Nicholas: So, it seems that constant folding runs in ``compile time'', which scares me somewhat. Surely it should be running in run time?
Rafael: The whole point of compile time optimisation is that it runs at compile time, isn't it?
Nicholas: Runs at compile time, but (I assume should) run under run time rules. There appear to be special exceptions scattered throughout the code that certain things aren't fatal if compilation is in progress.
(debating the elegant simplicity of the Perl 5 internals).
pp_const cools off Nicholas Clark applied Vincent Pit's patch from last week to slim
down pp_const by splitting the op into two, which eliminates a
costly branch.
Sébastien Aperghis-Tramoni reported that his web service that showed the gcov output of the Perl codebase had gone belly up (it was by poring over a gcov run that Nicholas spotted the original opportunity to optimise).
Abe Timmerman said that a similar offering of his own was still up, except that the perl.gcov target was currently broken, so there was nothing to show.
paths not taken http://xrl.us/bgwud
Jim Cromie and Reini Urban discussed the finer points of testing the B
modules.
http://xrl.us/bgwuf
Reini posted some B::Debug enhancements.
http://xrl.us/bgwuh
Reini finished up with the delivery the delightfully named B::MAD
module. He wasn't sure of the usefulness, but reasoned that some mad
hacker might be able to put it to use.
don't worry B::Happy http://xrl.us/bgwuj
Jim Cromie found a simpler way to set up the environment of a test
requiring a fresh perl to be launched. This was to allow PERL_XMLDUMP
to be specified, in order to verify MAD output.
Nicholas wondered if Jim's hack was VMS-compatible. Craig A. Berry
suggested that all that was needed was the correct use of local.
Hilarity ensued as Yitzchak Scott-Thoennes shot down each of Jim's
attempts to effect the change in a loop, which had the result of
the localness (locality?) evaporating at the end of the block.
need a hash slice to go http://xrl.us/bgwum
Somewhere along the way, Jim noticed a couple of warnings about unused variables when MAD is enabled.
http://xrl.us/bgwuo
Nicholas Clark continued with his interesting self-contained
task from last week that dealt with constant optimisations and
thought it should be possible to unroll constant packs.
(like $var = pack("a2", "xyz") being replaced by $var = "xy").
He had the source code that could more or less do it, but ran
all around the codebase trying to find a place to lodge it so
that it would be acted upon at the right time. He finally wound
up where he started from, and realised that it wasn't possible.
nor do you always get what you need http://xrl.us/bgwuq
Nicholas Clark and Andy Armstrong came through with the goods to
figure out what was going wrong with IPC::Shareable and
IPC::ShareLite on the upcoming Fedora release. So Fedorans will
soon be able use 5.10 straight out of the box.
http://xrl.us/bgwuu
Ken Williams considered the recent change to the documentation concerning the modulo operator and suggested some further tweaks that Rafael applied.
He then started thinking about moduli of floating point numbers and was surprised by the results of the current implementation. Zefram pointed out that the same issue is described in his bug #41215.
Ken would have liked to make things behave in a more logical manner, but Rafael was happy to let sleeping dogs lie.
http://xrl.us/bgwuw
Gowtham wanted to know if the perl port that ran on Symbian 8 was usable on Symbian 9. Jarkko Hietaniemi, author of the the original port, was sceptical, given that the platform had been locked down. This might mean that Perl (as an ``unauthorised application'') would not have the privilege of opening a TCP connection.
If the build toolchain has changed significantly then major work will be required to bring the port up to speed. In any event, Jarkko said that he had no more time to take care of it.
sounds like no http://xrl.us/bgwuy http://xrl.us/bgwu2
PERL_RUNTIME, or, adventures in sprintf ops Having discovered the nifty f flag and its positive impact on length,
Nicholas reasoned that sprintf was a likely candidate for more of
the same. Except things went wrong, and had him diving all the way
back to Malcolm Beattie's change #44 from 1997. He managed to sort
things out and wrapped it up in change #33369.
http://xrl.us/bgwu4
use encoding 'utf8' bug for Latin-1 range Jarkko Hietaniemi kicked off a long thread last week, and was
still bubbling along nicely as I summarised it. So the executive
summary (subject to change, next week) is that use encoding
is broken and its use should be discouraged.
http://xrl.us/bgwu6
More UTF fun this week. Phil Harvey wrote to explain how he had
been burnt by the changes to U0 and C0 flags for unpack,
that used to allow one to sneak past the abstraction model and
poke at the implementation details. This caused a number of
mutually irreconcilable problems, and so the decision was made
during 5.9 to make a clean break with the past.
it /was/ noted as an Incompatible Change http://xrl.us/bgwu8
Tels discovered ohloh, and its spectacularly out-of-date idea of activity on the Perl codebase. It was slurping the contents of Sam Vilain's git repository, and choking on the complex history of the codebase. This meant that it looked as if development stopped years ago. Andy Armstrong fixed up the summary info to indicate that Perl 5 is still alive and kicking.
http://xrl.us/bgwva
Michael G. Schwern questioned the desire to exclude threads modules from being installed on non-threaded builds. His contention being that if someone uses the module on a non-threaded build, they get a nice, informative error message as to why things don't work.
If they are removed, then only a basic ``module not found in any of these zillion directories'' message is issued instead. Michael was worried that some people might go to all the effort of trying to download the threads package from CPAN, only to find out that it still doesn't work, and in fact cannot unless perl itself is rebuilt.
