This Fortnight on perl5-porters (23 October-5 November 2006)

This Fortnight on perl5-porters - 23 October-5 November 2006

   Yes, I complained to Corel, and they said "thank you for your insight
   as a valued customer, we forwarded this to our manager of customer
   support". So maybe someday they will fix the problem, or maybe they
   will not bother. -- Glenn Linderman, being realistic.

Topics of Interest

New version diagnostic breaks a bunch of modules

   The discussion of trapping error messages, and future-proofing the
   code that traps error messages continued on its merry way this week,
   with lots of attempts and trying to figure out what the code would
   look like from the client side. If that was sorted out, the
   implementation would be trivial. The biggest issue was minimising the
   amount of makework code required on the client side, otherwise people
   will never remember the incantation and will get it wrong and/or waste
   time.

   I would say Glenn Linderman made the best proposal, way down at the
   end of the thread, with his "errorcodes" module. But then I'm not sure
   I'm qualified to judge, since *my* code never has errors.

     http://xrl.us/s5fp

   And the thread trickled on into November.

     http://xrl.us/s5fq

Can't compile blead on SuSE 10.1 (x64_64)

   Andy Dougherty and Cosimo Streppone waded through the difficulty of
   getting Perl compiled on a 64-bit SuSE linux host. But by the end of
   the fortnight, Tels, who raised the original problem was still not
   getting complete satisfaction.

     http://xrl.us/s5fr

Patches for dual-lived modules

   Jerry D. Hedden wanted to know if patches could be forwarded to him
   first, instead of "blead", as it would result in fewer patches all
   round. There was some reluctance, since there are many cases where the
   putative maintainer is busy with Other Things in Real Life and are not
   always as responsive as Jerry. Thus, people like to be able to make
   changes to the codebase and worry about CPAN catching up afterwards.

   In terms of the "threads" module, Dave Mitchell stated that he still
   considered the core as being the primary "home" of the source, the
   CPAN modules just being a way for people to get new "thread" goodness
   now, without having to wait for 5.10.

     http://xrl.us/s5fs

Configure patch for "5.\d\d.\d+"

   Andy Dougherty thanks H.Merijn Brand for taking the time to prepare
   this patch. H.Merijn pointed out that it was unlikely to be exercised
   by the current test infrastructure, and if people cared about older
   perls they would have to pay special attention.

     Listen up
     http://xrl.us/s5ft

A call for "File::Spec"/"Cwd" maintainers

   Ken Williams announced that his copious spare time is no longer
   sufficient to devote the time required to keep these two modules happy
   and bug free, and asked for volunteers interested in becoming
   co-maintainers.

   Johan Vromans kicked off the idea of a small working group with access
   to a wide variety of platforms and perls to sit down and and figure
   out how to cross-platform file-system manipulations the Right Way. Ken
   Williams thought that "Path::Class" was the right way, but admitted to
   being slightly biased, since he wrote it.

     http://xrl.us/s5fu

Profiling and "dprofpp"

   Nicholas Clark bemoaned "dprofpp"'s sluggishness at processing a 150MB
   tmon.out file, and wondered whether anyone who had said that they
   would take a look at the problem had ever made any headway. He
   wondered if the suggestion to rewrite it in terms of Simon Cozens's
   "Devel::DProfPP" module was feasible. For starters, he wasn't sure of
   how to go about setting up regression tests.

     http://xrl.us/s5fv

"Data::Bind" compilation failure with blead

   This failure was caused by the fact that "warnings.pm" no longer loads
   "Carp" at compile time, only if needed, and this masked what was,
   strictly speaking, a syntax error in "Data::Bind".

   If the change that gave rise to this were to be backported to "maint",
   a number of CPAN modules would break, which would mean that 5.8.9
   would not be a drop-in replacement for the 5.8.x series. Yves wondered
   whether it was sufficient to flag it as an important "main" upgrade
   issue, and document a work-around.

     http://xrl.us/s5fw

Closures with named subs

   Christian Winter was puzzled by how closures behave when the
   closed-over routine is named, and the documentation didn't help him
   understand what was happening.

