F<AUTHORS> file, which ships in the official distribution. How many other
programming languages offer you 1 line of immortality?
+=head1 The roadmap to 5.10
+The roadmap to 5.10 envisages feature based releases, as various items in this
+TODO are completed.
+
+=head2 Needed for a 5.9.5 release
+
+=over
+
+=item *
+
+Review smart match semantics in light of Perl 6 developments.
+
+=item *
+
+Review assertions. Review syntax to combine assertions. Assertions could take
+advantage of the lexical pragmas work. L</What hooks would assertions need?>
+
+=item *
+
+C<encoding> should be turned into a lexical pragma (probably).
+
+=back
+
+=head2 Needed for a 5.9.6 release
+
+Stabilisation. If all goes well, this will be the equivalent of a 5.10-beta.
=head1 Tasks that only need Perl knowledge
errors. See also L</make HTML install work>, as the layout of installation tree
is needed to improve the cross-linking.
+The addition of C<Pod::Simple> and its related modules may make this task
+easier to complete.
+
+=head2 Parallel testing
+
+(This probably impacts much more than the core: also the Test::Harness
+and TAP::* modules on CPAN.)
+
+The core regression test suite is getting ever more comprehensive, which has
+the side effect that it takes longer to run. This isn't so good. Investigate
+whether it would be feasible to give the harness script the B<option> of
+running sets of tests in parallel. This would be useful for tests in
+F<t/op/*.t> and F<t/uni/*.t> and maybe some sets of tests in F<lib/>.
+
+Questions to answer
+
+=over 4
+
+=item 1
+
+How does screen layout work when you're running more than one test?
+
+=item 2
+
+How does the caller of test specify how many tests to run in parallel?
+
+=item 3
+
+How do setup/teardown tests identify themselves?
+
+=back
+
+Pugs already does parallel testing - can their approach be re-used?
+
=head2 Make Schwern poorer
-We should have for everything. When all the core's modules are tested,
+We should have tests for everything. When all the core's modules are tested,
Schwern has promised to donate to $500 to TPF. We may need volunteers to
hold him upside down and shake vigorously in order to actually extract the
cash.
-See F<t/lib/1_compile.t> for the 3 remaining modules that need tests.
-
=head2 Improve the coverage of the core tests
-Use Devel::Cover to ascertain the core's test coverage, then add tests that
-are currently missing.
+Use Devel::Cover to ascertain the core modules's test coverage, then add
+tests that are currently missing.
=head2 test B
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.
-=head2 Refactor C<xsubpp> to be a thin wrapper around C<ExtUtils::ParseXS>
-
-C<ExtUtils::ParseXS> encapsulates a version of the C<xsubpp> into a module.
-In effect this is a code fork, and it's likely that C<xsubpp> has had some
-bug fixes since the code from C<ExtUtils::ParseXS> was derived. It would be
-good to merge the differences in, reduce down to 1 canonical implementation,
-and convert C<xsubpp> to a very thin command line wrapper to
-C<ExtUtils::ParseXS>.
-
-In theory this needs no real C knowledge, as one way of approaching this task
-is to ensure that C<ExtUtils::ParseXS> generates identical output to C<xsubpp>
-for input XS files, which does not require understanding the contents of the
-output C file. However, some C knowledge is likely to help with testing, and
-locating/producing comprehensive test cases.
-
-
-
-
+=head2 embed.pl/makedef.pl
+There is a script F<embed.pl> that generates several header files to prefix
+all of Perl's symbols in a consistent way, to provide some semblance of
+namespace support in C<C>. Functions are declared in F<embed.fnc>, variables
+in F<interpvar.h> and F<thrdvar.h>. Quite a few of the functions and variables
+are conditionally declared there, using C<#ifdef>. However, F<embed.pl>
+doesn't understand the C macros, so the rules about which symbols are present
+when is duplicated in F<makedef.pl>. Writing things twice is bad, m'kay.
+It would be good to teach C<embed.pl> to understand the conditional
+compilation, and hence remove the duplication, and the mistakes it has caused.
=head1 Tasks that need a little sysadmin-type knowledge
Or if you prefer, tasks that you would learn from, and broaden your skills
base...
-=head2 Relocatable perl
-
-The C level patches needed to create a relocatable perl binary are done, as
-is the work on F<Config.pm>. All that's left to do is the C<Configure> tweaking
-to let people specify how they want to do the install.
