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.
Weekly summaries are published on http://use.perl.org/ and posted on a
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