"... because a git repository is a collection of assembled changes, not a linear progression, using a commit ID as a way to find out where your code came from doesn't work. This is not git's fault but is an issue with every distributed version control system (SVK tries to pretend otherwise). You could perhaps use a combination of the git repository you pulled from and the last commit ID, but [...] fundamentally the idea is gone. It's a small price to pay." -- Michael G. Schwern, coming to terms with the future.
$VERSION in Opcode The tangent regarding the issue of module version numbers and the
techniques to deal with them continued apace over the last fortnight.
The core of Matt S. Trout's argument over version.pm is that it
injects a method into UNIVERSAL, and this, in an of itself,
produces action at a distance, even when version.pm is not at
fault. The problem shows up when version.pm is used incorrectly
by third-party code, and the resulting errors are very hard to track
down.
All that being as it may, Matt appreciates the value of the version
comparison code available, and would like to be able to get at it,
while leaving UNIVERSAL untouched. Otherwise, it's akin to
modifying $[ or $/ at the global level. Tom Christiansen
concluded that only the highest level code should be putting
things into UNIVERSAL, not by proxy via the use of other
modules.
universal language http://xrl.us/oudw3 http://xrl.us/oudw5
Later on, in a particularly magnanimous gesture, John Peacock announced that he had a patch that would do all that Matt wanted and more, and asked if Matt was satisfied by it.
UNIVERSAL::VERSION and version.pm http://xrl.us/oudw7
Steve Hay took Michael G. Schwern's Y2038+ code for a spin in the land of Windows, and made a few adjustments to have it play nicely with the compilers there.
Based on Steve's recommendations, Michael produced a series of changes that ended up delivering sane results. In the end, Michael had to lift some code from the FreeBSD project to address the problem of converting strings to long longs. This helped the Microsoft compilers that still had not caught up with the C standard as of the previous millennium.
party like it's 1999 http://xrl.us/oudw9 http://xrl.us/oudxb
Later on Michael released a newer patch that included all his latest research on the matter. Steve continued to find a number of rough edges on Windows. H.Merijn Brand thought that it might be worthwhile probing for 64-bit variants of time routines on the platforms that offer them, since that the whole point of the exercise in the first place. And so he did, and said he'd get around to probing for the reentrant versions as well.
duty now for the future http://xrl.us/oudxd
Michael then had a patch working on Windows and Cygwin, contingent
on a couple of details that needed to be resolved. Some problems
turned out to involve the building of miniperl itself, which
uses some canned constants before Michael's work is able to work
its magic.
Dave Rolsky dropped by to say that he was delighted that all of
this work had a positive effect on the innards of Time::Local.
On the other hand, it greatly complicated the task of keeping it
dual-lifed on CPAN, so much so that he doubted that the new
changes would work with older perl releases. Michael showed him
how this could be done with some XS goodness.
just in time http://xrl.us/oudxf
vfork() (5.6.1 on Lamp) Joshua Juran is the caretaker for Perl on the traditional Mac OS
(that is, pre OS/X). Said platform doesn't know how to fork, but
it can vfork. In the current state of affairs, asking a program
to fork itself with something silly, like /dev/null, leads to
some very interesting (read: not useful) results, in that one
receives very little information as to what went wrong.
Joshua managed to get as far as showing how a minor change to
Perl_do_exec(), Perl_my_popen(), and pp_system()
would fix the problem, but he wasn't sure if his internals-fu
was strong enough to consider all the ramifications.
Nicholas Clark reasoned that the problem Joshua faced was sufficiently weird (or rather, his platform of choice was weird) that he should write the tests to establish the desired behaviour out on the end of the continuum, and then the rest of us could just follow suit.
