This Week on perl5-porters (31 October-6 November 2005)

This Week on perl5-porters - 31 October-6 November 2005

   This week sees consolidation on several fronts: mathoms, ops, env
   handling, futimes, sort... plus the usual assortment of bug fixes and
   enhancements.

Feedback from last week's summary

   Steve Peters remembered the history of mathoms.c in p5p dated back to
   2001 and not only June/July this year, when it came to life again.
   Also, the Configure option which was anticipated were not ready yet at
   the summary time, but it is now.

     Steve Peters patches the summary
     http://xrl.us/ib67

   Concerning Cygwin, "unlink", Win32, Yitzchak Scott-Thoennes commented
   that he was referring to the Cygwin DLL source code and not perl when
   illustrating how "unlink" in Cygwin mapped to the Windows API.

     Yitzchak Scott-Thoennes makes things clear
     http://xrl.us/ib68

More mathoms.c fallout

   The recent introduction of mathoms.c produced fallout in various
   places this week

     Gisle implements the Configure option
     http://xrl.us/ib69

     and shrinks the perl binary by 0.75%
     http://xrl.us/ib7a

     Getting C<do_exec> on Win32 back in order
     http://xrl.us/ib7b

     Getting C<perl.h> on VMS back in order
     http://xrl.us/ib7c

More on "ExtUtils::Constant"

   chromatic raised an eyebrow at Sébastien Aperghis-Tramoni's use of
   indirect object notation (current best practices these days dictating
   that one should say "Object->method" rather than "method Object".
   Nicholas Clark discovered that the patch causes a bad failure in
   "blead" due to dependency orderings, because somehow in "blead",
   "FileHandle" now requires "IO::File" which is not yet available during
   the build. Nicholas fixed it up by with some conditional "require"ing
   in patch #25927.

     The patch
     http://xrl.us/ib7d

     The patch to the patch
     http://xrl.us/ib7e

Bring out yer dead (ops)

   After running perl under "gcov", Nicholas noticed that about twenty
   ops were never hit by the test suite. It could be expected that an op
   like "pp_dump" (which exists solely to make perl dump core) would not
   be covered by the test suite, but maybe some ops should (which Dave
   Mitchell said was the case for "pp_regcmaybe" and provided a snippet
   to prove it).

   Maybe some are obsolete and could thus be chainsawed away. Rafael
   Garcia-Suarez pointed out that a certain number of ops are required
   during compilation, but are optimised away afterwards, and thus it
   would be a non-trivial effort to truly get rid of them. Although he
   thought that "pp_threadsv" and "pp_setstate" could probably be let go.

   Rafael then noted that he had written some XS code in the past that
   called some "pp_*" routines directly, and mentioned that he had
   published a module on CPAN that lets you change the interpreter
   runloop on the fly.

   This led Nicholas to think about the possibility of making the runloop
   deal with the handling of signals differently. That is, getting rid of
   the current "PERL_ASYNC_CHECK()" ("safe signals") call in the runloop,
   and merely switching to a runloop that knows how to deal with a
   signal, when a signal is encountered.

     Reported in ticket #37573
     http://xrl.us/ib7f

     Change your runloop
     http://search.cpan.org/dist/Runops-Switch/lib/Runops/Switch.pm

     Nick's second idea
     http://xrl.us/ib7g

Andy's consting

   Andy Lester consted more stuff, spotted a couple of chances to
   simplify code, and dedicated the patch to Etta James:

     The patch
     http://xrl.us/ib7h

     Etta James
     http://www.etta-james.com/

   ... and dealt with perlio.c seperately because it's so hairy:

     http://xrl.us/ib7i

   Andy also posted the switches he's using for building perl under GCC
   4.1.0 snapshots (using as many switches as possible to seek out
   doubtful code constructs).

     Bondage and discipline
     http://xrl.us/ib7j

   and also found a lovely trailing semi-colon-on-on-if bug in
   "pp_ftrowned":

     http://xrl.us/ib7k

   and yet more consting

     http://xrl.us/ib7m

   and cleaning of the x2p directory

     http://xrl.us/ib7n

DB_File patched to deal with Berkeley DB 4.4

   Paul Marquess supplied a patch to get DB_File to run with the upcoming
   4.4 release of Berkeley DB. Steve Peters applied the patch and
   Yitzchak wondered whether it was important enough to make sure it made
   its way into 5.8.8.

     http://xrl.us/ib7o

Let the good futimes roll

   Gisle Aas continued on the thread last week about using "futimes" on
   platforms where it is available, noting that the MacOS X manpage says
   that "utime" is obsolete and "utimes" should be used, but the Posix
   manpage says that "utimes" is legacy, and "utime" should be used for
   maximum portability. Sigh. Steve Peters and Gisle discussed the
   problem of getting Configure to probe for this.

   Also, Solaris 10 has a function called "futimesat", which does
   everything, and more besides. (In case you were wondering, these
   functions deal with setting the access and modification times for
   files).

     utime? utimes?
     http://xrl.us/ib7p

     Abe Timmerman patches configure.com
     http://xrl.us/ib7q

sort/multicall patch in blead

   Robin Houston's sort/multicall patch went into blead. Rafael noticed a
   few puffs of smoke escape from the lab, and saw that one functionality
   that the patch broke was the ability to empty the array *while you
   sort it* and still retrieve the results afterwards. Since no-one was
   really sure why anyone would want to do a thing like that, the test
   was quietly dropped.

   So don't try the following at home, because it's not going to work any
   more:

     @a = (1..10);
     @b = sort { @a=(); ($a+1)<=>($b+1) } @a;

   Nicholas was worried that the test was a guard to check for core
   dumps, but perl wasn't dumping core, just sorting an array of
   undefined elements (which seems to be the right behaviour under the
   circumstances).

