e3 38
39Reimplement the mechanism of lexical pragmas to be more extensible. Fix
40current pragmas that don't work well (or at all) with lexical scopes or in
41run-time eval(STRING) (C<sort>, C<re>, C<encoding> for example). MJD has a
42preliminary patch that implements this.
0562c0e3 43
cd793d32 44=head2 use less 'memory'
f35392ae 45
46Investigate trade offs to switch out perl's choices on memory usage.
47Particularly perl should be able to give memory back.
f35392ae 48
cd793d32 49=head1 prototypes and functions
c5fc23ff 50
cd793d32 51=head2 _ prototype character
e50bb9a1 52
53Study the possibility of adding a new prototype character, C<_>, meaning
54"this argument defaults to $_".
e50bb9a1 55
cd793d32 56=head2 inlining autoloaded constants
776f8809 57
58Currently the optimiser can inline constants when expressed as subroutines
59with prototype ($) that return a constant. Likewise, many packages wrapping
60C libraries export lots of constants as subroutines which are AUTOLOADed on
61demand. However, these have no prototypes, so can't be seen as constants by
62the optimiser. Some way of cheaply (low syntax, low memory overhead) to the
63perl compiler that a name is a constant would be great, so that it knows to
64call the AUTOLOAD routine at compile time, and then inline the constant.
776f8809 65
cd793d32 66=head2 Finish off lvalue functions
e50bb9a1 67
68The old perltodo notes "They don't work in the debugger, and they don't work for
69list or hash slices."
e50bb9a1 70
cd793d32 71=head1 Unicode and UTF8
e50bb9a1 72
cd793d32 73=head2 Implicit Latin 1 => Unicode translation
e50bb9a1 74
75Conversions from byte strings to UTF-8 currently map high bit characters
76to Unicode without translation (or, depending on how you look at it, by
77implicitly assuming that the byte strings are in Latin-1). As perl assumes
78the C locale by default, upgrading a string to UTF-8 may change the
79meaning of its contents regarding character classes, case mapping, etc.
80This should probably emit a warning (at least).
e50bb9a1 81
cd793d32 82=head2 UTF8 caching code
e50bb9a1 83
cd793d32 84The string position/offset cache is not optional. It should be.
e50bb9a1 85
86=head2 Unicode in Filenames
88chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open,
89opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen,
90system, truncate, unlink, utime, -X. All these could potentially accept
91Unicode filenames either as input or output (and in the case of system
92and qx Unicode in general, as input or output to/from the shell).
93Whether a filesystem - an operating system pair understands Unicode in
94filenames varies.
96Known combinations that have some level of understanding include
97Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac
98OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to
99create Unicode filenames, what forms of Unicode are accepted and used
100(UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used,
101and so on, varies. Finding the right level of interfacing to Perl
102requires some thought. Remember that an OS does not implicate a
105(The Windows -C command flag "wide API support" has been at least
106temporarily retired in 5.8.1, and the -C has been repurposed, see
109=head2 Unicode in %ENV
111Currently the %ENV entries are always byte strings.
cd793d32 113=head1 Regexps
e50bb9a1 114
cd793d32 115=head2 regexp optimiser optional
e50bb9a1 116
117The regexp optimiser is not optional. It should configurable to be, to allow
118its performance to be measured, and its bugs to be easily demonstrated.
e50bb9a1 119
938c8732 120=head2 common suffices/prefices in regexps (trie optimization)
c47ff5f1 121
122Currently, the user has to optimize C<foo|far> and C<foo|goo> into
123C<f(?:oo|ar)> and C<[fg]oo> by hand; this could be done automatically.
e50bb9a1 124
cd793d32 125=head1 POD
e50bb9a1 126
cd793d32 127=head2 POD -> HTML conversion still sucks
e50bb9a1 128
129Which is crazy given just how simple POD purports to be, and how simple HTML
130can be.
cd793d32 132=head1 Misc medium sized projects
e50bb9a1 133
cd793d32 134=head2 UNITCHECK
e50bb9a1 135
136Introduce a new special block, UNITCHECK, which is run at the end of a
137compilation unit (module, file, eval(STRING) block). This will correspond to
138the Perl 6 CHECK. Perl 5's CHECK cannot be changed or removed because the backend framework depends on it.
e50bb9a1 140
cd793d32 141=head2 optional optimizer
e50bb9a1 142
cd793d32 143Make the peephole optimizer optional.
e50bb9a1 144
145=head2 You WANT *how* many
60cb11a8 147Currently contexts are void, scalar and list. split has a special mechanism in
148place to pass in the number of return values wanted. It would be useful to
149have a general mechanism for this, backwards compatible and little speed hit.
150This would allow proposals such as short circuiting sort to be implemented
151as a module on CPAN.
cd793d32 153=head2 lexical aliases
e50bb9a1 154
cd793d32 155Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>.
e50bb9a1 156
cd793d32 157=head2 no 6
e50bb9a1 158
cd793d32 159Make C<no 6> and C<no v6> work (opposite of C<use 5.005>, etc.).
e50bb9a1 160
cd793d32 161=head2 IPv6
3958b146 162
cd793d32 163Clean this up. Check everything in core works
e50bb9a1 164
cd793d32 165=head2 entersub XS vs Perl
e50bb9a1 166
167At the moment pp_entersub is huge, and has code to deal with entering both
168perl and and XS subroutines. Subroutine implementations rarely change between
169perl and XS at run time, so investigate using 2 ops to enter subs (one for
170XS, one for perl) and swap between if a sub is redefined.
e50bb9a1 171
cd793d32 172=head2 @INC source filter to Filter::Simple
e50bb9a1 173
174The second return value from a sub in @INC can be a source filter. This isn't
175documented. It should be changed to use Filter::Simple, tested and documented.
e50bb9a1 176
cd793d32 177=head2 bincompat functions
e50bb9a1 178
179There are lots of functions which are retained for binary compatibility.
