This Week on perl5-porters (25 September-1 October 2006)

This Week on perl5-porters - 25 September-1 October 2006

   "Well not since that time you thought that embedding perl was a good
   idea in the first place" -- Johnathon Stowe, commenting on Marc
   Lehmann saying that yes, he loved embedding perl in other applications
   and that no, he didn't do drugs.

Topics of Interest

Wrapping up EVAL handling in blead's regexp engine

   Dave Mitchell checked in a couple of patches to fix the breakage that
   had crept in during the recent overhaul to the regexp engine. Yves
   Orton liked what he saw, and suggested a few ways to improve the
   maintainability.

   Dave told him to go for it. And so he did.

     Mad scientists at work
     http://xrl.us/r4us

pod errors in "perlref.pod"

   David Landgren noticed some formatting errors when looking at
   "perlref" in blead. Rafael Garcia-Suarez wondered what podlator was
   being used, since the pod checked out as valid. The podlator in
   question was the bundled "Pod::Perldoc", which led David to wonder why
   something like Russ Alberry's podlators code. Russ explained what was
   holding this up.

     http://xrl.us/r4ut

Nick Ing-Simmons

   It was with great sadness that the porters learnt that Nick
   Ing-Simmons had died of a heart attack. Nick was one of the longest
   serving contributors to Perl's development, and we are all poorer for
   his loss. I can recall many a time when people puzzled over things
   were done in a particular way in the code, until Nick would chip in
   with a a cogent explanation of why. It will be harder without him.

     http://xrl.us/r4uu
     http://xrl.us/r4uv

   The Perl Foundation ran the following obituary

     Thanks Nick
     http://news.perl-foundation.org/2006/09/thanks_nick.html

Unhandled exceptions in shared libraries

   Kalpana Shetty explained a problem with shared libraries throwing an
   exception, and the perl program dumping core on a "SIGABRT" signal. No
   takers, possibly since the exact nature of the shared library wasn't
   specified.

     http://xrl.us/r4uw

"reentr" reshuffle

   Jarkko Hietaniemi looked at bug #40256 and a few other bits and
   pieces, and rejigged reentr.pl to make everyone happy. In fact, Marc
   Lehmann was positively ecstatic.

     Get down
     http://xrl.us/r4ux

seek beyond length

   Juerd Waalboer wanted to know whether it was reasonable to seek, upon
   a scalar opened for IO, beyond its length. And especially what happens
   as a result. Dave Mitchell confirmed that Bad Things were indeed
   happening, that probably should be fixed.

     oops
     http://xrl.us/r4uy

   I think that this may be what inspired Jarkko to file cook up the
   following patch:

     Don't talk to strangers
     http://xrl.us/r4uz

Finding the *correct* line number

   Curtis "Ovid" Poe wanted to disambiguate two calls to a function on
   the same line with "caller". Dave Mitchell mentioned that he had
   proposed to spend two bytes per op, which, at the expense of a certain
   increase in memory consumption, would clear these sorts of problems
   up, once and for all.

     http://xrl.us/r4u2

Fixing up "lndir" to improve source tree symlinking

   Jim Cromie made a small change to "lndir" to make it behave more
   nicely in the presence of modified files (which could other clobber
   the pristine base tree). This kicked off a discussion with John
   Peacock, Rafael Garcia-Suarez and Andy Dougherty about other tricks
   that can be used to deal with similar sorts of home experiments.

     http://xrl.us/r4u3

Error message changes in "blead"

   Yves Orton mourned the passing of pseudo-hashes, and their attendant
   "Can't coerce array into hash" error message. Nicholas Clark reasoned
   that it should be possible to change the current "Not a HASH
   reference" to something like "can't coerce ARRAY reference to HASH
   reference", but wondered if it would break anything.