   Paul Marquess found that "DB_File" revealed a couple of problems in
   the patch, and these problems were fixed. Jim Cromie pitched in and
   fixed a couple of other test errors.

   Dave Mitchell had a couple of minor queries about the code but
   basically liked it. The conversation went on between Robin and Dave
   for a while. Robin summed it up best:

     It's the usual perl internals story really: everything
     depends on everything else in mysterious and undocumented
     ways, and it's hard to make apparently innocent changes
     without subtle breakage...

     Starting from last week
     http://xrl.us/ib7r

     The patch applied
     http://xrl.us/ib7s

     Dave weighs in
     http://xrl.us/ib7t

Compiling 5.8.7 with Visual Studio 2005

   Joel Reed wrote in to say that he was having some difficulty in
   compiling 5.8.7 with Microsoft's latest compiler, especially in the
   area of "perlio" and related some very wacky symptoms. He also tried
   5.9.2, and that didn't work, either. And unfortunately for Joel, he
   was Warnocked.

     http://xrl.us/ib7u

The prototype of "Perl_magic_clear_all_env"

   Alan Burlison, in his quest to make the environment code a little less
   icky, wanted to change the signature of the "Perl_magic_clear_all_env"
   function. This would prevent memory leaks when one lets perl manage
   the environment.

   The main problem is whether or not this would break binary
   compatibility. Steve Peters used the CPAN source code search and found
   that no-one outside of core is using it, and thought that it is
   unlikely that any other code does so, but the possibility cannot be
   ruled out.

   Alan was worried about platforms using different calling conventions
   and decided that the best way forward would be to put the new smarts
   in a new routine, and thereby not allow the possibility of breaking
   binary compatibility.

   Alan subsequently posted a patch to make use perl use "clearenv" on
   platforms where it makes sense, and called for feedback on other
   platforms such as MacOS, Symbian, VMS and Win32.

     The question
     http://xrl.us/ib7v

     All hail gonzui
     http://cpansearch.bulknews.net/

     using clearenv
     http://xrl.us/ib7w

A surprising segfault

   Robin Houston was rather bemused by:

     % perl -e 'map print(reverse), ("")x68'
     Segmentation fault

   and wondered why it was happening. Dave Mitchell promptly described
   the problem and fixed it. Sadahiro Tomoyuki found that many other
   "pp_*" functions exhibit similar behaviour and provided a patch to fix
   them too. Tels wanted tests.

     segfault
     http://xrl.us/ib7x

     How to kill perl
     http://www.perlmonks.org/index.pl?node_id=505817

See perl say()

   Steve Peters proposed a patch to bring Perl 6's "say()" to Perl 5.
   (Which is roughly "print" with a "\n" tacked on). Robin Houston
   pointed to a prior thread (and patch) on the issue, that was not well
   received at the time. The main problem is one of backwards
   compatibility: how do you deal with a program that has defined a
   subroutine named "say"?

   (The summariser recalls a thread on Perlmonks where someone suggested
   using "-l" on the command line to get equivalent "say" functionality
   with "print" and use "printf" (not necessarily with "%" args) to get
   non-newline print behaviour).

     This time
     http://xrl.us/ib7y

     Last time around
     http://xrl.us/ib7z

New Core Module Releases

   Andreas J. Koenig brought "CPAN.pm" up to version 1.76_60. (The _60
   implies a beta version). Some of the new features include: plays
   nicely with version.pm, support for "sudo", new commands, better error
   messages and better handling of configuration variables.

Perl 5 Bug Summary

   1520 open items, six items less that 2 weeks old have not been
   responded to.

In brief

   Jarkko added UIQ support to the Symbian port

     http://xrl.us/ib72

   Steven Schubiger cleared up the no-whitespace-before-semicolon
   problems for pod files that needed it.

     http://xrl.us/ib73

   Jutta posted a bug report dealing with "sysread" in UTF-8 mode. When
   Steve Peters opined that a little bit of code might help understand
   the problem more easily, Jutta replied with a TCP server written in C
   and a client written in Perl. What more could you wish for?

     http://xrl.us/ib74

   Alan Burlison was still wondering about the "malloc_wrap" compiler
   warnings being produced. After discussing the issue with Nicholas, he
   decided to add an explanation about the compiler warnings to the
   README.solaris file.

     http://xrl.us/ib75

   Dan Dascalescu posted a bug report concerning "File::Glob", escaped
   metacharacters and spaces in filenames. Steven Schubiger showed a
   couple of ways to get around the problem.

     http://xrl.us/ib76

   Andreas J. Koenig took a stab at fixing bug #19049 (Incorrect $` after
   replacement). Rafael applied it, and then backed it out after not
   being able to solve the remaining problems himself. If someone else
   wants to have a go...

     http://xrl.us/ib77

   Robin Houston noted that perlcall.pod documents problems that were
   fixed way back in version 5.002, and fired up the chainsaw.

     http://xrl.us/ib78

   Anno Siegel posted an interesting bug:

     my $str = 'aa';
     $str &= 'a';
     $str =~ /a+$/ or die;

   This dies, and Anno says it shouldn't. No response for the moment.

     http://xrl.us/ib79

About this summary

   This summary was written by David Landgren.

   Information concerning bugs referenced in this summary (as #nnnnn) may
   be viewed at http://rt.perl.org/rt3/Ticket/Display.html?id=nnnnn

   Information concerning patches to maint or blead referenced in this
   summary (as #nnnnn) may be viewed at
   http://public.activestate.com/cgi-bin/perlbrowse?patch=nnnnn

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