180Clean these up. Move them to mathom.c, and don't compile for blead?
e50bb9a1 181
722d2a37 182=head2 Use fchown/fchmod internally
e50bb9a1 183
184The old perltodo notes "This has been done in places, but needs a thorough
185code review. Also fchdir is available in some platforms."
e50bb9a1 186
cd793d32 187=head1 Tests
e50bb9a1 188
cd793d32 189=head2 Make Schwern poorer
e50bb9a1 190
cd793d32 191Tests for everything, At which point Schwern coughs up $500 to TPF.
e50bb9a1 192
cd793d32 193=head2 test B
722d2a37 194
cd793d32 195A test suite for the B module would be nice.
722d2a37 196
cd793d32 197=head2 common test code for timed bailout
e50bb9a1 198
199Write portable self destruct code for tests to stop them burning CPU in
200infinite loops. Needs to avoid using alarm, as some of the tests are testing
201alarm/sleep or timers.
e50bb9a1 202
cd793d32 203=head1 Installation
e50bb9a1 204
cd793d32 205=head2 compressed man pages
e50bb9a1 206
cd793d32 207Be able to install them
e50bb9a1 208
cd793d32 209=head2 Make cope with differences between build and installed perl
e50bb9a1 210
cd793d32 211=head2 Relocatable perl
e50bb9a1 212
213Make it possible to create a relocatable perl binary. Will need some collusion
214with We could use a syntax of ... for location of current binary?
e50bb9a1 215
cd793d32 216=head2 make HTML install work
e50bb9a1 217
218=head2 put patchlevel in -v
220Currently perl from p4/rsync ships with a patchlevel.h file that usually
221defines one local patch, of the form "MAINT12345" or "RC1". The output of
222perl -v doesn't report that a perl isn't an official release, and this
223information can get lost in bugs reports. Because of this, the minor version
fa11829f 224isn't bumped up until RC time, to minimise the possibility of versions of perl
225escaping that believe themselves to be newer than they actually are.
227It would be useful to find an elegant way to have the "this is an interim
228maintenance release" or "this is a release candidate" in the terse -v output,
229and have it so that it's easy for the pumpking to remove this just as the
230release tarball is rolled up. This way the version pulled out of rsync would
231always say "I'm a development release" and it would be safe to bump the
232reported minor version as soon as a release ships, which would aid perl
cd793d32 235=head1 Incremental things
e50bb9a1 236
cd793d32 237Some tasks that don't need to get done in one big hit.
e50bb9a1 238
cd793d32 239=head2 autovivification
e50bb9a1 240
cd793d32 241Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict;
e50bb9a1 242
cd793d32 243=head2 fix tainting bugs
e50bb9a1 244
245Fix the bugs revealed by running the test suite with the C<-t> switch (via
246C<make test.taintwarn>).
e50bb9a1 247
cd793d32 248=head2 Make tainting consistent
e50bb9a1 249
250Tainting would be easier to use if it didn't take documented shortcuts and allow
251taint to "leak" everywhere within an expression.
e50bb9a1 252
253=head2 Dual life everything
255As part of the "dists" plan, anything that doesn't belong in the smallest perl
256distribution needs to be dual lifed. Anything else can be too.
cd793d32 258=head1 Vague things
e50bb9a1 259
cd793d32 260Some more nebulous ideas
e50bb9a1 261
cd793d32 262=head2 threads
e50bb9a1 263
cd793d32 264Make threads more robust.
e50bb9a1 265
cd793d32 266=head2 POSIX memory footprint
e50bb9a1 267
268Ilya observed that use POSIX; eats memory like there's no tomorrow, and at
269various times worked to cut it down. There is probably still fat to cut out -
270for example POSIX passes Exporter some very memory hungry data structures.
e50bb9a1 271
cd793d32 272=head2 Optimize away @_
f86a8bc5 273
80b46460 274The old perltodo notes "Look at the "reification" code in C<av.c>".
3298bd4d 275
cd793d32 276=head2 switch ops
3298bd4d 277
278The old perltodo notes "Although we have C<> in core, Larry points to
279the dormant C<nswitch> and C<cswitch> ops in F<pp.c>; using these opcodes would
280be much faster."
0562c0e3 281
d10fc472 282=head2 Attach/detach debugger from running program
1626a787 283
284The old perltodo notes "With C<gdb>, you can attach the debugger to a running
285program if you pass the process ID. It would be good to do this with the Perl
286debugger on a running Perl program, although I'm not sure how it would be done."
287ssh and screen do this with named pipes in tmp. Maybe we can too.
1626a787 288
289=head2 A decent benchmark
291perlbench seems impervious to any recent changes made to the perl core. It would
292be useful to have a reasonable general benchmarking suite that roughly
293represented what current perl programs do, and measurably reported whether
294tweaks to the core improve, degrade or don't really affect performance, to
295guide people attempting to optimise the guts of perl.
297=head2 readpipe(LIST)
299system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid
300running a shell. readpipe() (the function behind qx//) could be similarly