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
+=head1 Tasks that only need Perl knowledge
-The roadmap to 5.10 envisages feature based releases, as various items in this
-TODO are completed.
+=head2 Remove duplication of test setup.
-=head2 Needed for the final 5.10.0 release
+Schwern notes, that there's duplication of code - lots and lots of tests have
+some variation on the big block of C<$Is_Foo> checks. We can safely put this
+into a file, change it to build an C<%Is> hash and require it. Maybe just put
+it into F<test.pl>. Throw in the handy tainting subroutines.
-Review perlguts. Significant changes have occured since 5.8, and we can't
-release a new version without making sure these are covered.
+=head2 merge common code in installperl and installman
-=head1 Tasks that only need Perl knowledge
+There are some common subroutines and a common C<BEGIN> block in F<installperl>
+and F<installman>. These should probably be merged. It would also be good to
+check for duplication in all the utility scripts supplied in the source
+tarball. It might be good to move them all to a subdirectory, but this would
+require careful checking to find all places that call them, and change those
+correctly.
=head2 common test code for timed bail out
The addition of C<Pod::Simple> and its related modules may make this task
easier to complete.
+=head2 merge checkpods and podchecker
+
+F<pod/checkpods.PL> (and C<make check> in the F<pod/> subdirectory)
+implements a very basic check for pod files, but the errors it discovers
+aren't found by podchecker. Add this check to podchecker, get rid of
+checkpods and have C<make check> use podchecker.
+
+=head2 perlmodlib.PL rewrite
+
+Currently perlmodlib.PL needs to be run from a source directory where perl
+has been built, or some modules won't be found, and others will be
+skipped. Make it run from a clean perl source tree (so it's reproducible).
+
=head2 Parallel testing
(This probably impacts much more than the core: also the Test::Harness
A full test suite for the B module would be nice.
+=head2 Deparse inlined constants
+
+Code such as this
+
+ use constant PI => 4;
+ warn PI
+
+will currently deparse as
+
+ use constant ('PI', 4);
+ warn 4;
+
+because the tokenizer inlines the value of the constant subroutine C<PI>.
+This allows various compile time optimisations, such as constant folding
+and dead code elimination. Where these haven't happened (such as the example
+above) it ought be possible to make B::Deparse work out the name of the
+original constant, because just enough information survives in the symbol
+table to do this. Specifically, the same scalar is used for the constant in
+the optree as is used for the constant subroutine, so by iterating over all
+symbol tables and generating a mapping of SV address to constant name, it
+would be possible to provide B::Deparse with this functionality.
+
=head2 A decent benchmark
C<perlbench> seems impervious to any recent changes made to the perl core. It
changes would be needed to package that module and its tests up for CPAN, and
do so. Test it with older perl releases, and fix the problems you find.
+To make a minimal perl distribution, it's useful to look at
+F<t/lib/commonsense.t>.
+
=head2 Improving C<threads::shared>
Investigate whether C<threads::shared> could share aggregates properly with
not see the same filesystem(s), the $Config{run} may need to do some
file/directory copying back and forth.
+=head2 roffitall
+
+Make F<pod/roffitall> be updated by F<pod/buildtoc>.
+
=head1 Tasks that need a little C knowledge
These tasks would need a little C knowledge, but don't need any specific
background or experience with XS, or how the Perl interpreter works
+=head2 Modernize the order of directories in @INC
+
+The way @INC is laid out by default, one cannot upgrade core (dual-life)
+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>.
+
+=head2 -Duse32bit*
+
+Natively 64-bit systems need neither -Duse64bitint nor -Duse64bitall.
+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.
+
=head2 Make it clear from -v if this is the exact official release
Currently perl from C<p4>/C<rsync> ships with a F<patchlevel.h> file that
the various OP structures from arenas. The SV arena code can probably be
re-used for this.
+Note that Configuring perl with C<-Accflags=-DPL_OP_SLAB_ALLOC> will use
+Perl_Slab_alloc() to pack optrees into a contiguous block, which is
+probably superior to the use of OP arenas, esp. from a cache locality
+standpoint. See L<Profile Perl - am I hot or not?>.