-
=head2 make HTML install work
There is an C<installhtml> target in the Makefile. It's marked as
as
=item substr EXPR,OFFSET,LENGTH,REPLACEMENT
-
=item substr EXPR,OFFSET,LENGTH
-
=item substr EXPR,OFFSET
and different parameter lists having different meanings. (eg C<select>)
coverage, and have C<Configure> and the F<Makefile> do all the right things
automatically.
-=head2 Make Config.pm cope with differences between build and installed perl
+=head2 Make Config.pm cope with differences between built and installed perl
Quite often vendors ship a perl binary compiled with their (pay-for)
compilers. People install a free compiler, such as gcc. To work out how to
a binary distribution better describes the installed machine, when the
installed machine differs from the build machine in some significant way.
-=head2 make parallel builds work
-
-Currently parallel builds (such as C<make -j3>) don't work reliably. We believe
-that this is due to incomplete dependency specification in the F<Makefile>.
-It would be good if someone were able to track down the causes of these
-problems, so that parallel builds worked properly.
-
=head2 linker specification files
Some platforms mandate that you provide a list of a shared library's external
export list is correct, and to build a perl that does not pollute the global
namespace with private symbols.
+=head2 Cross-compile support
+Currently C<Configure> understands C<-Dusecrosscompile> option. This option
+arranges for building C<miniperl> for TARGET machine, so this C<miniperl> is
+assumed then to be copied to TARGET machine and used as a replacement of full
+C<perl> executable.
+This could be done little differently. Namely C<miniperl> should be built for
+HOST and then full C<perl> with extensions should be compiled for TARGET.
+This, however, might require extra trickery for %Config: we have one config
+first for HOST and then another for TARGET.
=head1 Tasks that need a little C knowledge
to review the ordering of the variables, to see how much alignment padding can
be removed.
-=head2 bincompat functions
+It's also worth checking that all variables are actually used. Perl 5.8.0
+shipped with C<PL_nrs> still defined in F<thrdvar.h>, despite it being unused
+since a change over a year earlier. Had this been spotted before release, it
+could have been removed, but now it has to remain in the 5.8.x releases to
+keep the structure the same size, to retain binary compatibility.
-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?
+It's probably worth checking if all need to be the types they are. For example
-=head2 am I hot or not?
+ PERLVAR(Ierror_count, I32) /* how many errors so far, max 10 */
-The idea of F<pp_hot.c> is that it contains the I<hot> ops, the ops that are
-most commonly used. The idea is that by grouping them, their object code will
-be adjacent in the executable, so they have a greater chance of already being
-in the CPU cache (or swapped in) due to being near another op already in use.
+might work as well if stored in a signed (or unsigned) 8 bit value, if the
+comment is accurate. C<PL_multi_open> and C<PL_multi_close> can probably
+become C<char>s. Finding variables to downsize coupled with rearrangement
+could shrink the interpreter structure; a size saving which is multiplied by
+the number of threads running.
+
+=head2 Profile Perl - am I hot or not?
+
+The Perl source code is stable enough that it makes sense to profile it,
+identify and optimise the hotspots. It would be good to measure the
+performance of the Perl interpreter using free tools such as cachegrind,
+gprof, and dtrace, and work to reduce the bottlenecks they reveal.
+
+As part of this, the idea of F<pp_hot.c> is that it contains the I<hot> ops,
+the ops that are most commonly used. The idea is that by grouping them, their
+object code will be adjacent in the executable, so they have a greater chance
+of already being in the CPU cache (or swapped in) due to being near another op
+already in use.
Except that it's not clear if these really are the most commonly used ops. So
-anyone feeling like exercising their skill with coverage and profiling tools
-might want to determine what ops I<really> are the most commonly used. And in
-turn suggest evictions and promotions to achieve a better F<pp_hot.c>.
+as part of exercising your skills with coverage and profiling tools you might
+want to determine what ops I<really> are the most commonly used. And in turn
+suggest evictions and promotions to achieve a better F<pp_hot.c>.
-=head2 emulate the per-thread memory pool on Unix
+=head2 Allocate OPs from arenas
-For Windows, ithreads allocates memory for each thread from a separate pool,
-which it discards at thread exit. It also checks that memory is free()d to
-the correct pool. Neither check is done on Unix, so code developed there won't
-be subject to such strictures, so can harbour bugs that only show up when the
-code reaches Windows.
