=head1 This Week on perl5-porters - 15-21 September 2008

I<This is sort of like one of those useless Windows alert boxes
that pop up to tell you something perfectly normal has happened and
you should do nothing. "A USB device was safely removed!" Yes, thank
you, I just removed it. It's this sort of hand-wringing user interface
design ("but the user might not have expected that USB device to
be removed, they should be told so they can maybe, possibly do
something!") that I'd like Perl to avoid.> -- Michael G. Schwern,
wanting numeric upgrades to JFDI.

=head1 Topics of Interest

=head2 Y2038 branch

Michael G. Schwern's work (in a git branch) on Y2038+ dates continued
apace, with H.Merijn Brand adding some configuration hooks for
minimum and maximum date values, and discussions of how to set up
tests to check for sane values in the year 803619167319 or so,
especially if daylight savings is still in place.

  fresh dates
  http://xrl.us/oscvv

=head2 Blead on OpenSUSE 11.0/64

H.Merijn Brand reported that the only failure on this platform for
5.8.9-to-be was one test in C<CGI>. On the other hand, C<ODBM_File>
was collapsing in a heap on blead, but H.Merijn was puzzled as to
why, since he was using the same configuration settings, and there
has been no changes under F<ext/ODBM_File> between 5.8.x and blead.

Andy Dougherty thought that 5.8.x's C<Configure> was missing
ODBM_File altogether, but blead's was a little more aggressive and
found a header that led it to conclude it could try and build
the extension, and this revealed that SUSE's dbm compatibility is
not up to par.

  not ODBC
  http://xrl.us/oscvx

=head2 C<autodie> behaviour with C<flock()>

Paul Fenwick asked what C<autodie> should do in the light of blocking
and non-blocking file lock acquisitions, reasoning that calling
flock() in blocking mode means "I need this lock", whereas calling
it in non-blocking mode is a question: "Can I get this lock right
now?". From this, he could come up with sensible behaviour for
C<autodie>.

The main sticking point was the possibility that a C<flock> call
returns the C<EWOULDBLOCK> error, which is not really an error, or
at least, not something worth dying for.

There was a long discussion about exceptions, errors and opportunistic
code, but the main point to take home is when Zefram pointed out
that if autodie's behaviour for flock is unsuitable, one is always
free to use a C<no autodie 'flock'> to switch it off and handle it
manually.

  blocked on flock
  http://xrl.us/oscvz

One may assume that Paul had been pulling his hair out over the
issue and that the documentation wasn't much help. So he improved
documentation for C<flock()> in F<perlfunc.pod> and tidied up the
code examples for by using lexical filehandles rather than globs,
checking for errors, and using constants rather than magic numbers.

  aiding the cargo cult
  http://xrl.us/oscv3

=head2 Is the prototype for C<CORE::truncate> wrong?

Paul then looked at C<truncate> in trying to figure out how to
override it for C<autodie>.  His version could not take a typeglob
as a parameter, as the parser thought it was a bareword, due to
C<truncate>'s prototype.

He missed the fact that C<truncate> can also work with the name of
a file, not just a file handle, which is why the prototype had to
fudge matters slightly.

This reminded Jan Dubois of a subtlety he encountered with C<unlink>
a while ago: C<unlink()> will remove the file named by C<$_>, but
C<unlink(())> does nothing. The reason for this oddity is to prevent
C<unlink(@stuff)> from unlinking whatever C<$_> points to, should
C<@stuff> happen to be empty.

Jan gave up trying to implement the same semantics in pure Perl,
instead concluding that there are some core functions that are
impossible to duplicate. And perl 5.10's C<_> prototype doesn't
help either, given that it imposes scalar context.

Rafaël wondered what would happen (what would break) if he tweaked
F<opcode.pl> to change the prototype to something more suitable for
Paul's need. Paul wondered too.

  trunk call
  http://xrl.us/oscv5

=head2 Practical considerations in changing the integer upgrade path?

Michael G. Schwern asked for people's considered opinions on how painful
it would really be to change the integer upgrade path from signed -E<gt>
unsigned -E<gt> double -E<gt> C<Inf> to signed -E<gt> long long (or
whatever) -E<gt> arbitrary precision.

Specifically, he wondered how one creates a new SV type, what impact
would this have on the code base, and whether it would break XS code.