Apparently he has done this on a code repository hosted on Sourceforge, but unless I am mistaken they didn't make it to the list.
pneumatic tubes http://xrl.us/oudxh http://xrl.us/oudxj
David Nicol responded to a previous thread (which I lack the tuits to track down) with the concept of polymorphism based on prototypes, which would, amongst other things, make the following work:
sub foo($$); sub bar(@);
bar foo 1, 2, 3, 4; # parsed as
bar( foo(1, 2), 3, 4);
He promised to investigate the possibility with his Macrame
module. In the meantime, Rafaël Garcia-Suarez reminded David
that prototypes in Perl are more for changing the syntax rather
that type inferencing.
http://xrl.us/oudxm
Torsten Förtsch discovered a problem that had crept into 5.10, which appears to be something to do changes to the implementation of stashes. No-one commented.
something new with :: http://xrl.us/oudxo
protochk and C++ Tony Cook had been puzzled for a while over intermittent smoke failures when using C++ on Debian, and managed to discover that C++'s function overloading mechanism was the cause. He suggested a change to a Configure test, but H.Merijn admitted that it was far outside his scope of expertise and asked for other eyes to look at it and consider the ramifications.
looking the other way http://xrl.us/oudxq
Nicholas, having endured a painful bisection ordeal under Perforce to track down when something changed, wondered what was holding up the migration to git. His current problem was one of mapping a Perforce revision (a number in a monotonic sequence) to a git checksum.
Mark Mielke wanted to know if there was a page on the web somewhere that recorded the current status of the Perforce-git migration.
Michael G. Schwern offered an interesting parenthetical remark regarding the move from Perforce to git, and why it is the Right Thing. David Golden also noted that git solves the problem of branching at any point in time, hacking, and folding the changes back in a most elegant manner. The price you pay, though, is that it is very hard to point to a specific moment in development (since one only has an unsortable checksum, not a monotonic sequence).
Craig A. Berry, not fully versed in git-speak, was nonetheless able to describe how people would communicate points of interest in the development tree. At the same time, he thought that the barrier to entry to understanding git was much higher than that of Perforce. As it turns out, basic web projections of git repositories already come close to what the All Perl Changes browser provides.
gitting there http://xrl.us/oudxs
Michael went through the git threads on the list and neatly summarised them on the Perl5 wiki. He noted with satisfaction that there were no showstoppers, just a question of tuits.
http://xrl.us/oudxu
Perl_newSVpvf("%lld") is broken One other item that fell out of the Y2038+ code was that, on
32-bit platforms, printf("%lld\n", 2**32) gives a result
of -1. Michael and admitted to being terrified by the code and
hoped someone else could dig down through it and figure out
where the problem lay.
quad wrangle http://xrl.us/oudxw
Nicholas Clark looked more closely at Matt Kraai's failures for
5.8.9-tobe on QNX. He determined that it was due to a refactoring
of File::Spec::Unix::abs2rel between Pathtools 3.12 and 3.13.
Interestingly, this dredged up an interesting piece of Perl
trivia, in that for a short time, the /t flag on a regexp
match maintained the taint flag if the target string was
tainted. The idea lived a short life.
Nicholas thought that creating a new File::Spec::QNX (and the
like), since it would be easier to test and would probably
simplify the implementation of catdir. In any event, he
wrote a patch and Matt confirmed that it fixed up the problem
on QNX 6 (a.k.a QNX Neutrino, or $^O eq 'nto').
Ken Williams folded Nicholas's patch into his Pathtools repository.
http://xrl.us/oudxy
Nicholas Clark uncovered a flaw in Same Vilain's Perforce-git import. Sam said he'd go over the import code to see if he'd missed anything. By and large most of the Perforce branches were bit-for-bit perfect.
ancient history http://xrl.us/oudx2
Nicholas produced another snapshot of 5.8.9-tobe. Of note were
some problems on VMS (for which fixes existed) and some minor
problems with Module::Build.