+Currently all new OP structures are individually malloc()ed and free()d.
+All C<malloc> implementations have space overheads, and are now as fast as
+custom allocates so it would both use less memory and less CPU to allocate
+the various OP structures from arenas. The SV arena code can probably be
+re-used for this.
-It would be good to be able to optionally emulate the Window pool system on
-Unix, to let developers who only have access to Unix, or want to use
-Unix-specific debugging tools, check for these problems. To do this would
-involve figuring out how the C<PerlMem_*> macros wrap C<malloc()> access, and
-providing a layer that records/checks the identity of the thread making the
-call, and recording all the memory allocated by each thread via this API so
-that it can be summarily free()d at thread exit. One implementation idea
-would be to increase the size of allocation, and store the C<my_perl> pointer
-(to identify the thread) at the start, along with pointers to make a linked
-list of blocks for this thread. To avoid alignment problems it would be
-necessary to do something like
+=head2 Improve win32/wince.c
- union memory_header_padded {
- struct memory_header {
- void *thread_id; /* For my_perl */
- void *next; /* Pointer to next block for this thread */
- } data;
- long double padding; /* whatever type has maximal alignment constraint */
- };
+Currently, numerous functions look virtually, if not completely,
+identical in both C<win32/wince.c> and C<win32/win32.c> files, which can't
+be good.
+=head1 Tasks that need a knowledge of XS
-although C<long double> might not be the only type to add to the padding
-union.
+These tasks would need C knowledge, and roughly the level of knowledge of
+the perl API that comes from writing modules that use XS to interface to
+C.
-=head2 reduce duplication in sv_setsv_flags
+=head2 shrink C<PVBM>s
-C<Perl_sv_setsv_flags> has a comment
-C</* There's a lot of redundancy below but we're going for speed here */>
+By removing unused elements and careful re-ordering, the structures for C<AV>s,
+C<HV>s, C<CV>s and C<GV>s have recently been shrunk considerably. C<PVIO>s
+probably aren't worth it, as typical programs don't use more than 8, and
+(at least) C<Filter::Util::Call> uses C<SvPVX>/C<SvCUR>/C<SvLEN> on a C<PVIO>,
+so it would mean code changes to modules on CPAN. C<PVBM>s might have some
+savings to win.
-Whilst this was true 10 years ago, the growing disparity between RAM and CPU
-speeds mean that the trade offs have changed. In addition, the duplicate code
-adds to the maintenance burden. It would be good to see how much of the
-redundancy can be pruned, particular in the less common paths. (Profiling
-tools at the ready...). For example, why does the test for
-"Can't redefine active sort subroutine" need to occur in two places?
+=head2 autovivification
+Make all autovivification consistent w.r.t LVALUE/RVALUE and strict/no strict;
+This task is incremental - even a little bit of work on it will help.
+=head2 Unicode in Filenames
-=head1 Tasks that need a knowledge of XS
+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.
-These tasks would need C knowledge, and roughly the level of knowledge of
-the perl API that comes from writing modules that use XS to interface to
-C.
+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.
-=head2 IPv6
+(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
+L<perlrun>.)
-Clean this up. Check everything in core works
+=head2 Unicode in %ENV
-=head2 shrink C<GV>s, C<CV>s
+Currently the %ENV entries are always byte strings.
+
+=head2 use less 'memory'
+
+Investigate trade offs to switch out perl's choices on memory usage.
+Particularly perl should be able to give memory back.
-By removing unused elements and careful re-ordering, the structures for C<AV>s
-and C<HV>s have recently been shrunk considerably. It's probable that the same
-approach would find savings in C<GV>s and C<CV>s, if not all the other
-larger-than-C<PVMG> types.
+This task is incremental - even a little bit of work on it will help.