   Yves pointed out that since the message had already changed, the issue
   was moot. Nicholas agreed that an error message should explain *why*
   something was wrong, rather than just saying that it *was* wrong.

     http://xrl.us/r4u4

   One may assume that afterwards, Yves went away to see what could be
   done to improve the situation, and came back with a new conclusion:
   perl's error message suck. They are scattered throughout the source,
   which makes maintenance difficult, and localisation impossible. He
   proposed changing things like

           DIE(aTHX_ "Not a GLOB reference");

   to

           THROW_ERROR(PERL_ENOTAGLOB);

   This way, a message can be changed in one single place, and would
   allow commercial vendors to make perl's error message fit in with
   their own frameworks (witness the recent z/OS efforts), and finally
   allow messages to be translated in to other languages.

   Jonathan Stowe wasn't exactly opposed to the idea, but mentioned the
   frequent idiom:

     eval { somethingnasty() };
     $@ and $@ =~ /Some nasty error/ and recover();

   Rafael pointed out that there are messages with %s specifiers as well,
   but that it would surely benefit the maintenance of "perldiag".

     Globales Symbol "x" erfordert ausdrücklichen Paketnamen
     http://xrl.us/r4u5

Patches of Interest

What Yves Orton did this week

   Nicholas applied Yves's patch from last week, which prompted Yves to
   deliver another patch, this time sawing off six thread-shared
   variables. The result is that "use re 'debug'" is now lexically
   scoped. This latter patch was redone after Rafael had a bit of trouble
   with it. Yves also took the opportunity to throw in some tests for
   lexically scoped regexp debugging.

     Awesome
     http://xrl.us/r4u6

   On to the main course, Yves then delivered a patch that introduced a
   new assertion that allows the writing of elegant expressions to match
   arbitrarily deeply nested pairs of tokens. For instance, one could
   parse XML documents code with:

     /^(<(?:[^<>]+|(?1))*>)$/

   (along with the appropriate amount of hand waving). Yves was critical
   of the implementation, in that it requires capturing "(...)" to be
   used, rather than grouping "(?:...)", but on the other hand it
   conforms with what Python and PCRE already do.

   Dave Mitchell was most impressed, and quizzed Yves about the
   behavioural semantics regarding backtracking. Rafael wanted to know if
   it was possible to extend the patch to allow case sensitivity changes
   by way of something like "(?i(?1))". (Alas, no).

   Robin Houston also expressed his delight at the patch and admitted to
   being the party who added this functionality to PCRE since he lacked
   the courage to attack Perl's regular expression internals. He too
   raised a couple of questions about behaviour in borderline areas.

   Yves followed up with another version of the patch that added user
   documentation and more tests. He has also been reading Jeffrey
   Friedl's *Mastering Regular Expressions*, and has taken up the
   challenge to resolve as much as possible the areas in which Jeffrey
   finds Perl's regular expressions wanting. He laid out his roadmap in
   "perltodo".

   All applied.

     And the crowd goes wild
     http://xrl.us/r4u7

   And as Yves was sweeping the floor of the lab clean from his previous
   efforts, he bundled up one last patch to tidy the regexp debugging
   output somewhat.

     http://xrl.us/r4u8

Improving "Exporter" documentation

   Smylers caught up on the Exporter thread (thanks to the summary, heh)
   and argued in favour of ensuring that code was "strict"-compatible,
   even if "use strict" wasn't explicitly mentioned in the snippet. This
   means either using package variables or using "our".

     http://xrl.us/r4u9

Continuing to deal with some gcc warnings

   Sadahiro Tomoyuki figured out why a recent patch of Jarkko's was
   causing things to go boom! on a perl compiled with "-Duse64bitint".
   Patched.

     http://xrl.us/r4va

"File::Temp" doesn't handle "cmp" overloading

   Rafael Garcia-Suarez posted a short snippet demonstrating a problem
   with "File::Temp" overloading. When stringified (interpolated in a
   string), a "File::Temp" object returns the underlying file name.

   This works fine until you try to compare the stringified object to a
   scalar, at which point perl starts looking for an "eq" operator and
   dies. So the fix was to overload "cmp", and all was well, but Rafael
   wondered whether "overload" should synthesise a "cmp" from a
   stringification override.