   After it was explained to him, he cooked up a patch for "perlref.pod",
   which Rafaël Garcia-Suarez applied.

     http://xrl.us/s5fx

Valgrind findings

   Rafaël ran "valgrind" over blead, and noted that the memory was
   leaking like a sieve. Nicholas made a couple of suggestions on leaks
   that may be caused by optrees being half-destructed. Yves cleaned up
   the leaks from the regular expression engine.

   Rafaël ran a second round, and 14 previous test files came up clean.

     http://xrl.us/s5fy

   He found two leaks with "warnings.pm". One, he fixed, the other, he
   did not know how to proceed.

     http://xrl.us/s5fz

Perl source code protection and the demise of "B::Bytecode"

   Nicholas Clark received out-of-band feedback on the announcement that
   "B::Bytecode" has been dropped for 5.10. Turns out there are people
   out there who are using it to deliver shrouded Perl code.

   Nicholas pointed out that it was dropped because no-one who cared
   sufficiently about the matter had neither the time nor inclination to
   look after it. If someone starts to maintain it again then it's
   another story. In the meantime, he wondered what other solutions were
   available to "protect" Perl source code.

   Steve Hay's "Filter::Crypto" probably comes the closest these days.
   Nicholas, imitating Bruce Schneier, noted that "As the attacker, you
   only have to find the weakest link. As the defender, you have to
   ensure that no leaks are weak. The defender can only delay the
   inevitable."

   Adam Kennedy thought that munging the code through "Perl::Squish" and
   then possibly creating random xyzzy variable names would go a long way
   to making the code sufficiently difficult to understand. You could
   also check that the test suite still succeeds after shrouding.

   Andy Dougherty mentioned that it might be worthwhile hanging out a
   sign in the usual places saying "Orphaned modules! The following
   modules will be removed from 5.10 unless someone offers to maintain
   them". Not that he expects anyone to reply, but at least that way we
   don't have to feel guilty about it.

   Scott Walters admitted to liking Logo and SNOBOL, and that it might be
   fun some day to revive the Bytecode material in order to allow those
   languages to emit Perl bytecodes, which could then run Perl (and
   access CPAN). Some day.

     http://xrl.us/s5f2

   Last words on the matter from Tels, in November:

     http://xrl.us/s5f3

UTF-8 Failures in smoke ($PERL_UNICODE)

   An old bug from several months ago raised its head again. With the
   restructuring of some part of the internals, we achieved the
   possibility of have two right answers to a test, and Nicholas Clark
   couldn't find an easy way to hack the test suite to cope with the fact
   that (to paraphrase) "foo()" could return "bar" or "rat", and either
   would be okay. He was then thoroughly swamped by hordes of volunteers
   beating a path to his Inbox offering to help out. (I am being
   sarcastic).

   The problem surfaced again, this time managing to snag Dave Mitchell's
   attention (who lamented that his p5p spool currently stands at over
   4000 messages), and so he missed it the first time around. (And what
   are my summaries? Chopped liver?)

   As the warnings code was mainly Dave's handiwork, he was able to craft
   a fix to improve the situation.

     http://xrl.us/s5f4

Unclear version error message

   Glenn Linderman was playing around with PAR, and didn't realise that
   WordPerfect Mail had discretely slipped a perl58.dll into
   c:\windows\system when he wasn't looking. So the PAR stuff spat out a
   strange message about a version of Perl he didn't have, and it took
   him a certain amount of time to figure out why things were
   misbehaving.

   To cut a long story short, it would have helped if canonical file
   names appeared somewhere in the error message. The fact that Glenn had
   been using PAR meant that $^X and $0 didn't point anywhere near the
   library.

   Yves pondered whether it would make more sense for Perl to use a
   little more of the Windows infrastructure, and stashing version
   information of installed modules into the registry. Andy Dougherty
   wasn't too sure about this, feeling that this was more of a vendor
   issue than one for the porters.