-=head2 merge Perl_sv_2[inpu]v
+=head2 Re-implement C<:unique> in a way that is actually thread-safe
-There's a lot of code shared between C<Perl_sv_2iv_flags>,
-C<Perl_sv_2uv_flags>, C<Perl_sv_2nv>, and C<Perl_sv_2pv_flags>. It would be
-interesting to see if some of it can be merged into common shared static
-functions. In particular, C<Perl_sv_2uv_flags> started out as a cut&paste
-from C<Perl_sv_2iv_flags> around 5.005_50 time, and it may be possible to
-replace both with a single function that returns a value or union which is
-split out by the macros in F<sv.h>
+The old implementation made bad assumptions on several levels. A good 90%
+solution might be just to make C<:unique> work to share the string buffer
+of SvPVs. That way large constant strings can be shared between ithreads,
+such as the configuration information in F<Config>.
-=head2 UTF8 caching code
+=head2 Make tainting consistent
-The string position/offset cache is not optional. It should be.
+Tainting would be easier to use if it didn't take documented shortcuts and
+allow taint to "leak" everywhere within an expression.
-=head2 Implicit Latin 1 => Unicode translation
+=head2 readpipe(LIST)
-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).
+system() accepts a LIST syntax (and a PROGRAM LIST syntax) to avoid
+running a shell. readpipe() (the function behind qx//) could be similarly
+extended.
-This task is incremental - even a little bit of work on it will help.
+=head2 strcat(), strcpy(), strncat(), strncpy(), sprintf(), vsprintf()
+
+Maybe create a utility that checks after each libperl.a creation that
+none of the above (nor sprintf(), vsprintf(), or *SHUDDER* gets())
+ever creep back to libperl.a.
+
+ nm libperl.a | ./miniperl -alne '$o = $F[0] if /:$/; print "$o $F[1]" if $F[0] eq "U" && $F[1] =~ /^(?:strn?c(?:at|py)|v?sprintf|gets)$/'
+
+Note, of course, that this will only tell whether B<your> platform
+is using those naughty interfaces.
+
+=head2 Audit the code for destruction ordering assumptions
+
+Change 25773 notes
+
+
+=head2 Allocate OPs from arenas
+
+Currently all new OP structures are individually malloc()ed and free()d.
+All C<malloc> implementations have space overheads, and are now as fast as
+custom allocates so it would both use less memory and less CPU to allocate
+the various OP structures from arenas. The SV arena code can probably be
+re-used for this.
+
+=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
+be good.
+
+=head1 Tasks that need a knowledge of XS
+
+These tasks would need C knowledge, and roughly the level of knowledge of
+the perl API that comes from writing modules that use XS to interface to
+C.
+
+=head2 shrink C<PVBM>s
+
+By removing unused elements and careful re-ordering, the structures for C<AV>s,
+C<HV>s, C<CV>s and C<GV>s have recently been shrunk considerably. C<PVIO>s
+probably aren't worth it, as typical programs don't use more than 8, and
+(at least) C<Filter::Util::Call> uses C<SvPVX>/C<SvCUR>/C<SvLEN> on a C<PVIO>,
+so it would mean code changes to modules on CPAN. C<PVBM>s might have some
+savings to win.
=head2 autovivification
running a shell. readpipe() (the function behind qx//) could be similarly
extended.
+=head2 strcat(), strcpy(), strncat(), strncpy(), sprintf(), vsprintf()
+
+Maybe create a utility that checks after each libperl.a creation that
+none of the above (nor sprintf(), vsprintf(), or *SHUDDER* gets())
+ever creep back to libperl.a.
+ nm libperl.a | ./miniperl -alne '$o = $F[0] if /:$/; print "$o $F[1]" if $F[0] eq "U" && $F[1] =~ /^(?:strn?c(?:at|py)|v?sprintf|gets)$/'
+Note, of course, that this will only tell whether B<your> platform
+is using those naughty interfaces.
+=head2 Audit the code for destruction ordering assumptions
+
+Change 25773 notes
+
+ /* Need to check SvMAGICAL, as during global destruction it may be that
+ AvARYLEN(av) has been freed before av, and hence the SvANY() pointer
+ is now part of the linked list of SV heads, rather than pointing to
+ the original body. */
+ /* FIXME - audit the code for other bugs like this one. */
+
+adding the C<SvMAGICAL> check to
+
+ if (AvARYLEN(av) && SvMAGICAL(AvARYLEN(av))) {
+ MAGIC *mg = mg_find (AvARYLEN(av), PERL_MAGIC_arylen);
+
+Go through the core and look for similar assumptions that SVs have particular
+types, as all bets are off during global destruction.
