This is a live mirror of the Perl 5 development currently hosted at https://github.com/perl/perl5
Finding a way to put "I'm MAINT" in perl -v is a TODO
[perl5.git] / pod / perltodo.pod
CommitLineData
7711098a
GS
1=head1 NAME
2
3perltodo - Perl TO-DO List
4
5=head1 DESCRIPTION
e50bb9a1 6
722d2a37 7This is a list of wishes for Perl. Send updates to
e50bb9a1
GS
8I<perl5-porters@perl.org>. 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:
13
14 http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/
15
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
cd793d32
NC
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
cd793d32 30=head1 pragmata
e50bb9a1 31
cd793d32 32=head2 lexical pragmas
0562c0e3 33
cd793d32
NC
34Reimplement the mechanism of lexical pragmas to be more extensible. Fix
35current pragmas that don't work well (or at all) with lexical scopes or in
36run-time eval(STRING) (C<sort>, C<re>, C<encoding> for example). MJD has a
37preliminary patch that implements this.
0562c0e3 38
cd793d32 39=head2 use less 'memory'
f35392ae 40
cd793d32
NC
41Investigate trade offs to switch out perl's choices on memory usage.
42Particularly perl should be able to give memory back.
f35392ae 43
cd793d32 44=head1 prototypes and functions
c5fc23ff 45
cd793d32 46=head2 _ prototype character
e50bb9a1 47
cd793d32
NC
48Study the possibility of adding a new prototype character, C<_>, meaning
49"this argument defaults to $_".
e50bb9a1 50
cd793d32 51=head2 inlining autoloaded constants
776f8809 52
cd793d32
NC
53Currently the optimiser can inline constants when expressed as subroutines
54with prototype ($) that return a constant. Likewise, many packages wrapping
55C libraries export lots of constants as subroutines which are AUTOLOADed on
56demand. However, these have no prototypes, so can't be seen as constants by
57the optimiser. Some way of cheaply (low syntax, low memory overhead) to the
58perl compiler that a name is a constant would be great, so that it knows to
59call the AUTOLOAD routine at compile time, and then inline the constant.
776f8809 60
cd793d32 61=head2 Finish off lvalue functions
e50bb9a1 62
cd793d32
NC
63The old perltodo notes "They don't work in the debugger, and they don't work for
64list or hash slices."
e50bb9a1 65
cd793d32 66=head1 Unicode and UTF8
e50bb9a1 67
cd793d32 68=head2 Implicit Latin 1 => Unicode translation
e50bb9a1 69
cd793d32
NC
70Conversions from byte strings to UTF-8 currently map high bit characters
71to Unicode without translation (or, depending on how you look at it, by
72implicitly assuming that the byte strings are in Latin-1). As perl assumes
73the C locale by default, upgrading a string to UTF-8 may change the
74meaning of its contents regarding character classes, case mapping, etc.
75This should probably emit a warning (at least).
e50bb9a1 76
cd793d32 77=head2 UTF8 caching code
e50bb9a1 78
cd793d32 79The string position/offset cache is not optional. It should be.
e50bb9a1 80
938c8732
NC
81=head2 Unicode in Filenames
82
83chdir, chmod, chown, chroot, exec, glob, link, lstat, mkdir, open,
84opendir, qx, readdir, readlink, rename, rmdir, stat, symlink, sysopen,
85system, truncate, unlink, utime, -X. All these could potentially accept
86Unicode filenames either as input or output (and in the case of system
87and qx Unicode in general, as input or output to/from the shell).
88Whether a filesystem - an operating system pair understands Unicode in
89filenames varies.
90
91Known combinations that have some level of understanding include
92Microsoft NTFS, Apple HFS+ (In Mac OS 9 and X) and Apple UFS (in Mac
93OS X), NFS v4 is rumored to be Unicode, and of course Plan 9. How to
94create Unicode filenames, what forms of Unicode are accepted and used
95(UCS-2, UTF-16, UTF-8), what (if any) is the normalization form used,
96and so on, varies. Finding the right level of interfacing to Perl
97requires some thought. Remember that an OS does not implicate a
98filesystem.