   Rick Delaney pointed out that it will already do this if you add the
   "fallback => 1" attribute. John Peacock didn't like the idea of
   generating "cmp" automatically.

     http://xrl.us/r4vb

cflags.SH: The Revenge of "gcc -std=c89"

   Jarkko, ever the optimist, kicked through the rubble of his previous
   C89 configuration patch and worked up a scan to get better results
   back to see how "-ansi", "-pedantic" and "-std=c89" behave in the face
   of weird system headers and other platform oddities, and asked for
   people on proprietary hardware to take it for a spin and see what
   comes of it.

     Don't take no for an answer
     http://xrl.us/r4vc

New and old bugs from RT

threads creation memory leak (#40416)

   Santeri Paavolainen posted a short program that demonstrated a fairly
   definite leak when creating threads. Dave Mitchell noted that it was
   fixed in blead.

     Another reason
     http://xrl.us/r4vd

"File::Find" has issues with symlinks (#40417)

   Ammon posted a very long and detailed report about the problems that
   "File::Find" has in relation to symbolic links. Code included.

     Warnocked
     http://xrl.us/r4ve

Unicode Command Line Arguments (#40418)

   Dale Gerdermann wanted to read Unicode arguments from the command line
   and it seemed to work in all cases until he hit a regular expression,
   and there he had to force a "utf8::upgrade($arg)" for it to work.

   Dave Mitchell pointed the "-C" command line switch that takes care of
   this issue.

     http://xrl.us/r4vf

   Dale found similar Unicode problems in conjunction with LWP and
   Unicode (#40432)

     http://xrl.us/r4vg

"XML-Twig" tests cause "bleadperl" to segfault (#40420)

   Shlomi Fish reported that the test suite of "XML-Twig" version 3.26
   causes segfaults on "bleadperl", but forgot to say which tests were at
   fault.

     http://xrl.us/r4vh

Segfault in pack (#40427)

   dgay showed how to provoke a core dump with a simple call to "pack"
   and provided a simple patch to fix up the problem. Unapplied.

     Should have a test, too
     http://xrl.us/r4vi

Perl5 Bug Summary

     A net increase of ten bugs this week
     http://xrl.us/r4vj

     Kill a bug today
     http://rt.perl.org/rt3/NoAuth/perl5/Overview.html

New Core Modules

   *   Andreas König released CPAN 1.88_51 to CPAN.

         http://xrl.us/r4vk

In Brief

   Dave Mitchell applied an expedient hack to allow "\x{NNN}" in
   t/op/re_tests.

     So there's no excuse now
     http://xrl.us/r4vm

   Mark Stosberg wanted to clarify the documentation for lib.pm with a
   short snippet. H.Merijn Brand golfed it.

     And still readable
     http://xrl.us/r4vn

   David Landgren made a small clarification in "perlref" concerning the
   interpolation of scalar references.

     http://xrl.us/r4vo

   Christian Jaeger made a couple of suggestions to improve the
   navigation between "bugs.perl.org", Request Tracker and CPAN.

     http://xrl.us/r4vp

   Jim Cromie wanted to start cooking with "perl.gcov", so Steve Peters
   and Sébastien Aperghis-Tramoni gave him a couple of recipes.

     Got you covered
     http://xrl.us/r4vq

   John E. Malmberg. responsible in large part for brings Perl's VMS
   implementation kicking and screaming into the third millennium, had to
   say goodbye for now. He's out looking for a new job, and so had to bow
   out from the list for the time being.

     Thanks, and good luck
     http://xrl.us/r4vr

   Yves Orton noticed that the ptree constants TODO tests are passing and
   wondered if that meant that they could be untodo'ed.

     http://xrl.us/r4vs

   Jim Cromie proposed a "-U" patch, that stands for Unofficial
   Userhacking.

     http://xrl.us/r4vt

   Jarkko thought that gcc's "-pedantic" should be renamed "-useless".

     http://xrl.us/r4vu

About this summary

   This summary was written by David Landgren.

   Weekly summaries are published on http://use.perl.org/ and posted on a
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   archive is at http://dev.perl.org/perl5/list-summaries/. Corrections
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-- 
hope still, a little resistance always maybe stubborn tiny lights vs. 
clustering darkness forever ok?