"So we're doing things at BEGIN time in UNIVERSAL with source filters. With a garnish of messing with @ISA in some other classes. What could possibly go wrong?" -- Nicholas Clark, trying to address serious bugs lurking somewhere in code this funky.
More feedback on the march to 5.8.9. Dave Mitchell fixed up the
problems with SUPER method caching. Nicholas uncovered a can of
worms in Attribute::Persistent.
Indeed, imacat had found the problem six months ago.
File::Path was the long pole holding up the tent for
the past couple of weeks (my fault). 2.07 is now on CPAN, and
addresses the symlink flaw that the Debian project uncovered.
slogging on http://xrl.us/ow3g3
Tony Cook fixed up a C configure probe that wasn't valid under C++. H.Merijn Brand thanked him and stowed the change away in the metaconfig machinery.
better C park http://xrl.us/ow3g5
@{"_<$filename"} is unreasonably tied to use of DB::DB ($^P & 0x2) Tim Bunce learnt that you can't introspect the source code of files
without dropping down into single-step mode. This made him sad, because
it meant that evaled code was more or less out of reach of his
current obsession, Devel::NYTProf.
Not letting such a minor issue get in his way, Tim proposed a patch to give him sufficient fine-grained control to achieve his ends. Nicholas Clark found the time to run with the patch and produce something that was compatible with 5.8.9-RC1 (yes, coming soon to a mirror near you).
profiling evals http://xrl.us/ow3g7 http://xrl.us/ow3g9
On the continuing saga of Karl Williamson's single-handed battle to slay
the Unicode deficiencies in Perl, Juerd Waalboer commented that use ascii
had a lot going for it as a putative pragma to deal with the matter. Rafaël
wanted to see 'legacy' appear somewhere in the name.
Tom Christiansen penned a fine missive on the perils of \w, \s, \b
and even \d, pointing out that a certain dingbat character is classified
as a digit, but alas, MATHEMATICAL SANS-SERIF BOLD ITALIC CAPITAL PI
isn't. Which is he's given up on all those shortcuts. As a parting gift,
he offered some code to check ASCII characters against all Unicode
properties and so forth.
Yves Orton had a look at the matter from the perspective of the regular
expression engine, and felt that adding /a and /u modifiers to
enforce ASCII or Unicode semantics would be horribly painful to implement,
and said that he was leaning more towards ASCIIish semantics (for instance
\d, \w and \s would recover their pre-Unicode meanings), the idea
being that people doing Unicode can use properties instead.
this property is condemned http://xrl.us/ow3hb
perl5db questions Edward Peschko had some questions about how the Perl debugger
interacts with the perl binary, so that he could debug the debugger
debugging a Perl script with gdb. Nicholas Clark pointed him in
vaguely the right direction. Richard Foley suggested quite innocently
to Edward that if he came up with anything useful it would be
worthwhile patching the debugger or Devel::Trace.
a debugger's debugger http://xrl.us/ow3hd
Michael G. Schwern wondered with the documentation for file test
operators (-f, -s ...) lives in perlfunc rather than
perlop. Eirik Berg Hanssen pointed out that if such a change
was made, then he would miss the perldoc -f -X shortcut.
David Nicol pointed out that perlfunc also mentions last,
next and redo, which are flow control syntax. And thus it's
easy to get at them with perldoc -f too.
Renée Bäcker had a patch lying around in an RT ticket
(bug #27886) that, if applied, would extend the -f switch
to look inside perlop as well.
In the end, the problem is no so much where the documentation lies, but rather one of how easy it is to obtain.
http://xrl.us/ow3hf http://xrl.us/ow3hh
qv() confusion Following on from the humonguous threads about version comparison code (and the injection of things into the UNIVERSAL namespace), John Peacock put forward a proposal to try and put an end to the confusion that surrounds the issue of handling version numbers in Perl.
Michael G. Schwern penned a very thoughtful reply describing the problems in terms the mental representations that people have developed to remember how (they think, correctly or otherwise) version numbers work. He continued by reviewing the documentation, suggesting better examples, and pointing out that the fact that 1.2 is considered greater than 1.3.0 is a trap waiting to fool the unwary.
Dave Golden also chipped in with a number of sensible suggestions and volunteered to rewrite the documentation in terms of whatever changes were finally agreed upon.
http://xrl.us/ow3hj http://xrl.us/ow3hm
Nicholas Clark uncovered a problem with the version of the CPAN
shell slated to be included in 5.8.9. Since the p5p summariser was
busy with other matters In Real Life and had not wrapped up the
final version of File::Path, Nicholas had the time to confer
with Andreas König to determine the right thing to do.
http://xrl.us/ow3ho http://xrl.us/ow3hq
Time::Local? Dave Rolsky was so impressed by Time::y2038 that he planned to rewrite Time::Local in terms of it, and add a warning saying it was deprecated and just use Time::y2038 instead kthx.
Jesse Vincent wanted to know if Dave meant a warning in the documentation, rather than the code, since there must be an awful lot of code in the DarkPAN that uses it. Dave did indeed mean a disclaimer in the documentation.