Yuval Kogman answered all three questions quite clearly. And there
ended the thread.

  and python does it right
  http://xrl.us/oscv7

=head2 Change 30638 introduces regression

Following on from a change for bug #59168 reported by Father
Chrysostomos and an error in the test suite for C<XML::LibXML::Simple>,
Nicholas Clark backed the regressing change out and added some tests
to identify the problem so that that future attempts don't cause
the same breakage. Dave Mitchell said he had a cold, and was thus
unlikely to look at things for a while.

  get well soon
  http://xrl.us/oscv9

=head2 C<$*> is no longer supported

Rory Kingan was worried about some code that crawled out of the
woodwork complaining about C<$*> no longer implemented in 5.10.
Aristotle Pagaltzis looked at the regular expressions Rory
posted and concluded that it was just cargo cult code that could
be safely deleted.

  night of the living regexp
  http://xrl.us/oscwb

=head2 Milestone: metaconfig now under GIT

H.Merijn Brand thanked Sam Vilain and Abhijit Menon-Sen for helping
him get C<metaconfig> hosted entirely in git (at
L<http://perl5.git.perl.org/?p=metaconfig.git>), and declared its
Perforce branches officially closed.

  it's dead, jim
  http://xrl.us/oscwd

=head2 Syntax incompatibility (5.8.8 vs 5.10)

Edward Peschko wrote about a problem with C<Readonly::XS> that was
complaining about a use of C<Carp::croak>. This can be traced to a
decision taken over three years ago to remove the loading of C<Carp>
from C<warnings>.

Since the author of the module sees no reason to release a new
version of the module just to fix this problem, it is unlikely
that it will be fixed in the near future. Certainly there is no
desire to put C<Carp> back into C<warnings>, and
C<Perl::Critic::StricterSubs> can be used by authors to find such
problems (where client code loads module X, which in turn loads
module Y, and then the client code calls routines in Y without
having loaded it explicitly).

  EWONTFIX
  http://xrl.us/oscwf

=head1 TODO of the week

Here's a simple task that requires no C knowledge.

=head2 Fix tainting bugs

Fix the bugs revealed by running the test suite with the C<-t> switch (via
C<make test.taintwarn>).

(In fact, you don't even have to fix all of them, or most of them.
Just updating F<perltodo.pod> (patches welcome!) with the list of
problematic files would be a start).

=head1 Patches of Interest

=head2 C<icc> wants C<-fPIC> on x86_64

Vincent Pit offered a patch to get Intel's C<icc> compiling
XS modules correctly. Apparently this went nowhere.

  http://xrl.us/oscwh

=head2 F<Pod/Text.pm> Can't call method C<pod2text> without a package or object reference

Jari Aalto uncovered a problem in 5.10 with an undefined file descriptor
in C<Pod::Text>. He supplied a patch for it, which appears to be stuck
in limbo.

  http://xrl.us/oscwj

=head2 Don't reuse temp files in tests

Jerry D. Hedden found some more tests that had problems with names of
temporary file names being reused, so he changed them to use genuine
temporary file names. Jan Dubois pointed out that this was likely to be
a win for Windows systems that have on-access virus scanning, which can
interfere with files that are rapidly deleted and recreated.

  do not use a random method to generate random filenames
  http://xrl.us/oscwm

=head2 Show using C<waitpid> in C<IPC::Open[23]> SYNOPSIS

brian d foy noted that the documentation recommends using C<waitpid>
to clean up, but the supplied examples don't. So he amended them to
provide baseline best practices for people to use.

  do as i say not as i do
  http://xrl.us/oscwo

=head1 New and old bugs from RT

=head2 Volunteer for fixing the "Unicode" bug (#58182)

Back in August, when I was on my summ(?:ary|er) break, Karl Williamson
filed a bug report relating to the inconsistent handling of 8-bit characters
in strings during case mapping when no locale has been specified.

For instance, C<uc("\x{e0}")> returns itself (ŕ, or lowercase a grave)
rather than Ŕ (uppercase A grave). And this, regardless of whether there
are any multi-byte characters.

As a consequence, C<"\x{e0}" =~ /\x{c0}/i> fails to match. Moritz Lenz
explained that this was a known bug but unfortunately was not fixable
because too much code relies on the current behaviour (which Karl
summarises quite nicely in the original bug report). Moritz showed how
one could make things work, at the expense of a little make-work code
involving C<utf8::upgrade>.

Juerd Waalboer mentioned that it is fixable and scheduled for
implementation in perl 5.12, and that such backwards compatibility
issues have been noted in C<perl510delta>.

Dave Mitchell sketched out how one might go about producing an
implementation for this, which would involve breaking out the
semantically overloaded C<SVf_UTF8> flag from C<SvFLAGS> and
hanging it out in an auxilliary structure, which could be used to
store additional bits of information such as character set,
encoding, locales, UTF-8 caches and more, since there's no
space for such extravagances in a standard SV.

Juerd and Glenn Linderman weren't sure it this would end up being
a win. Glenn in particular thought that locale and encoding metadata
should probably be associated with file handles and the like.

  prologue
  http://xrl.us/oscwq

Fast-forward to this week, when Karl reported back to the list,
explaining that he'd implemented the change in behaviour in a 
copy of 5.10 source that seemed to do the trick, and asked the
list where to go from here. In a nutshell, his patch extends
ASCII semantics to the characters in the 128..255 Latin1
characters.

