"I'm really tempted to fix toke.c:S_incline() instead. I don't think
there will be much breakage, right?" -- Rafaël Garcia-Suarez,
hiking in mountain boots where angels fear to tread.
Matt Kraal reported what tests on 5.8.9-tobe were failing on QNX, and when prodded by Nicholas Clark, produced the delta regarding the tests that were already failing on 5.8.8.
no showstoppers http://xrl.us/osxd6
$VERSION in Opcode Matt S. Trout revived the thread about Opcode and Safe by
talking about version.pm, saying it was a really nice module, just
a shame about it messing with UNIVERSAL. When John Peacock showed
him the scars of six years working to make version comparisons work,
and asked for a test case to show where it didn't work, Matt skirted
the issue by saying that he really liked version.pm's version
comparison code, and would John accept a patch that switched off
the UNIVERSAL hackery.
like a version http://xrl.us/osxd8
Reini Urban mentioned that he was carrying out research to restructure the way opcodes carry around the original source line number (for eventual error reporting). First results seemed to indicate that reasonable code could expect to see an 8% speed increase.
Dave Mitchell saw that the main thrust of the work was to do away
with nextstate ops, and warned that one of their other purposes,
apart from carrying around line numbers, was to give the interpreter
an opportunity to clear out the temps from the stack.
Ben Morrow wondered whether the place where the clearing out took
place could be moved from pp_nextstate into Perl_runops_standard
et al instead. Reini thought it wouldn't be necessary, since he
was identifying nextstate ops that do trigger temps housekeeping,
and he wasn't touching those.
all lined up http://xrl.us/osxea
Thomas Karcher was having problems with perl installations on two different Xen VM machines, which, while nearly identical, were producing two very different results. Despite a couple of good suggestions from Nicholas Clark, no good answers turned up.
the art of vm maintenance http://xrl.us/osxec
DDump H.Merijn scratched the same itch twice in the space of a week
regarding the ability to dump a scalar in excruciating detail (using
a secret handshake involving sv_dump) à la Devel::Peek within
Data::Dumper, and so wondered whether he should keep it to
himself, or push the changes outwards either as a CPAN module or
somewhere within core.
Nicholas Clark thought that that the concept was sound although he
took issue with pumping the results out to a file handle, and thought
it would be better to send it to a scalar, as this gives the client
more flexibility in deciding what to do with it. This would require
changes to all the *dump routines. Graham Barr thought that it
would be easier to define new API entry points that performed the
existing dumps to a scalars.
In the following discussion, H.Merijn applied a number of changes
that fixed various problems that, alas, my time budget does not
allow me study in greater depth, but he concluded that the changes
where worthy of backporting to the 5.10 branch, and that more tests
were needed for the *dump family of functions.
a better dump http://xrl.us/osxee
This work wound up producing failure in XS::APItest, that Steve
Hay eventually fixed.
http://xrl.us/osxeg
Abigail observed that perlhist had acquired over six years of bitrot regarding the statistics of perl test releases, and wondered whether it was better to bring it up to date, or delete the information altogether. Moritz Lenz voted for bringing them up to date, citing a love of statistics.
Tom Christiansen had also noted the oversight in the recent past, but wasn't sure whether this was a result of official policy or just something that had slid under the radar.
Yitzchak Scott-Thoennes also weighed in saying that it would be Good and hoped that Abigail would find the tuits to do so.
fun with numbers http://xrl.us/osxei
Richard Foley sent in a draft for a document on Perl Performance and Optimization Techniques (or PPOT). H.Merijn suggested merging in the points covered by Nicholas Clark's "When Perl isn't fast enough" talk.
Reini Urban took the time to fill out the SEE ALSO section with modules on CPAN that deal with performance issues. Tim Bunce suggested another place to dig up some nuggets.
The discussion naturally zeroed in on Devel::DProf, that
Time Bunce declared was broken (and no-one contradicted him) and
said that Devel::NYTProf was in all ways superior.
Nicholas Clark thought so too, but wondered if NYTProf would be ready in a year or so for freezing within the official distribution. He also thought that the NYT (New York Times) aspect was of great marketing value to show who used and contributed to Perl, in contrast to Richard Foley's idea of renaming it to NGProf for "New Generation".
Rafaël Garcia-Suarez greeted the inclusion favourably, but noted that it is (still) rather Windows-unfriendly and contains some rather unportable code. Interestingly, this was the first time I can recall that the core developers stated that a perfectly valid reason for removing a module from the core is that it's always available on CPAN for those who depend on it.
Richard then released a second version, based on the feedback received so far. It will be added to the core. Eventually.
Do Not Engage in Useless Activity http://xrl.us/osxek
David Landgren (err, I) was stung by not knowing Perl sufficiently well and wanting to write
my @want = @{[ my $rand = rand(); $rand < 0.5 ? 'pie' : 'beer' ]}
not realising that what goes between [ and ] is an expression
and not a series of statements. The problem is that Perl's parser
can do little more than a CP/M BASIC-era "Syntax error" message,
which conveys insufficient information to determine the nature of
one's sins.