   Vadim Konovalov pointed out that the registry was not a good idea for
   a number of reasons. A big problem is that locked-down business
   installations may not even let the user account write to the registry.

   Glenn thought the whole registry business was annoying, because if you
   copy an application from an old machine to a new one, it doesn't work,
   because of all the missing registry entries. At this stage, the thread
   started to discuss the finer aspects of how to get multiple Perl
   installations playing nicely on the same machine, and strategies for
   deal with moving the Perl directory around and still have it work.

     http://xrl.us/s5f5

   Andy Dougherty provided a useful executive summary here:

     http://xrl.us/s5f6

INC handlers and __FILE__

     http://xrl.us/s5f7

A selfless implementation

   Chia-liang Kao asked what the porters thought of his module
   "selfless.pm", that does a "my $self = shift". The reactions varied
   from "cute" to "sick".

     http://xrl.us/s5f8

Patches of Interest

Deparse bug redux

   Stephen McCamant followed up on Juerd's incorrectly deparsed monster
   reference "{{{{{[[[[[[[[[[]]]]]]]]]]}}}}}" and produced a real program
   puts it in context and produces bad behaviour. He also bundled in a
   patch, to correct the problem in B/Deparse.pm.

     http://xrl.us/s5f9

A stab at "UNITCHECK" blocks

   Now available as a module on CPAN.

     http://xrl.us/s5ga

"FindBin.pm" fixed wrong treatment of PATH entries

   Alexey Tourbin had a problem with FindBin getting mixed up with
   executable files appearing in directories on DOS-ish platforms. In a
   nutshell, he wanted to skip any irrelevant files that may be
   encountered.

   Adam Kennedy suggested that Alexey's one-line fix would be complete
   with a test.

     http://xrl.us/s5gb

Fix a problem with jump-tries, add "(?FAIL)" pattern

   Yves Orton discovered a flaw in his previous work on adding jump tries
   ("/(foo[ab]|bar[cd])/" worked, but "/(foo[ab]|bar[cd])+/" did not). In
   the process of fixing it, he invented a new regop FAIL, which deals
   with things in a more elegant manner. And some tests, too.

   This lets you specify deep in the middle of a pattern that, no you
   really don't want to match anything at all. Sometimes, this comes in
   handy.

     http://xrl.us/s5gc

Supporting 'threads' with multiple embedded Perls

   Jerry D. Hedden landed a patch to allow multiple Perl interpreters and
   threads play nicely together, following an issue raised by Jan Dubois.

     the big issue
     http://xrl.us/s5gd

   Jan had a look at the code and made a couple of suggestions on how to
   improve it.

     http://xrl.us/s5ge

Add a few useful developers maketargets to win32/Makefile

   Yves Orton tweaked the Win32 Makefile to add a couple of targets,
   "regnodes", which comes in handy when hacking on the regular
   expression engine (one can see what itch this scratches) and "regen"
   which does the whole lot. Making only "regnotes" avoids a considerable
   amount of useless recompilations.

     http://xrl.us/s5gf

Add a commit verb to regex engine to allow fine tuning of backtracking 
control

   Joshua ben Jore appears to understand some of the more esoteric
   improvements that Yves has been making in the regular expression
   engine. He asked how "(?COMMIT)" behaves in terms of "(?>...)" and was
   most impressed with the answers Yves gave. Since I've never taken the
   time to understand the usefulness of "(?>...)" in the first place, it
   all went slightly over my head.

     http://xrl.us/s5gg

Removing the beta status from the "IO::Compress" modules

   Paul Marquess expressed the belief that the "IO::Compress" modules
   were sufficiently stable to be moved out of went out of beta status.
   He made one final tweak.

     http://xrl.us/s5gh

   This triggered some problems with threads and "Readonly", and so he
   fixed that up.

     http://xrl.us/s5gi

   And then bumped the version numbers and called it a day.

     http://xrl.us/s5gj

Add more backtracking control verbs to regex engine (?CUT), (?ERROR)