Glenn Linderman explained that Karl should use a pragma to
introduce this new change for code that wants to use it.

Rafaël amended this suggestion by saying that the Unicode
situation as it stands at the moment is such a mess that
no pragma would be required for 5.12: it would just Do The
Right Thing and backwards compatibility be damned. If the
change was back-ported to the 5.10 track, then a pragma
would be required in order to switch to the new behaviour.

Andreas König pointed out that Karl should base his patches
on blead, rather than 5.10. Rafaël said that starting a
branch from C<git://perl5.git.perl.org/perl.git> would be
as good a place as any from which to start.

Juerd thought that Karl should have no qualms about breaking
code with his changes, since a certain amount of reverse
breakage would may occur, whereby existing buggy code
suddenly begins to work correctly...

  famous last words "I just have to fix this bug"
  http://xrl.us/oscws

=head2 Building Perl 5.10.0 in AIX 5.3 using C<-Duseshrplib> option gives C<ERROR: Undefined symbol: boot_DynaLoader> (#58858)

Tippa found a problem that (s)he was able to fix by a minor tweak
to F<Makefile.SH> and so filed a bug report. Jan Dubois repackaged the
fix as a patch to F<makedef.pl>. H.Merijn Brand confirmed the problem
and the fix, and committed it as change #34379.

  AIX en provence
  http://xrl.us/oscwu

=head2 3-arg re-open drops IO layers (#58920)

Frank Meisschaert discovered that if STDOUT is redirected to a UTF-8 file
using the 3-argument form of C<open>, the UTF-8 layer does not get set. The
work-around is to close STDOUT explicitly beforehand.

Michael G. Schwern confirmed that the problem exists from 5.8.8 to 5.10.0
to blead on OS/X .

  not a team (p)layer
  http://xrl.us/oscww

=head2 C<grep unpack a/(a)> loops and eats all memory (#58942)

Ambrus Zsbán discovered a nifty way to have perl eat all available
memory. Nicholas Clark reported that the problem had already been identified
and fixed in blead. The correction will be backported to 5.10.1 and
5.8.9, which Nicholas said should be out within a month.

  that's not a feature!
  http://xrl.us/oscwy

=head2 Typo in CGI(3perl) man page (#59132)

Reuben Thomas identified two typos (in bug reports #59128 and #59130) which
were either already fixed in blead, or fixed thanks to his report. Reuben
found another typo in C<CGI>, for which Renée Bäcker produced a small
patch, although this will have to be pushed upstream to Lincoln Stein,
C<CGI>'s maintainer.

  meanwhile back at the CSHL
  http://xrl.us/oscw2

He also found a typo in C<File::stat> (filed in bug #59134).

  the proof is in the reading
  http://xrl.us/oscw4

=head2 Perl5 Bug Summary

Heading north. 268 new + 1032 open = 1300 (+6 -2)

  http://xrl.us/oscw6
  http://rt.perl.org/rt3/NoAuth/perl5/Overview.html

=head1 New Core Modules

=over 4

=item constant 1.16

Sébastien Aperghis-Tramoni uploaded what is essentially a
documentation fix. Applied to blead by H.Merijn Brand.

  http://xrl.us/oscw8

=item podlators 2.1.4

Russ Allbery fixed up the test suite to skip Unicode tests below
5.8, since C<Pod::Simple> doesn't support UTF-8 encoding with
those versions, and rearranged things to deal with Red Hat
C<ispell> idiosyncracies.

  http://xrl.us/oscxa

This followed 2.1.3, which was Russ's first attempt at addressing
error handling (emitting to STDERR instead of creating a POD ERRORS
section), along with the errors that H.Merijn brought up recently,
where an otherwise flawless smoke run was choking on UTF-8 locales.

  http://xrl.us/oscxc

=back

=head1 In Brief

Gábor Szabó chose C<Debug::Client> as the name for his B<client for
the built-in debugger>.

  now available on CPAN
  http://xrl.us/oscxe

Alexandr Ciornii set up B<dual life for C<Text::ParseWords>>. The
previous module on CPAN is 9.5 years old.

  now available on CPAN
  http://xrl.us/oscxg

Paul Marquess was worried about the complexities and potential for
breakage if he created a composite distribution that contains all
his B<C<Compress::Zlib> / C<IO::Compress::Gzip> / C<IO::Compress::Bzip2>>
goodness. Fortunately the solution is simple and robust.

  now available on CPAN
  http://xrl.us/oscxk

Michael G. Schwern reported on B<C<Method::Signatures> and the
C<\@foo> prototype>, and how nice it all was.

  now available on CPAN
  http://xrl.us/oscxn

=head2 Last week's summary

  http://xrl.us/oru8q

=head2 About this summary

This summary was written by David Landgren.

Weekly summaries are published on F<http://use.perl.org/> and posted
on a mailing list, (subscription: F<perl5-summary-subscribe@perl.org>).
The archive is at F<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.