He had a second look, and decided that it wasn't even worth the hassle of trying to do anything, other than just recommending people use Time::y2038 and be done with it.
http://xrl.us/ow3hs
A task that needs some Perl and internals knowledge.
Code such as this
use constant PI => 4; warn PI;
will currently deparse as
use constant ('PI', 4);
warn 4;
because the tokenizer inlines the value of the constant subroutine PI.
This allows various compile time optimisations, such as constant folding
and dead code elimination. Where these haven't happened (such as the example
above) it ought be possible to make B::Deparse work out the name of the
original constant, because just enough information survives in the symbol
table to do this. Specifically, the same scalar is used for the constant in
the optree as is used for the constant subroutine, so by iterating over all
symbol tables and generating a mapping of SV address to constant name, it
would be possible to provide B::Deparse with this functionality.
checkpods -> podchecker Woohoo! Alex Vandiver took a crack at solving the checkpods/podchecker
redundancies, and supplied patches galore to do the deed.
TODO: patch review http://xrl.us/ow3hu
Robin Barker sent in a patch to fix up an error that occurs when
the PREFIX environment variable is set. Michael G. Schwern thanked
him for his work, and tossed in a couple more suspect variables names
into the mix.
http://xrl.us/ow3hy
Robin also made a couple of changes in op.c to change while(cond);
constructs to while(cond) {}. He thought this made the empty loops more
explicit, and besides, it silences a g++ warning. Rafaël Garcia-Suarez
applied the patch in the following month.
meanwhile http://xrl.us/ow3h2 http://xrl.us/ow3h4
Tom Christiansen went through all the C source files and corrected
the Tolkien quotes that appear at the top, and explained why it
was so important. Johan Vromans wondered why Tom had cited page
numbers, since these may change from edition to edition. Tom
thought that a good place to note the editions used would be in
perlhack, since only hackers would be likely to encounter
them in the source. This was accepted.
Jan Dubois gathered all the Tolkien quotes Sarathy used to announce the 5.005 builds.
Tom went back and produced a second patch, this time against blead. He noted that ext/threads/shared/shared.xs contains a non-Tolkien quote, and wondered if a better Tolkien quote might not be found, should the original authors of the file agree. Artur responded positively to the idea.
Working further afield, Tom found another quote that could be applied to ext/Win32CORE/Win32CORE.c.
The Road goes ever on and on http://xrl.us/ow3h6 http://xrl.us/ow3h8
@ARGV Moritz Lenz wrote a documentation patch to explain that <> doesn't
open files from @ARGV, but passes them to open() instead. After
careful review, it was applied.
http://xrl.us/ow3ia
Cwd::realpath doesn't work on files on Windows (#29570) Andrew Pimlott could no longer recall how to trigger this bug and suggested it could be closed.
reply to reopen http://xrl.us/ow3ic
Warren Dodge was pleased to hear that Michael J. Krueger was experiencing the same problems with a module from Rational that was failing on 5.10. He lodged a bug report (a PMR) with Rational and wanted to know if Michael gave him permission to forward his report to Rational as well. No word back from Michael.
http://xrl.us/ow3ie
$var, $arg, $type and $ntype XS variables (#51992) In response to Michael G. Schwern's plea for better documentation
on matters XS, Renée Bäcker replied with a web page that
he found useful. Living as it does in a ~person home page, it
would be good to get it onto the Wiki. (Hint hint).
but ask for permission http://xrl.us/ow3ig http://www.perlfoundation.org/perl5/index.cgi
It has to said: people make Perl do the strangest things. Consider the following program:
my $r = f();
my @a = @$r;
sub f {
push @a, undef;
return \@a;
}
It works, after a fashion, but the interpreter is left dithering as to whether it should panic or not. Six months later, Dave Mitchell gave his analysis on the underlying cause.
half way fixed http://xrl.us/ow3ii
m/a{1,0}/ compiles but doesn't match a literal string (#56526) Is now an error in blead.
and we test! http://xrl.us/ow3ik
v[0-9]+ as label (vstring) (#56880) Renée Bäcker sent in a patch to correct this problem, but Rafaël didn't like the patch format, and also asked about a boundary condition (labels with colons). Renée replied with a better patch, but wondered if the patch responded to Rafaël's initial criticism.
like a version, patched for the very first time http://xrl.us/ow3in
chr(0400) =~ /\400/ fails for >= 400 (#59342) Yves Orton dropped by to say that he thought it was fundamentally
impossible to reconcile octal escapes and backreferences within a
regular expression, and that by perl 5.14, octal escapes in a regular
expression should be illegal. For instance, the interpretation of
\17 is either the seventeenth back-reference or chr(15),
depending on spooky action at a distance.
Karl Williamson reiterated his request for a verdict on whether his patch is worthy or not (the main sticking point being whether it should be silent, a warning or an error, contingent as it is on machines having other than 8-bit bytes). Glenn Linderman replied, but said that the final cut belonged to the pumpking.
perl on a UNIVAC 2200 series? http://xrl.us/ow3ip
Karl Williamson noted that some characters are matched by both a POSIX character class... and the complement of the same character class. Ideally, all characters should be matched by only one or the other, not both.