Slaven Rezic tested some 3700 CPAN distributions and listed a dozen or so regressions. Most of them turned out to be minor, but one was an honest to goodness C error, relying on a reallocated SV landing in exactly right place.
getting closer http://xrl.us/oudx4
Nicholas Clark wailed and gnashed his teeth at vendors who
insist on foisting a perl compiled with -DDEBUGGING upon
their users, and pondered tweaking things to make it produce
a nasty warning on STDERR during startup.
make it so they have to reboot http://xrl.us/oudx6
Abigail wondered how to deal with a test that causes a segfault
during program exit, since even a fresh_perl_is from test.pl
will return a correct result, not seeing that $? contains a
non-zero value. Michael G. Schwern thought that the expedient
measure of testing $? against zero should be sufficient.
measuring success http://xrl.us/oudx8
A task that need a little sysadmin-type knowledge
Some platforms mandate that you provide a list of a shared library's
external symbols to the linker, so the core already has the
infrastructure in place to do this for generating shared perl
libraries. My understanding is that the GNU toolchain can accept
an optional linker specification file, and restrict visibility just
to symbols declared in that file. It would be good to extend
makedef.pl to support this format, and to provide a means within
Configure to enable it. This would allow Unix users to test that
the export list is correct, and to build a perl that does not pollute
the global namespace with private symbols.
Vadim Konovalov continued to deliver his patches for cross-compilation. Alas, few people with commit bits have had the time to review them and enter them into Perforce. There is hope that git may alleviate these sorts of problems.
http://xrl.us/oudya http://xrl.us/oudyc
Ben Morrow reported on the test failures on Interix for 5.8.9-tobe. Jan Dubois took issue with the skipping of tests, since that might lead the underlying bugs to be swept under the carpet. Ben thought that there was a distinction to be made as to whether the test suite was testing Perl or Perl and its interaction with its host environment (such as bugs in the C library).
Rafaël hoped that the changes, if they were good enough for 5.8, could also make it into blead. Ben saw no reason why not, he just wanted to help get 5.8.9 out the door at the moment.
http://xrl.us/oudye
Nicholas continued to ponder what Vincent Pit had uncovered, regarding an off-by-one allocation in the regexp compiler.
http://xrl.us/oudyg
-Idir option on the command line and shebang (#6665) Renée Bäcker wondered why using -I on the shebang line of a Perl
program appends the specified directory to @INC, rather than prepending.
Rafaël Garcia-Suarez explained how and why it was a feature, and Renée
proposed a patch to make -I always prepend.
http://xrl.us/oudyi http://xrl.us/oudyk
return do { }: take 3 (or 4...) (#38809) sub foo { do { return do { 1; 2 } }; 3 } returns undef. This is unfortunate.
Vincent Pit has been chipping away at the problem, trying to solve it. This
is his latest offering. He's still not happy with the fix, and suggests that
it's either this, or ignore the bug.
tests will tell http://xrl.us/oudyn
Bob Peterson called for help in getting a new Perl running on a very, very
long in tooth SunOS platform. Andy Dougherty thought that the last time he
had attempted such a task was in 2001, and thought that some of the errors
Bob was encountering were due compiler bugs, and that building without
-O2 optimisation may alleviate some of the problems.
Nicholas Clark identified some failures as being Mostly Harmless, but others were rather more disconcerting.
teaching an old dog http://xrl.us/oudyp http://xrl.us/oudyr
Unicode::UCD::casefold() does not work as documented, nor probably as intended (#58430) Karl Williamson continued to work on Perl's simple-minded implementation of folding case for Unicode characters, the real-world problems that this induces, and a proposal on how to move to something that works whilst retaining backwards compatibility.
Rafaël asked for some background for the readers following along at home, and Karl responded with a very well written summary of the problem domain.
all you need to know http://xrl.us/oudyt
Eirik Hanssen and Alexandr Ciornii pinned down some code that failed in Strawberry Perl 5.10.0 and wondered if it was common to all Windows 5.10 builds. Cygwin and Unix builds appeared to be unaffected.
broken windows http://xrl.us/oudyv
Robin Hill offered an interesting bug on 5.10 that proceeded to eat all memory. The trigger was a regexp with a quotemeta'ed portion and some single character character classes.
