=head1 DESCRIPTION
This is a list of wishes for Perl. The most up to date version of this file
-is at http://perl5.git.perl.org/perl.git/blob_plain/HEAD:/pod/perltodo.pod
+is at L<http://perl5.git.perl.org/perl.git/blob_plain/HEAD:/pod/perltodo.pod>
The tasks we think are smaller or easier are listed first. Anyone is welcome
to work on any of these, but it's a good idea to first contact
Whilst patches to make the list shorter are most welcome, ideas to add to
the list are also encouraged. Check the perl5-porters archives for past
-ideas, and any discussion about them. One set of archives may be found at:
-
- http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/
+ideas, and any discussion about them. One set of archives may be found at
+L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/>
What can we offer you in return? Fame, fortune, and everlasting glory? Maybe
not, but if your patch is incorporated, then we'll add your name to the
=head2 Migrate t/ from custom TAP generation
Many tests below F<t/> still generate TAP by "hand", rather than using library
-functions. As explained in L<perlhack/Writing a test>, tests in F<t/> are
+functions. As explained in L<perlhack/TESTING>, tests in F<t/> are
written in a particular way to test that more complex constructions actually
work before using them routinely. Hence they don't use C<Test::More>, but
instead there is an intentionally simpler library, F<t/test.pl>. However,
quite a few tests in F<t/> have not been refactored to use it. Refactoring
any of these tests, one at a time, is a useful thing TODO.
-=head2 Test that regen.pl was run
-
-There are various generated files shipped with the perl distribution, for
-things like header files generate from data. The generation scripts are
-written in perl, and all can be run by F<regen.pl>. However, because they're
-written in perl, we can't run them before we've built perl. We can't run them
-as part of the F<Makefile>, because changing files underneath F<make> confuses
-it completely, and we don't want to run them automatically anyway, as they
-change files shipped by the distribution, something we seek not do to.
-
-If someone changes the data, but forgets to re-run F<regen.pl> then the
-generated files are out of sync. It would be good to have a test in
-F<t/porting> that checks that the generated files are in sync, and fails
-otherwise, to alert someone before they make a poor commit. I suspect that this
-would require adapting the scripts run from F<regen.pl> to have dry-run
-options, and invoking them with these, or by refactoring them into a library
-that does the generation, which can be called by the scripts, and by the test.
+The subdirectories F<base>, F<cmd> and F<comp>, that contain the most
+basic tests, should be excluded from this task.
=head2 Automate perldelta generation
The addition of C<Pod::Simple> and its related modules may make this task
easier to complete.
-=head2 Make ExtUtils::ParseXS use strict;
-
-F<lib/ExtUtils/ParseXS.pm> contains this line
-
- # use strict; # One of these days...
-
-Simply uncomment it, and fix all the resulting issues :-)
-
-The more practical approach, to break the task down into manageable chunks, is
-to work your way though the code from bottom to top, or if necessary adding
-extra C<{ ... }> blocks, and turning on strict within them.
-
=head2 Make Schwern poorer
We should have tests for everything. When all the core's modules are tested,
=head2 Improve the coverage of the core tests
-Use Devel::Cover to ascertain the core modules's test coverage, then add
+Use Devel::Cover to ascertain the core modules' test coverage, then add
tests that are currently missing.
=head2 test B
To make a minimal perl distribution, it's useful to look at
F<t/lib/commonsense.t>.
-=head2 Move dual-life pod/*.PL into ext
-
-Nearly all the dual-life modules have been moved to F<ext>. However, we
-still need to move F<pod/*.PL> into their respective directories
-in F<ext/>. They're referenced by (at least) C<plextract> in F<Makefile.SH>
-and C<utils> in F<win32/Makefile> and F<win32/makefile.ml>, and listed
-explicitly in F<win32/pod.mak>, F<vms/descrip_mms.template> and F<utils.lst>
-
=head2 POSIX memory footprint
Ilya observed that use POSIX; eats memory like there's no tomorrow, and at
told is something Perl is good at. So it would be nice to know what it is doing
that is taking so much CPU, and where possible address it.
-=head2 enable lexical enabling/disabling of inidvidual warnings
+=head2 enable lexical enabling/disabling of individual warnings
Currently, warnings can only be enabled or disabled by category. There
are times when it would be useful to quash a single warning, not a
whole category.
+=head2 document diagnostics
+
+Many diagnostic messages are not currently documented. The list is at the end
+of t/porting/diag.t.
+
=head1 Tasks that need a little sysadmin-type knowledge
Or if you prefer, tasks that you would learn from, and broaden your skills
=item *
do a normal C<Configure>, but include Devel::Cover as a module to install
-(see F<INSTALL> for how to do this)
+(see L<INSTALL> for how to do this)
=item *
F<makedef.pl> to support this format, and to provide a means within
C<Configure> to enable it. This would allow Unix users to test that the
export list is correct, and to build a perl that does not pollute the global
-namespace with private symbols.
+namespace with private symbols, and will fail in the same way as msvc or mingw
+builds or when using PERL_DL_NONLAZY=1.