=head1 Tasks that need a knowledge of the interpreter
These tasks would need C knowledge, and knowledge of how the interpreter works,
or a willingness to learn.
-=head2 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) (C<sort>, C<re>, C<encoding> for example). MJD has a
-preliminary patch that implements this.
-
=head2 Attach/detach debugger from running program
The old perltodo notes "With C<gdb>, you can attach the debugger to a running
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.
-=head2 inlining autoloaded constants
-
-Currently the optimiser can inline constants when expressed as subroutines
-with prototype ($) that return a constant. Likewise, many packages wrapping
-C libraries export lots of constants as subroutines which are AUTOLOADed on
-demand. However, these have no prototypes, so can't be seen as constants by
-the optimiser. Some way of cheaply (low syntax, low memory overhead) to the
-perl compiler that a name is a constant would be great, so that it knows to
-call the AUTOLOAD routine at compile time, and then inline the constant.
-
-=head2 Constant folding
-
-The peephole optimiser should trap errors during constant folding, and give
-up on the folding, rather than bailing out at compile time. It is quite
-possible that the unfoldable constant is in unreachable code, eg something
-akin to C<$a = 0/0 if 0;>
-
=head2 LVALUE functions for lists
The old perltodo notes that lvalue functions don't work for list or hash
The old perltodo notes that lvalue functions don't work in the debugger. This
would be good to fix.
-=head2 _ prototype character
-
-Study the possibility of adding a new prototype character, C<_>, meaning
-"this argument defaults to $_".
-
-=head2 @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.
-
=head2 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.
-=head2 UNITCHECK
+=head2 delete &function
-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.
+Allow to delete functions. One can already undef them, but they're still
+in the stash.
+
+=head2 Make readpipe overridable
+
+so we can override qx// as well.
=head2 optional optimizer
The old perltodo notes "Look at the "reification" code in C<av.c>".
-=head2 switch ops
-
-The old perltodo notes "Although we have C<Switch.pm> in core, Larry points to
-the dormant C<nswitch> and C<cswitch> ops in F<pp.c>; using these opcodes would
-be much faster."
-
=head2 What hooks would assertions need?
Assertions are in the core, and work. However, assertions needed to be added
the full assertion support from a CPAN module, so that we aren't constraining
the imagination of future CPAN authors.
+=head2 Properly Unicode safe tokeniser and pads.
-
-
-
-
+The tokeniser isn't actually very UTF-8 clean. C<use utf8;> is a hack -
+variable names are stored in stashes as raw bytes, without the utf-8 flag
+set. The pad API only takes a C<char *> pointer, so that's all bytes too. The
+tokeniser ignores the UTF-8-ness of C<PL_rsfp>, or any SVs returned from
+source filters. All this could be fixed.
=head1 Big projects
=head2 make ithreads more robust
-Generally make ithreads more robust. See also L<iCOW>
+Generally make ithreads more robust. See also L</iCOW>
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.
+
=head2 iCOW
Sarathy and Arthur have a proposal for an improved Copy On Write which
This will allow the use of a regex from inside (?{ }), (??{ }) and
(?(?{ })|) constructs.
+
+=head2 Add (?YES) (?NO) to regexp enigne
+
+YES/NO would allow a subpattern to be passed/failed but allow backtracking.
+Basically a more efficient (?=), (?!).
+
+demerphq has this on his todo list
+
+=head2 Add (?SUCCEED) (?FAIL) to regexp engine
+
+SUCCEED/FAIL would allow a pattern to be passed/failed but without backtracking.
+Thus you could signal that a pattern has matched or not, and return (regardless
+that there is more pattern following).
+
+demerphq has this on his todo list
+
+=head2 Add (?CUT) (?COMMIT) to regexp engine
+
+CUT would allow a pattern to say "do not backtrack beyond here".
+COMMIT would say match from here or don't, but don't try the pattern from
+another starting pattern.
+
+These correspond to the \v and \V that Jeffrey Friedl mentions in
+Mastering Regular Expressions 2nd edition.
+
+demerphq has this on his todo list
+
+=head2 Add class set operations to regexp engine
+
+Apparently these are quite useful. Anyway, Jeffery Friedl wants them.
+
+demerphq has this on his todo list, but right at the bottom.
+
+
projects / p5sagit/p5-mst-13.2.git / blobdiff