99
100(The Windows -C command flag "wide API support" has been at least
101temporarily retired in 5.8.1, and the -C has been repurposed, see
102L<perlrun>.)
103
104=head2 Unicode in %ENV
105
106Currently the %ENV entries are always byte strings.
107
cd793d32 108=head1 Regexps
e50bb9a1 109
cd793d32 110=head2 regexp optimiser optional
e50bb9a1 111
cd793d32
NC
112The regexp optimiser is not optional. It should configurable to be, to allow
113its performance to be measured, and its bugs to be easily demonstrated.
e50bb9a1 114
938c8732 115=head2 common suffices/prefices in regexps (trie optimization)
c47ff5f1 116
722d2a37
SC
117Currently, the user has to optimize C<foo|far> and C<foo|goo> into
118C<f(?:oo|ar)> and C<[fg]oo> by hand; this could be done automatically.
e50bb9a1 119
cd793d32 120=head1 POD
e50bb9a1 121
cd793d32 122=head2 POD -> HTML conversion still sucks
e50bb9a1 123
938c8732
NC
124Which is crazy given just how simple POD purports to be, and how simple HTML
125can be.
126
cd793d32 127=head1 Misc medium sized projects
e50bb9a1 128
cd793d32 129=head2 UNITCHECK
e50bb9a1 130
cd793d32
NC
131Introduce a new special block, UNITCHECK, which is run at the end of a
132compilation unit (module, file, eval(STRING) block). This will correspond to
133the Perl 6 CHECK. Perl 5's CHECK cannot be changed or removed because the
134O.pm/B.pm backend framework depends on it.
e50bb9a1 135
cd793d32 136=head2 optional optimizer
e50bb9a1 137
cd793d32 138Make the peephole optimizer optional.
e50bb9a1 139
cd793d32 140=head2 lexical aliases
e50bb9a1 141
cd793d32 142Allow lexical aliases (maybe via the syntax C<my \$alias = \$foo>.
e50bb9a1 143
cd793d32 144=head2 no 6
e50bb9a1 145
cd793d32 146Make C<no 6> and C<no v6> work (opposite of C<use 5.005>, etc.).
e50bb9a1 147
cd793d32 148=head2 IPv6
3958b146 149
cd793d32 150Clean this up. Check everything in core works
e50bb9a1 151
cd793d32 152=head2 entersub XS vs Perl
e50bb9a1 153
cd793d32
NC
154At the moment pp_entersub is huge, and has code to deal with entering both
155perl and and XS subroutines. Subroutine implementations rarely change between
156perl and XS at run time, so investigate using 2 ops to enter subs (one for
157XS, one for perl) and swap between if a sub is redefined.
e50bb9a1 158
cd793d32 159=head2 @INC source filter to Filter::Simple
e50bb9a1 160
cd793d32
NC
161The second return value from a sub in @INC can be a source filter. This isn't
162documented. It should be changed to use Filter::Simple, tested and documented.
e50bb9a1 163
cd793d32 164=head2 bincompat functions
e50bb9a1 165
cd793d32
NC
166There are lots of functions which are retained for binary compatibility.
167Clean these up. Move them to mathom.c, and don't compile for blead?
e50bb9a1 168
722d2a37 169=head2 Use fchown/fchmod internally
e50bb9a1 170
cd793d32
NC
171The old perltodo notes "This has been done in places, but needs a thorough
172code review. Also fchdir is available in some platforms."
e50bb9a1 173
cd793d32 174=head2 foreach reverse
e50bb9a1 175
cd793d32
NC
176The old perltodo notes that we could optimise foreach to iterate in reverse.
177(instead of making a reversed copy on the stack)
e50bb9a1 178
cd793d32 179=head1 Tests
e50bb9a1 180
cd793d32 181=head2 Make Schwern poorer
e50bb9a1 182
cd793d32 183Tests for everything, At which point Schwern coughs up $500 to TPF.
e50bb9a1 184
cd793d32 185=head2 test B
722d2a37 186
cd793d32 187A test suite for the B module would be nice.