+
=head2 Improve win32/wince.c
Currently, numerous functions look virtually, if not completely,
There is also a similar issue with POSIX CRT function names like fileno having
been deprecated in favour of ISO C++ conformant names like _fileno. These
-warnings are also currently suppressed with the compiler option /wd4996. It
+warnings are also currently suppressed by adding -D_CRT_NONSTDC_NO_DEPRECATE. It
might be nice to do as Microsoft suggest here too, although, unlike the secure
functions issue, there is presumably little or no benefit in this case.
+=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 -D_FORTIFY_SOURCE=2, -fstack-protector
+
+Recent glibcs support C<-D_FORTIFY_SOURCE=2> and recent gcc
+(4.1 onwards?) supports C<-fstack-protector>, both of which give
+protection against various kinds of buffer overflow problems.
+These should probably be used for compiling Perl whenever available,
+Configure and/or hints files should be adjusted to probe for the
+availability of these features and enable them as appropriate.
+
=head1 Tasks that need a knowledge of XS
These tasks would need C knowledge, and roughly the level of knowledge of
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.
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
opendir(), closedir(), seekdir(), rewinddir(), glob(); symlink(),
readlink().
+See also L</"Virtualize operating system access">.
+
=head2 -C on the #! line
It should be possible to make -C work correctly if found on the #! line,
handle. To make it work needs some investigation of the ordering of function
calls during startup, and (by implication) a bit of tweaking of that order.
+=head2 Propagate const outwards from Perl_moreswitches()
+
+Change 32057 changed the parameter and return value of C<Perl_moreswitches()>
+from <char *> to <const char *>. It should now be possible to propagate
+const-correctness outwards to C<S_parse_body()>, C<Perl_moreswitches()>
+and C<Perl_yylex()>.
+
+=head2 Duplicate logic in S_method_common() and Perl_gv_fetchmethod_autoload()
+
+A comment in C<S_method_common> notes
+
+ /* This code tries to figure out just what went wrong with
+ gv_fetchmethod. It therefore needs to duplicate a lot of
+ the internals of that function. We can't move it inside
+ Perl_gv_fetchmethod_autoload(), however, since that would
+ cause UNIVERSAL->can("NoSuchPackage::foo") to croak, and we
+ don't want that.
+ */
+
+If C<Perl_gv_fetchmethod_autoload> gets rewritten to take (more) flag bits,
+then it ought to be possible to move the logic from C<S_method_common> to
+the "right" place. When making this change it would probably be good to also
+pass in at least the method name length, if not also pre-computed hash values
+when known. (I'm contemplating a plan to pre-compute hash values for common
+fixed strings such as C<ISA> and pass them in to functions.)
+
+=head2 Organize error messages
+
+Perl's diagnostics (error messages, see L<perldiag>) could use
+reorganizing and formalizing so that each error message has its
+stable-for-all-eternity unique id, categorized by severity, type, and
+subsystem. (The error messages would be listed in a datafile outside
+of the Perl source code, and the source code would only refer to the
+messages by the id.) This clean-up and regularizing should apply
+for all croak() messages.
+
+This would enable all sorts of things: easier translation/localization
+of the messages (though please do keep in mind the caveats of
+L<Locale::Maketext> about too straightforward approaches to
+translation), filtering by severity, and instead of grepping for a
+particular error message one could look for a stable error id. (Of
+course, changing the error messages by default would break all the
+existing software depending on some particular error message...)
+
+This kind of functionality is known as I<message catalogs>. Look for
+inspiration for example in the catgets() system, possibly even use it
+if available-- but B<only> if available, all platforms will B<not>
+have catgets().
+
+For the really pure at heart, consider extending this item to cover
+also the warning messages (see L<perllexwarn>, C<warnings.pl>).
=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 lexicals used only once
+
+This warns:
+
+ $ perl -we '$pie = 42'
+ Name "main::pie" used only once: possible typo at -e line 1.
+
+This does not:
+
+ $ perl -we 'my $pie = 42'
+
+Logically all lexicals used only once should warn, if the user asks for
+warnings. An unworked RT ticket (#5087) has been open for almost seven
+years for this discrepancy.
+
+=head2 UTF-8 revamp
+
+The handling of Unicode is unclean in many places. For example, the regexp
+engine matches in Unicode semantics whenever the string or the pattern is
+flagged as UTF-8, but that should not be dependent on an internal storage
+detail of the string. Likewise, case folding behaviour is dependent on the
+UTF8 internal flag being on or off.