Jerry D. Hedden saw the logic in this line of reasoning, and reversed his stance.
helpful errors http://xrl.us/bgwvc
back they go http://xrl.us/bgwve
Elsewhere on planet threads, Jerry pushed some more updates out.
threads 1.69 http://xrl.us/bgwvg
threads::shared 1.17 http://xrl.us/bgwvi
Thread::Semaphore 2.07 http://xrl.us/bgwvk
Thread::Queue 2.06 http://xrl.us/bgwvn
perl -M:Foo -we 1 Robin Barker related a london.pm discussion (and curiously,
the discussion was about Perl) relating to perl -M:DProf -we 1 not
generating a warning. So he tweaked the getopty code in perl.c
to make it do so. Jim Cromie thought that the proposed warning, so
worded, was not particularly helpful.
-M doesn't get the colon http://xrl.us/bgwvp
http://london.pm.org/pipermail/london.pm/Week-of-Mon-20080218/012723.html
Brendan O'Dea converted Changes to UTF-8. I don't know what happened in transit, but the result was a mess by the time the message hit my inbox.
http://xrl.us/bgwvr
Reini Urban proposed a change to the various lib paths. Rafael admitted the current mechanism was a bit ad-hoc and it reminded him that he needed to work on a 5.12 roadmap.
Andy Dougherty explained how things are supposed to behave currently.
http://xrl.us/bgwvt
Nicholas Clark tried to apply Marcel Grünauer's fix to NEXT
but patch failed miserably in the attempt. Nicholas blamed
Apple's software.
http://xrl.us/bgwvv
Jerry D. Hedden discovered that his thread segfaults would occur regularly on a machine with 4Gb of RAM, but not on another that had only 1Gb. He wondered if it could be the symptom of some bad signed/unsigned voodoo.
Tels replied that he was unable to provoke any crashes on his own machine.
http://xrl.us/bgwvx
Matt Kraai diagnosed a series of test failures he was having on QNX. Two
could be traced to tests building a .pbc file and then trying to
overwrite it after it had been loaded. His brutal fix for that problem
was to delete the file before overwriting it, but suspected there was
a better approach to the problem.
The second series of tests were due to bugs in QNX's atof. So the
fix here would be to tweak Configure to use Perl's own implementation.
http://xrl.us/bgwvz
Yves Orton stopped and suggested a couple of source code changes to try and regretted that he didn't have more time to devote to the issue. He nevertheless found the time to commit change #33324 that he hoped would resolve the problem.
Apparently, it did.
In other news, Michael Schroeder (reporter of the bug) asked why
$r=qr{^bar}; "foo\nbar" =~ /$r/m or die dies on blead, but not
on 5.8. He tracked down where in the regexp engine things had
changed (no mean feat) and wondered what the reasoning was.
Rick Delaney explained that he had made the change to fix a related matching problem, and had not thought to add a regression test that would have caught the change that Michael tripped over.
Yves felt that it could be fixed for 5.10.1.
http://xrl.us/bgwv3
Daniel Quinlan supplied a patch to the Darwin hints file to allow a 64-bit perl build. Rafael applied the patch but Nicholas warned that there may be problems, since the 64-bitness of the build would not be reflected in machine/architecture pathnames. This could lead to all sort of mixed-bitness nightmares if different builds coexisted on the machine. Unless of course Darwin just does the right thing.
http://xrl.us/bgwv5
pod2man needs to translate some ASCII characters (#50950) Mike Ward complained that backticks and dashes were being incorrectly
translated by Pod::Man.
http://xrl.us/bgwv7
Elad Dotan reported having trouble building Perl on Solaris, but provided so little information that diagnosis was difficult. Andy Dougherty tried, though.
http://xrl.us/bgwv9
defined(\&sub) (#51072) Dagfinn Ilmari Mannsåker discovered that trying to call
->next::can on a package that has not (yet) been defined
will cause a segfault. Rafael wrote a nifty patch to autovivify
it as an empty package.
http://xrl.us/bgwwb
288 new + 1499 open = 1787 (6 more, 4 less) http://xrl.us/bgwwd
http://rt.perl.org/rt3/NoAuth/perl5/Overview.html
Andreas König was surprised to discover that Devel::LeakTrace
was broken, and in fact had been so since change #17968 from 2002.
He wasn't sure on which side the fault lay.
http://xrl.us/bgwwf
Robin Barker discovered some C files in the test suite that needed some consting goodness applied.
http://xrl.us/bgwwh
The recent change #33291 had VMS falling off the wall, so John E. Malmberg and Craig A. Berry put it back together again.
the king's men http://xrl.us/bgwwj
Reini Urban gave the Cygwin hints a little TLC. Applied.
http://xrl.us/bgwwm
Steve Hay revived the discussion about automated generation on Win32 configuration information, saying that he had improved the situation with some Makefile trickery, but full automation remained elusive.
bespoke configuration http://xrl.us/bgwwo
Porting/expand-macros.pl really does indenting now. (Change #33352).
http://xrl.us/bgwwq
Jim Cromie tweaked his recent opcode generator tweaks, shaving a few more bytes from op.c.
http://xrl.us/bgwws
This summary was written by David Landgren.
Last week's is here
This Week on perl5-porters - 10-16 February 2008 http://xrl.us/bgwwu
Weekly summaries are published on http://use.perl.org/ and posted on a mailing list, (subscription: perl5-summary-subscribe@perl.org ). The archive is at http://dev.perl.org/perl5/list-summaries/ . Corrections and comments are welcome.
If you found this summary useful, please consider contributing to the Perl Foundation to help support the development of Perl.