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 5.9.4 release
+
+=over
+
+=item *
+
+Implement L</state variables> (mostly done currently)
+
+=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 5.9.5 release
+
+=over
+
+=item *
+
+Implement L</_ prototype character>
+
+=item *
+
+Review smart match semantics in light of Perl 6 developments.
+
+=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
+
+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.
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>
+=head2 embed.pl/makedef.pl
-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.
+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.
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>)
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 should be done litle differently. Namely C<miniperl> should be built for
+HOST and then full C<perl> with extensions should be compiled for TARGET.
when making a tarball, yet leave the default source saying "I'm not the
official release".
-=head2 Tidy up global variables
-
-There's a note in F<intrpvar.h>
-
- /* These two variables are needed to preserve 5.8.x bincompat because
- we can't change function prototypes of two exported functions.
- Probably should be taken out of blead soon, and relevant prototypes
- changed. */
-
-So doing this, and removing any of the unused variables still present would
-be good.
-
=head2 Ordering of "global" variables.
F<thrdvar.h> and F<intrpvarh> define the "global" variables that need to be
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.
-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>.
+=head2 Profile Perl - am I hot or not?
-=head2 emulate the per-thread memory pool on Unix
+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.
-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.
+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.
-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
+Except that it's not clear if these really are the most commonly used ops. So
+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>.
- 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 */
- };
+=head2 Shrink struct context
+In F<cop.h>, we have
-although C<long double> might not be the only type to add to the padding
-union.
+ struct context {
+ U32 cx_type; /* what kind of context this is */
+ union {
+ struct block cx_blk;
+ struct subst cx_subst;
+ } cx_u;
+ };
-=head2 reduce duplication in sv_setsv_flags
+There are less than 256 values for C<cx_type>, and the constituent parts
+C<struct block> and C<struct subst> both contain some C<U8> and C<U16> fields,
+so it should be possible to move them to the first word, and share space with
+a C<U8> C<cx_type>, saving 1 word.
-C<Perl_sv_setsv_flags> has a comment
-C</* There's a lot of redundancy below but we're going for speed here */>
+=head2 Allocate OPs from arenas
-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?
+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
the perl API that comes from writing modules that use XS to interface to
C.
-=head2 IPv6
-
-Clean this up. Check everything in core works
-
-=head2 shrink C<GV>s, C<CV>s
-
-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.
+=head2 shrink C<PVBM>s
-=head2 merge Perl_sv_2[inpu]v
-
-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>
-
-=head2 UTF8 caching code
-
-The string position/offset cache is not optional. It should be.
+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 Implicit Latin 1 => Unicode translation
=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.
+Document the new support for lexical pragmas in 5.9.3 and how %^H works.
+Maybe C<re>, C<encoding>, maybe other pragmas could be made lexical.
=head2 Attach/detach debugger from running program
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
Study the possibility of adding a new prototype character, C<_>, meaning
"this argument defaults to $_".
-=head2 @INC source filter to Filter::Simple
+=head2 state variables
-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.
+C<my $foo if 0;> is deprecated, and should be replaced with
+C<state $x = "initial value\n";> the syntax from Perl 6.
+Rafael has sent a first cut patch to perl5-porters.
=head2 regexp optimiser optional
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.
+=head2 Integrate Russ Allbery's strlcat/strlcpy implementation
-
-
+And remove the last remaining uses of strcat() and strcpy(). Also, add
+my_strlcat() and my_strlcpy() to Devel::PPPort so previous versions of Perl can
+use these APIs.
=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
projects / p5sagit/p5-mst-13.2.git / blobdiff