   More backtracking goodness escaped from our favourite mad scientist of
   the regular engine. I'll have to play around with all this stuff to
   see what sense I can make of it, but it certainly looks nifty.

     http://xrl.us/s5gk

Monitoring wedged tests on Win32

   Steve Hway was having problems with his smoke machine. Sometimes a
   test will hang, and the test run is ruined. It used to be worse, but
   it's still not perfect.

     http://xrl.us/s5gm

   So a method is needed to monitor the tests, and detect when they get
   wedged. And, more importantly, killing them when they *do* get wedged.
   Jerry D. Hedden offered a patch for t/TEST that sets up a monitor
   thread to keep an eye out for tests that get stuck (and thus
   completely ruin a smoker's evening).

   Unfortunately, it didn't work out as expected, since it appeared that
   when things go wrong and the monitor thread tries to kill the blocked
   thread, it is the parent of the blocked thread that winds up taking
   the bullet.

   Jan Dubois said that a robust solution to this would be to use
   "Win32::Job", a module that ActiveState wrote to help keep work with
   building ppm distributions, and not having one bad package in the
   batch blocking the show. But alas, "Win32::Job" is not in the core.

   Nicholas Clark did not see this as an obstacle. If the module was
   needed, in order to test core modules, then there was no reason it
   should not become core.

   Another thing Jan wanted to do was to emulate Unix's "kill -9, $pid",
   to take out a whole process group in one fell swoop. He was strongly
   encouraged to proceed with this.

     http://xrl.us/s5gn

New and old bugs from RT

Special var "@-" becomes arbitrarily large (#36046)

   Yves Orton figured that this was fixed in "blead", and added a couple
   of tests to make sure it stays that way.

     http://xrl.us/s5go

Use of "study()" with utf8 enabled breaks regexps (#37646)

   Similarly, Rafaël Garcia-Suarez noted that this bug was also fixed in
   "blead".

     http://xrl.us/s5gp

   "sprintf "%#04X"" also uppercases the 0x-prefix (#40583)

   Dr. Ruud noticed that, for instance, "sprintf "%#04x", 15" produces
   the slightly odd looking "0X0F", and contended that it should produce
   0x0F, as per the C spec, or the Perl documentation, or something.

   This kicked off a large thread where it was noted that Perl lets
   "sprintf" produce binary "0b001011" strings, but not "0B001011", that
   perl doesn't know how to "eval "0X0F"" and a few other things besides.
   By the end of the thread, "blead" had been patched in various
   different ways, tests added and documentation amended, in an attempt
   clean up most of the glaring inconsistencies.

     http://xrl.us/s5gq

   Source code patch for win32/perlhost.h (#40591)

   Kenneth L. noted a problem with building perl on Win32 with "dmake"
   and "MinGW". Steve Hay noted that it was fixed in "blead", and
   suggested what packages Ken should download in order to build a perl
   without such problems.

     http://xrl.us/s5gr

Out of memory message should not require memory allocation (#40595)

   Schmorp (possibly Marc Lehmann in disguise) found that when perl runs
   out of memory, it needs to allocate memory in order to print the error
   message. But it runs out of memory, so it has to allocate some memory
   to... you get the picture. And Schmorp gets a segfault.

     there must be A Better Way To Do It
     http://xrl.us/s5gs

"gnu/linux" (glibc) likely needs "USE_PERL_SBRK" (#40603)

   Marc Lehmann found that bad things happen when one uses modules that
   use pthreads with a perl built to use its internal "malloc" (via
   "usemymalloc=y"). It seems that both "glibc" and perl's "malloc"s wind
   up allocating overlapping areas, with predictably hilarious results.

   It turns out that both perl and glibc call "sbrk" to acquire more
   memory, but "sbrk" is not thread-safe, so concurrent calls all get the
   same result.

   Andy Dougherty wondered whether the hints for linux/glibc should
   prevent "usemymalloc=y" from being chosen, or whether "usemymalloc=y"
   provides such benefits that it may be worth spending some effort to
   get everything playing nicely.