Yves Orton ran some code to probe the Unicode space, and discovered a distressingly high number of Unicode characters with the same behaviour. He explained that the problem is essentially due to a speed optimisation, and the difficulty is reconciling not slowing down non-Unicode matches against a complete rewrite of the character class implementation.
Yves also noted that, to a certain extent, some of the problems
are of our own making, such as a discrepancy between what POSIX
defines, and what is implemented in mktables. Rafaël deflected
some of Yves's criticism by pointing out that perltodo already
stated the how the current situation was broken. Yves continued
with a post mortem of decisions past, pointing out where and when
we messed up when bringing Unicode handling into Perl.
In another sub-thread, it took considerable traffic to define
the exact POSIX equivalency of \w.
the "you can have your pie and eat it" bug http://xrl.us/ow3ir
Nigel Sandever noted that unpack 'v/a*', qq[a] spat out a
'/' must follow a numeric type in unpack which was less than
helpful for understanding what the problem was. Marcus
Holland-Moritz agreed that the message stank and wrote a patch
to make things a little clearer. Rafaël was not entirely
convinced.
http://xrl.us/ow3it
Abigail discovered that -s -f 'zero-sized-file' works, but
-f -s 'zero-sized-file' doesn't. Rafaël fixed it.
http://xrl.us/ow3iv
mro::method_changed_in(..) ignores AUTOLOAD (#60220) Laurent Dami discovered that dynamically created AUTOLOAD
routines in parent packages aren't seen by previously dynamically
created child packages. Tony Cook offered a patch to correct this
situation.
I told you AUTOLOAD was evil http://xrl.us/ow3ix http://xrl.us/ow3iz
$#array in local sub array affects global $#array (#60222)
probably ENOTABUG http://xrl.us/ow3i3
Storable::thaw (#60232) Storable will require a module when asked to thaw an object.
Having a coderef in @INC to catch requirements of dynamically
created classes used to work in 5.8, but Laurent Dami discovered
that it is broken in 5.10. He provided a snippet to demonstrate
the problem, but no-one had a solution.
http://xrl.us/ow3i5
Crypt::Rijndael::decrypt (#60246) "vvv" reported a problem with Crypt::Rijndael. Nicholas traced the
problem down to two sources. The first one was with Crypt::Rijndael
not correctly terminating C strings with a binary \0. The second
was with the regular expression engine incorrectly relying on C string
behaviour and looking for a zero-terminated string, instead of using
the internal length attribute of the string. He suspected that it might
be possible to generate an incorrect result against a Perl string
containing an embedded binary zero.
we need a test http://xrl.us/ow3i7
croak(0) crashes (#60262) Marc Lehmann uncovered a flaw with croak but elicited no comments.
http://xrl.us/ow3i9
threads::shared resets %hash iterators (#60294) kbrintn showed a problem with hashes in threads, and how it becomes impossible to iterate over the keys within a hash of hashes.
http://xrl.us/ow3jb
1341 (+11 -9) http://xrl.us/owaqw http://rt.perl.org/rt3/NoAuth/perl5/Overview.html
http://xrl.us/ow3jd
Dave Rolsky uploaded a new version of Time::Local for the 5.10.1
and 5.8.9 maintenance branches, grumbling over the fact that core
was patched instead of having the changes dealt with first in the CPAN
version. This is an interim release until Dave and porters figure out
how to deal with the module in the light of Michael G. Schwern's
Y2038+ work.
http://xrl.us/ow3jf
This followed on from a thread started by Jan Dubois, who was anxious
to see Time::Local working on 64-bit platforms post-2038.
http://xrl.us/ow3jh
Andreas König ran into a warning with installperl and offered
a patch that Nicholas applied.
http://xrl.us/ow3jj
Karl Williamson wrote some code and asked the porters to please check if this small code snippet looks correct. But no-one did! I mean really, is it so difficult to confirm the right way to create a scalar value containing a single arbitrary unicode codepoint in UTF-8?
yes, apparently http://xrl.us/ow3jm
Renée Bäcker found another 7 tickets with patches in RT.
some assembly required http://xrl.us/ow3jo
Peter Scott wanted to have a warning on abandoned statements, thus
independently reinventing bug #59802 (return 0 or die). Elliot
Shank said that the problem was already solved with a Perl::Critic
policy.
http://xrl.us/ow3jq
Steve Hay has a Cygwin installation that is still unhappy with
the update to Archive::Extract 0.28.
http://xrl.us/ow3ju
Kevin Ryde spotted a flaw in the $Carp::Internal{__PACKAGE__}
documentation example (filed as bug #60300). Rafaël Garcia-Suarez
amended the documentation accordingly.
deceptive packaging http://xrl.us/ow3jw
Rafaël Garcia-Suarez applied Renée Bäcker's patch to solve the Too late for "-CS" option problem, thus closing bug #59652.
applied http://xrl.us/ow3jy
This Fortnight on perl5-porters - 28 September-12 October 2008 http://xrl.us/ow3j2
This Week on perl5-porters - 13-19 October 2008 http://xrl.us/ow3j4
This summary was written by David Landgren.
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 or attending a YAPC to help support the development of Perl.