722d2a37 188
cd793d32 189=head2 Improve tests for Config.pm
e50bb9a1 190
cd793d32 191Config.pm doesn't appear to be well tested.
e50bb9a1 192
cd793d32 193=head2 common test code for timed bailout
e50bb9a1 194
cd793d32
NC
195Write portable self destruct code for tests to stop them burning CPU in
196infinite loops. Needs to avoid using alarm, as some of the tests are testing
197alarm/sleep or timers.
e50bb9a1 198
cd793d32 199=head1 Installation
e50bb9a1 200
cd793d32 201=head2 compressed man pages
e50bb9a1 202
cd793d32 203Be able to install them
e50bb9a1 204
cd793d32 205=head2 Make Config.pm cope with differences between build and installed perl
e50bb9a1 206
cd793d32 207=head2 Relocatable perl
e50bb9a1 208
cd793d32
NC
209Make it possible to create a relocatable perl binary. Will need some collusion
210with Config.pm. We could use a syntax of ... for location of current binary?
e50bb9a1 211
cd793d32 212=head2 make HTML install work
e50bb9a1 213
89007cb3
NC
214=head2 put patchlevel in -v
215
216Currently perl from p4/rsync ships with a patchlevel.h file that usually
217defines one local patch, of the form "MAINT12345" or "RC1". The output of
218perl -v doesn't report that a perl isn't an official release, and this
219information can get lost in bugs reports. Because of this, the minor version
220isn't bumped up util RC time, to minimise the possibility of versions of perl
221escaping that believe themselves to be newer than they actually are.
222
223It would be useful to find an elegant way to have the "this is an interim
224maintenance release" or "this is a release candidate" in the terse -v output,
225and have it so that it's easy for the pumpking to remove this just as the
226release tarball is rolled up. This way the version pulled out of rsync would
227always say "I'm a development release" and it would be safe to bump the
228reported minor version as soon as a release ships, which would aid perl
229developers.
230
cd793d32 231=head1 Incremental things
e50bb9a1 232
cd793d32 233Some tasks that don't need to get done in one big hit.
e50bb9a1 234
cd793d32 235=head2 autovivification
e50bb9a1 236
cd793d32 237Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict;
e50bb9a1 238
cd793d32 239=head2 fix tainting bugs
e50bb9a1 240
cd793d32
NC
241Fix the bugs revealed by running the test suite with the C<-t> switch (via
242C<make test.taintwarn>).
e50bb9a1 243
cd793d32 244=head2 Make tainting consistent
e50bb9a1 245
cd793d32
NC
246Tainting would be easier to use if it didn't take documented shortcuts and allow
247taint to "leak" everywhere within an expression.
e50bb9a1 248
969e704b
NC
249=head2 Dual life everything
250
251As part of the "dists" plan, anything that doesn't belong in the smallest perl
252distribution needs to be dual lifed. Anything else can be too.
253
cd793d32 254=head1 Vague things
e50bb9a1 255
cd793d32 256Some more nebulous ideas
e50bb9a1 257
cd793d32 258=head2 threads
e50bb9a1 259
cd793d32 260Make threads more robust.
e50bb9a1 261
cd793d32 262=head2 POSIX memory footprint
e50bb9a1 263
cd793d32
NC
264Ilya observed that use POSIX; eats memory like there's no tomorrow, and at
265various times worked to cut it down. There is probably still fat to cut out -
266for example POSIX passes Exporter some very memory hungry data structures.
e50bb9a1 267
cd793d32 268=head2 Optimize away @_
f86a8bc5 269
cd793d32 270The old perltodo notes "Look at the "reification" code in C<av.c>"
3298bd4d 271
cd793d32 272=head2 switch ops
3298bd4d 273
cd793d32
NC
274The old perltodo notes "Although we have C<Switch.pm> in core, Larry points to
275the dormant C<nswitch> and C<cswitch> ops in F<pp.c>; using these opcodes would
276be much faster."
0562c0e3 277
cd793d32 278** Attach/detach debugger from running program
1626a787 279
cd793d32
NC
280The old perltodo notes "With C<gdb>, you can attach the debugger to a running
281program if you pass the process ID. It would be good to do this with the Perl
282debugger on a running Perl program, although I'm not sure how it would be done."
283ssh and screen do this with named pipes in tmp. Maybe we can too.
1626a787 284