   Nicholas Clark remembered that people have been having trouble with
   threads on FreeBSD, and that it may well be for this very same reason,
   and "usemymalloc=y" is definitely worthwhile on that platform.

     http://xrl.us/s5gt

"srand()" behaviour with large numbers (#40605)

   Brian Szymanski uncovered some nasty behaviour with "srand()" when the
   seed approaches the size of the CPU width.

     http://xrl.us/s5gu

Crash with unicode characters in regex comment (#40641)

   Where yet again Sadahiro Tomoyuki does battle with UTF-8...

     and wins!
     http://xrl.us/s5gv

(Obscure) Bug in Dynaloader (#40651)

   Why you should always assign to $VERSION in a "BEGIN" block.

     http://xrl.us/s5gw

Unclear version error message (#40652)

   The bug report of the problem raised by Glenn Linderman (see Topics of
   interest).

     http://xrl.us/s5gx

Bleadperl crash in "Perl_pp_entersub()" (#40681)

   Interesting thread, not enough time to summarise it, sorry.

     http://xrl.us/s5gy

Perl5 Bug Summary

     8 more, 5 fewer, leaves 1531
     http://xrl.us/s5gz

     http://rt.perl.org/rt3/NoAuth/perl5/Overview.html

New Core Modules

   *   "Object::Accessor" was added to the core.

         http://xrl.us/s5g2

   *   After a debate over the accuracy of the name, "Term::UI" was added
       to the core.

         too late to rename it
         http://xrl.us/s5g3

   *   "threads" underwent version inflation last fortnight

         1.45
         http://xrl.us/s5g4

         1.46
         http://xrl.us/s5g5

         1.47
         http://xrl.us/s5g6

         1.48
         http://xrl.us/s5g7

         1.49
         http://xrl.us/s5g8

   *   And "threads-shared" wasn't left behind, now up at version 1.05

         http://xrl.us/s5g9

   *   And Michael G. Schwern announced the release of a beta version
       (0.64_03) of testing goodness.

         Test::More/Simple/Builder
         http://xrl.us/s5ha

In Brief

   Andrew Savige wrote a new test for close-on-exec ($^F) in
   t/run/cloexec.t, as there were no tests for it. Since the test used a
   magic number, Steve Peters thought that it should be hidden behind a
   preprocessor macro in "perl.h".

     This test brought to you by the number 3 and the letter F
     http://xrl.us/s5hb

   The problems surrounding change #29050, a memory leak fix by Jarkko
   were all sorted out. There was still a problem with "glob" and
   "threads" on VMS that Craig A. Berry needed to look at.

     done and dusted
     http://xrl.us/s5hc

   Craig reported that this was due to asymmetry in reference counting in
   "PerlIO_tmpfile".

     http://xrl.us/s5hd

   Vadim Konovalov wanted to know why DynaLoader's dl_win32.xs was
   located in ./win32 and not ./ext/DynaLoader along with everything
   else.

     http://xrl.us/s5he

   David Feldman began work on a patch to provide better
   "Attribute::Handlers" diagnostics.

     http://xrl.us/s5hf

   Alexey Tourbin noted that the documentation and behaviour of
   "sv_setref_pv()" differ, and couldn't decide if this was a bug or a
   feature.

     http://xrl.us/s5hg

   Andreas König still didn't know what do about change #24542 breaking
   "Math::Pari".

     http://xrl.us/s5hh

   Rafaël crossed off another perltodo TODO: "readpipe" and "qx()"
   (backticks) are now overridable. Saves having to pull in an IPC
   module.

     http://xrl.us/s5hi

   Considerable progress was made on getting perl built with VC++ 2005
   (VC8).

     http://xrl.us/s5hj

   Andreas König noted that "XML::Writer" 0.601 throws the new Variable
   length character upgraded in print diagnostic, which means it probably
   needs to be tweaked.

     ooh, we found a bug
     http://xrl.us/s5hk

About this summary

   This summary was written by David Landgren.

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-- 
"It's overkill of course, but you can never have too much overkill."