+
+=head2 Properly Unicode safe tokeniser and pads.
+
+The tokeniser isn't actually very UTF-8 clean. C<use utf8;> is a hack -
+variable names are stored in stashes as raw bytes, without the utf-8 flag
+set. The pad API only takes a C<char *> pointer, so that's all bytes too. The
+tokeniser ignores the UTF-8-ness of C<PL_rsfp>, or any SVs returned from
+source filters. All this could be fixed.
+
+=head2 state variable initialization in list context
+
+Currently this is illegal:
+
+ state ($a, $b) = foo();
+
+In Perl 6, C<state ($a) = foo();> and C<(state $a) = foo();> have different
+semantics, which is tricky to implement in Perl 5 as currently they produce
+the same opcode trees. The Perl 6 design is firm, so it would be good to
+implement the necessary code in Perl 5. There are comments in
+C<Perl_newASSIGNOP()> that show the code paths taken by various assignment
+constructions involving state variables.
+
=head2 Implement $value ~~ 0 .. $range
It would be nice to extend the syntax of the C<~~> operator to also
understand numeric (and maybe alphanumeric) ranges.
+=head2 A does() built-in
+
+Like ref(), only useful. It would call the C<DOES> method on objects; it
+would also tell whether something can be dereferenced as an
+array/hash/etc., or used as a regexp, etc.
+L<http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-03/msg00481.html>
+
+=head2 Tied filehandles and write() don't mix
+
+There is no method on tied filehandles to allow them to be called back by
+formats.
+
=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 Optimize away empty destructors
+
+Defining an empty DESTROY method might be useful (notably in
+AUTOLOAD-enabled classes), but it's still a bit expensive to call. That
+could probably be optimized.
+
=head2 LVALUE functions for lists
The old perltodo notes that lvalue functions don't work for list or hash
perl and XS at run time, so investigate using 2 ops to enter subs (one for
XS, one for perl) and swap between if a sub is redefined.
-=head2 Self ties
+=head2 Self-ties
-self ties are currently illegal because they caused too many segfaults. Maybe
-the causes of these could be tracked down and self-ties on all types re-
-instated.
+Self-ties are currently illegal because they caused too many segfaults. Maybe
+the causes of these could be tracked down and self-ties on all types
+reinstated.
=head2 Optimize away @_
The old perltodo notes "Look at the "reification" code in C<av.c>".
-=head2 What hooks would assertions need?
-
-Assertions are in the core, and work. However, assertions needed to be added
-as a core patch, rather than an XS module in ext, or a CPAN module, because
-the core has no hooks in the necessary places. It would be useful to
-investigate what hooks would need to be added to make it possible to provide
-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 The yada yada yada operators
Perl 6's Synopsis 3 says:
implementation, the approaches could be merged.
What would this give us? One often-asked-for feature this would
-enable is using Unicode for filenames (and other "names" like %ENV,
-usernames, hostnames, and so forth.) But this would also allow for
-things like virtual filesystems, virtual networks, and "sandboxes"
-(though as long as dynamic loading of random object code is allowed,
-not very safe sandboxes since external code of course know not of
-Perl's vtables). An example of a smaller "sandbox" is that this
-feature can be used to implement per-thread working directories:
-Win32 already does this.
+enable is using Unicode for filenames, and other "names" like %ENV,
+usernames, hostnames, and so forth.
+(See L<perlunicode/"When Unicode Does Not Happen">.)
+
+But this kind of virtualization would also allow for things like
+virtual filesystems, virtual networks, and "sandboxes" (though as long
+as dynamic loading of random object code is allowed, not very safe
+sandboxes since external code of course know not of Perl's vtables).
+An example of a smaller "sandbox" is that this feature can be used to
+implement per-thread working directories: Win32 already does this.
+
+See also L</"Extend PerlIO and PerlIO::Scalar">.
+
+=head2 Investigate PADTMP hash pessimisation
+
+The peephole optimier converts constants used for hash key lookups to shared
+hash key scalars. Under ithreads, something is undoing this work. See
+See http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2007-09/msg00793.html
=head1 Big projects
projects / p5sagit/p5-mst-13.2.git / blobdiff