=head2 Cross-compile support
Windows Perl or whether we go in a separate direction and make it so. Of
course, we all know what step 3 is.
-=head2 decouple -g and -DDEBUGGING
-
-Currently F<Configure> automatically adds C<-DDEBUGGING> to the C compiler
-flags if it spots C<-g> in the optimiser flags. The pre-processor directive
-C<DEBUGGING> enables F<perl>'s command line C<-D> options, but in the process
-makes F<perl> slower. It would be good to disentangle this logic, so that
-C-level debugging with C<-g> and Perl level debugging with C<-D> can easily
-be enabled independently.
-
=head1 Tasks that need a little C knowledge
These tasks would need a little C knowledge, but don't need any specific
modules without overwriting files. This causes problems for binary
package builders. One possible proposal is laid out in this
message:
-L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-04/msg02380.html>.
+L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-04/msg02380.html>
=head2 -Duse32bit*
On these systems, it might be the default compilation mode, and there
is currently no guarantee that passing no use64bitall option to the
Configure process will build a 32bit perl. Implementing -Duse32bit*
-options would be nice for perl 5.12.
+options would be nice for perl 5.14.
=head2 Profile Perl - am I hot or not?
=head2 Improve win32/wince.c
Currently, numerous functions look virtually, if not completely,
-identical in both C<win32/wince.c> and C<win32/win32.c> files, which can't
+identical in both F<win32/wince.c> and F<win32/win32.c> files, which can't
be good.
=head2 Use secure CRT functions when building with VC8 on Win32
not actually be writable if access is indeed denied by DACLs).
For the chdir() issue, see ActiveState bug #74552:
-http://bugs.activestate.com/show_bug.cgi?id=74552
+L<http://bugs.activestate.com/show_bug.cgi?id=74552>
Therefore, DACLs should be checked both for consistency across CRTs and for
the correct answer.
Another option could be deconstructing the implementation of some simpler
functions in op.c.
+=head2 Allow XSUBs to inline themselves as OPs
+
+For a simple XSUB, often the subroutine dispatch takes more time than the
+XSUB itself. The tokeniser already has the ability to inline constant
+subroutines - it would be good to provide a way to inline other subroutines.
+
+Specifically, simplest approach looks to be to allow an XSUB to provide an
+alternative implementation of itself as a custom OP. A new flag bit in
+C<CvFLAGS()> would signal to the peephole optimiser to take an optree
+such as this:
+
+ b <@> leave[1 ref] vKP/REFC ->(end)
+ 1 <0> enter ->2
+ 2 <;> nextstate(main 1 -e:1) v:{ ->3
+ a <2> sassign vKS/2 ->b
+ 8 <1> entersub[t2] sKS/TARG,1 ->9
+ - <1> ex-list sK ->8
+ 3 <0> pushmark s ->4
+ 4 <$> const(IV 1) sM ->5
+ 6 <1> rv2av[t1] lKM/1 ->7
+ 5 <$> gv(*a) s ->6
+ - <1> ex-rv2cv sK ->-
+ 7 <$> gv(*x) s/EARLYCV ->8
+ - <1> ex-rv2sv sKRM*/1 ->a
+ 9 <$> gvsv(*b) s ->a
+
+perform the symbol table lookup of C<rv2cv> and C<gv(*x)>, locate the
+pointer to the custom OP that provides the direct implementation, and re-
+write the optree something like:
+
+ b <@> leave[1 ref] vKP/REFC ->(end)
+ 1 <0> enter ->2
+ 2 <;> nextstate(main 1 -e:1) v:{ ->3
+ a <2> sassign vKS/2 ->b
+ 7 <1> custom_x -> 8
+ - <1> ex-list sK ->7
+ 3 <0> pushmark s ->4
+ 4 <$> const(IV 1) sM ->5
+ 6 <1> rv2av[t1] lKM/1 ->7
+ 5 <$> gv(*a) s ->6
+ - <1> ex-rv2cv sK ->-
+ - <$> ex-gv(*x) s/EARLYCV ->7
+ - <1> ex-rv2sv sKRM*/1 ->a
+ 8 <$> gvsv(*b) s ->a
+
+I<i.e.> the C<gv(*)> OP has been nulled and spliced out of the execution
+path, and the C<entersub> OP has been replaced by the custom op.
+
+This approach should provide a measurable speed up to simple XSUBs inside
+tight loops. Initially one would have to write the OP alternative
+implementation by hand, but it's likely that this should be reasonably
+straightforward for the type of XSUB that would benefit the most. Longer
+term, once the run-time implementation is proven, it should be possible to
+progressively update ExtUtils::ParseXS to generate OP implementations for
+some XSUBs.
+
=head2 Remove the use of SVs as temporaries in dump.c
F<dump.c> contains debugging routines to dump out the contains of perl data
of things like C<malloc> corruption that that currently offers us)
For more information see the thread starting with this message:
-http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2008-03/msg00305.html
+L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2008-03/msg00305.html>
=head2 autovivification
Currently glob patterns and filenames returned from File::Glob::glob()
are always byte strings. See L</"Virtualize operating system access">.