Nicholas Clark noted that while lots of memory gets chewed up, if the program is able to run to completion, every last byte is correctly freed. Dave Mitchell produced a smaller test case to demonstrate the leak... which still cleaned up after itself if things ended in an orderly fashion. Believed (by Nicholas) to be solved.
http://xrl.us/oudyx
$ is left off $last (#59522) Inside a curly brace block, even just for lexical scoping, last
will take you out of it without a murmur, even if you write $x < last
instead of $x < $last. Unfortunately there's not a whole lot
that can be done about it.
http://xrl.us/oudyz
readline returns EBADF at eof in 5.10.0 (#59550) Mark Martinec reported that the readline() function (or a diamond
I/O operator <>) returns a EBADF (Bad file descriptor) as its errno
status on end-of-file when PERLIO is set to "stdio".
http://xrl.us/oudy3
Leandro Gregorio needs some help with an installation on a 64-bit Linux platform.
http://xrl.us/oudy5
\x, \0, \N{U+....} (#59616) Karl Williamson is now using the latest version of blead for his work and is pushing out the bugs he encounters in Unicode case folding. His latest item is that specifying characters in hex, octal or named characters defeats the regular expression engine.
http://xrl.us/oudy7
@INC (#59626) Shawn Moore wanted to be able to profile code references in @INC
via Devel::NYTProf, and found a number of hurdles in his way.
He offered a patch that appeared to work, but Nicholas Clark pointed
out that it did in fact only appear to work, and making it work would
in fact be much more difficult.
http://xrl.us/oudy9
Karl Williamson continued on his Unicode trek this fortnight, with a summary of the issues concerning this bug (for which the main point is about how to land it gracefully in 5.10 in a backwards-compatible manner, switchable via a lexical pragma). Another item is what to do about regular expressions which are compiled in one (Unicode-encoding) context and then used in another.
Glenn Linderman and Rafaël made a few comments, and it appears that Karl has managed to reach a concensus of sorts.
http://xrl.us/oudzb
unicore/mktables expects wrong syntax from CaseFolding.txt for Turkish (#58656) Karl pinned down the bug in Turkic character handling in Unicode. In his words: "it appears that the Unicode folks decided they were doing the wrong thing in 3.1, and changed it in 3.2. Perl is still looking for the 3.1 syntax." That is, they snuck it in without telling anybody. Karl hopes to be able to produce a patch.
http://xrl.us/oudzd
File::Copy does not handle file objects sanely (#59650) Wow, another bug in File::Copy.
http://xrl.us/oudzf
Either that, or too early, since no-one has the tuits to implement something that would do the right thing. In the meantime, Aristotle Pagaltzis proffered the canonical workaround.
http://xrl.us/oudzh
Salvador Fandiño found a way to make things go boom. But what could that pattern be used to match?
6000 parens is not enough http://xrl.us/oudzj
Cwd::realpath fails on unsearchable directory (AIX) (#59662) John Wiersba showed that a short C program worked where Perl fell over and choked.
just need to cut'n'paste http://xrl.us/oudzm
(?|) in regexp. (#59734) Abigail gives the regexp engine indigestion, with a short, sharp
perl -wE '";" =~ /(?<a>(?|(?<b>;)))/;' to the ribs.
new toys broken http://xrl.us/oudzo
Paging Tels. White courtesy phone.
unless fixed in blead? http://xrl.us/oudzq
File::Find behaviour with files among @DIRS (#59750) J. Flack noted with pleasure that File::Find does more or less
the right thing when given a file as a starting point. And in fact,
if it didn't, it would be incredibly awkward to make it so from the
client side.