-=head2 Unicode and lc/uc operators
-
-Some built-in operators (C<lc>, C<uc>, etc.) behave differently, based on
-what the internal encoding of their argument is. That should not be the
-case. Maybe add a pragma to switch behaviour.
-
=head2 use less 'memory'
Investigate trade offs to switch out perl's choices on memory usage.
These tasks would need C knowledge, and knowledge of how the interpreter works,
or a willingness to learn.
+=head2 forbid labels with keyword names
+
+Currently C<goto keyword> "computes" the label value:
+
+ $ perl -e 'goto print'
+ Can't find label 1 at -e line 1.
+
+It is controversial if the right way to avoid the confusion is to forbid
+labels with keyword names, or if it would be better to always treat
+bareword expressions after a "goto" as a label and never as a keyword.
+
=head2 truncate() prototype
The prototype of truncate() is currently C<$$>. It should probably
Currently C<$foo ~~ $object> will die with the message "Smart matching a
non-overloaded object breaks encapsulation". It would be nice to allow
-to bypass this by using explictly the syntax C<$foo ~~ %$object> or
+to bypass this by using explicitly the syntax C<$foo ~~ %$object> or
C<$foo ~~ @$object>.
=head2 error reporting of [$a ; $b]
C<{}> used as a hashref, C<[]> or C<()>) it issues an error something like
I<';' isn't legal inside an expression - if you need multiple statements use a
do {...} block>. See the thread starting at
-http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2008-09/msg00573.html
+L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2008-09/msg00573.html>
=head2 lexicals used only once
=head2 UTF-8 revamp
-The handling of Unicode is unclean in many places. For example, the regexp
-engine matches in Unicode semantics whenever the string or the pattern is
-flagged as UTF-8, but that should not be dependent on an internal storage
-detail of the string. Likewise, case folding behaviour is dependent on the
-UTF8 internal flag being on or off.
+The handling of Unicode is unclean in many places. In the regex engine
+there are especially many problems. The swash data structure could be
+replaced my something better. Inversion lists and maps are likely
+candidates. The whole Unicode database could be placed in-core for a
+huge speed-up. Only minimal work was done on the optimizer when utf8
+was added, with the result that the synthetic start class often will
+fail to narrow down the possible choices when given non-Latin1 input.
=head2 Properly Unicode safe tokeniser and pads.
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.
-=head2 delete &function
-
-Allow to delete functions. One can already undef them, but they're still
-in the stash.
-
=head2 C</w> regex modifier
That flag would enable to match whole words, and also to interpolate
do { local $"='|'; /\b(?:P)\b/ }
-See L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-01/msg00400.html>
+See
+L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-01/msg00400.html>
for the discussion.
=head2 optional optimizer
This has actually already been implemented (but only for Win32),
take a look at F<iperlsys.h> and F<win32/perlhost.h>. While all Win32
variants go through a set of "vtables" for operating system access,
-non-Win32 systems currently go straight for the POSIX/UNIX-style
+non-Win32 systems currently go straight for the POSIX/Unix-style
system/library call. Similar system as for Win32 should be
implemented for all platforms. The existing Win32 implementation
probably does not need to survive alongside this proposed new
The peephole optimiser converts constants used for hash key lookups to shared
hash key scalars. Under ithreads, something is undoing this work.
-See http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-09/msg00793.html
+See
+L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-09/msg00793.html>
=head2 Store the current pad in the OP slab allocator
have to actually "allocate" the ops in reverse-execution order to get them
contiguous in memory in execution order.
-See http://www.nntp.perl.org/group/perl.perl5.porters/2007/12/msg131975.html
+See
+L<http://www.nntp.perl.org/group/perl.perl5.porters/2007/12/msg131975.html>
Note that running this copy, and then freeing all the old location ops would
cause their slabs to be freed, which would eliminate possible memory wastage if
be done 1st in XS, and using B::Generate to patch the new OP into the
optrees.
+=head2 Add C<00dddd>
+
+It has been proposed that octal constants be specifiable through the syntax
+C<0oddddd>, parallel to the existing construct to specify hex constants
+C<0xddddd>
+
=head1 Big projects
Tasks that will get your name mentioned in the description of the "Highlights
-of 5.12"
+of 5.14"
=head2 make ithreads more robust
This task is incremental - even a little bit of work on it will help, and
will be greatly appreciated.
-One bit would be to write the missing code in sv.c:Perl_dirp_dup.
+One bit would be to determine how to clone directory handles on systems
+without a C<fchdir> function (in sv.c:Perl_dirp_dup).
Fix Perl_sv_dup, et al so that threads can return objects.
Fix (or rewrite) the implementation of the C</(?{...})/> closures.
-=head2 A re-entrant regexp engine
-
-This will allow the use of a regex from inside (?{ }), (??{ }) and
-(?(?{ })|) constructs.
-
=head2 Add class set operations to regexp engine
Apparently these are quite useful. Anyway, Jeffery Friedl wants them.
https://perl5.git.perl.org / perl5.git / blobdiff