Unfortunately, it is completely undocumented, so his/her plea was to have it documented so that it could be relied on, unless perchance it doesn't work at all on some obscure platform.
when you need it, you need it bad http://xrl.us/oudzs
Markus Huaraz filed a bug report on Linux regarding the setting of $>
preventing perl from reading its own binary. The /proc symbol table
entered the picture, but Rafaël Garcia-Suarez was unable to reproduce
the problem.
note to self http://xrl.us/oudzu
Andreas König reported a smoke failure and suggested the fix (in
ExtUtils::MakeMaker).
http://xrl.us/oudzw
Whilst working upon the next release of Regexp::Common, Abigail
encountered some flaws in the implementation of (?|) and offered
some tests to pin down the problem.
broke again http://xrl.us/oudzy
Nope, just symbolic references that use strict would have caught.
priceless http://xrl.us/oudz2
return 0 or die (#59802)
return doit() or die "did it wrong";
It would be nice if that warned "unreachable statement".
that or Perl::Critic http://xrl.us/oudz4
279 new + 1054 open = 1333 (+15 -5) http://xrl.us/oudz6 http://rt.perl.org/rt3/NoAuth/perl5/Overview.html
http://xrl.us/oudz8 http://xrl.us/oud2a
http://xrl.us/oud2c
http://xrl.us/oud2e
http://xrl.us/oud2g
http://xrl.us/oud2i
Renée Bäcker pointed out that there are many patches in RT bug reports, just begging to be applied.
http://xrl.us/oud2k http://xrl.us/oud2n
Michael G. Schwern suggested an improved GM/LOCALTIME_MAX/MIN search
algorithm. H. Merijn Brand suggested a tweak or two.
http://xrl.us/oud2p
Jim Cromie was stung by list context in assignment.
bad luck http://xrl.us/oud2r
Michael G. Schwern discovered that HP's Testdrive being replaced. As a long-time resource for testing VMS issues regarding Perl, it will be greatly missed. The HP engineer that H.Merijn contacted suggested that something could be worked out.
thanks for all the fish http://xrl.us/oud2t
Nicholas Clark wasn't sure if CPAN bug #39403 involved something that needed to be fixed in the core (the ability to overload or intercept an attribute, other than using a source filter).
http://xrl.us/oud2v
Nicholas also proposed a wild-assed guess to allow parallel testing on Win32 but Steve Hay reported no joy. Andy Armstrong understood the resulting symptoms sufficiently to volunteer to see if he could figure out why.
http://xrl.us/oud2x
Salvador Fandiño noted that Paul Fenwick was not the first person
to whether the prototype for CORE::truncate is wrong.
http://xrl.us/oud2z
Nicholas removed the missing type VSTRING in the
documentation to ref since it wasn't supposed to be there at
all, being an overly optimistic backport from blead.
bug #59264 solved http://xrl.us/oud23
John O'Rourke ran into some odd behaviour of substr(lc($utf8))
in 5.8.8 that Nicholas had fixed, he thought, thanks to a TPF grant.
Since that work had made it to 5.10 and had been backported to the
upcoming 5.8.9, he was happy to leave things there.
http://xrl.us/oud25
Nicholas noticed some make distclean failures, in that there
were some files left over from a run of the test suite that weren't
cleanup up after the target was run. Andy Armstrong began to look
at cleaning things up, since he had a nagging suspicion that a
number of them might be his fault.
http://xrl.us/oud27
H.Merijn Brand released Data::Peek to CPAN.
a collection of low-level debug facilities http://xrl.us/oud29
Nicholas saw a Debugger saved lines regression and wondered out
loud what was the new officially sanctioned way of noting new
subroutines that are defined during an eval. When the right
technique is found, a test he wrote should begin to pass.
http://xrl.us/oud3b
If Dave Mitchell is ignoring you, resend your message.
the tale of davem's lost emails http://xrl.us/oud3d
This Week on perl5-porters - 15-21 September 2008 http://xrl.us/oud3f
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.