Nicholas Clark devoted the time to figuring out that what needs to
be done is to teach the tokeniser to react to encountering a ;
token within an expression and acting accordingly.
http://dilbert.com/strips/comic/2001-10-25 http://xrl.us/osxen
Chris "BinGOs" Williams was playing around with Mir OS (an OpenBSD fork) after having read about it in Michael G. Schwern's use.perl blog (search engines take note: Michael G. Schwern has a Perl blog on use.perl.org). He discovered that the developers there had created a hints file. He pushed it up to the porters, and Nicholas folded into the codebase, berating all the while the package maintainers of the world who choose to live in autarky.
a bell is a cup until it is struck http://xrl.us/osxep
Here's a task chosen entirely at random that requires a certain amount of C knowledge, and would be a delightful task for someone wishing to learn a bit more about how the parser works.
[$b; $c] Using ; inside brackets is a syntax error, and we don't propose
to change that by giving it any meaning. However, it's not reported
very helpfully:
$ perl -e '$a = [$b; $c];'
syntax error at -e line 1, near "$b;"
syntax error at -e line 1, near "$c]"
Execution of -e aborted due to compilation errors.
It should be possible to hook into the tokeniser or the lexer, so
that when a ; is parsed where it is not legal as a statement
terminator (ie inside {} used as a hashref, [] or ()) it
issues an error something like ';' isn't legal inside an expression
- if you need multiple statements use a do {...} block. See the
thread starting at http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2008-09/msg00573.html
(or the thread summarised elsewhere in this issue. Consider it a fringe benefit that goes with the job).
Michael G. Schwern sent the heads-up on his ongoing work to make Perl deal correctly with dates beyond 2038 (which would otherwise overflow the underlying 32-bit storage used). He was delighted to receive some Windows feedback from Steve Hay, and asked for the changes to be folded back into blead in order for the code to receive wider cross-platform exposure.
crossing the date line http://xrl.us/osxer
DosGlob to work with paths containing ()'s Alex Davies taught DosGlob to deal with filenames that contain
parentheses. This is important on Windows where one often encounters
files names of the Copy (2) of foo nature. Shlomi Fish suggested
that a test-case would be a nice addition to the patch, as it
would have caught a problem in Alex's own patch.
touché http://xrl.us/osxet
Vincent caught another puzzling bug in 5.8 with threads that appeared to be simple off-by-one sizing error. Nicholas Clark thought that the code was identical as far as he tell to that of blead, and yet there was no problem there. There were other puzzling symptoms that made Nicholas suspect there was something deeper afoot, but couldn't see how to coax the problem out into the open.
by the pricking of my thumbs http://xrl.us/osxev
Whilst working on his Y2038+ code, Michael G. Schwern discovered
that reentr.h was riddled with #ifdef foo/#endif # bar that
didn't line up, so he straightened them out.
comment rot http://xrl.us/osxex
Thomas Karcher discovered the hard way that Perl doesn't have a fine-grained locking method for shared arrays with threads, but wasn't sure if this was a bug or a feature.
arrayed against him http://xrl.us/osxez
Glenn Linderman kindly provided the leads to track down previous p5p threads on the issue of Unicode implementation issues in Perl 5. He also identified the list of contentious operators and operations performed with Unicode data.
One important point Glenn raised was that Windows filenames and Unicode do not get along well, since Perl doesn't use the UTF-16 system APIs. Changing this will cause pain, but it currently prevents people from writing multi-lingual applications on Windows in Perl.
http://xrl.us/osxe3
Father Chrysostomos tracked down another regular expression bug in the upcoming 5.8.9 release. Nicholas Clark traced this back to change #30638, that Yves Orton had written for blead to fix bug #39583.
http://xrl.us/osxe5
#line directive in perlsyn. (#59170) Elliot Shank found a typo in the recipe given for determining
filenames and line numbers when decoding #line directives. He
suggested changing the regular expression to make it correspond
with what really happens under the hood. Rafaël Garcia-Suarez
suggested that it might be better to fix the tokeniser in order
to make it match the documentation, as what it purports to
document is more useful than how things behave currently.
fight the cause http://xrl.us/osxe7
Phani Kancharia reported a distinct lack of success in configuring perl on a big endian MIPS64 platform. The problem was that there is a paucity of information in the hints/mips.sh file; so much so that the configuration probes are unable to determine a viable strategy for dealing with 64-bit integers. H.Merijn Brand hinted that it might take a significant amount of work to get things into a usable state.
http://xrl.us/osxe9
Andy Dougherty uncovered a problem revealed by a change made in September 2007. Nicholas regretted that a similar test for 5.10.0 would have picked up the problem much earlier, but corrected it anyway.
wholly undynamic loadings batman http://xrl.us/osxfb
Andy Dougherty discovered that the test suite Dynaloader itself
fails if perl is configured without dynamic loading, and suggested
that it is largely due to trivial differences in error messages.
Nicholas Clark fixed things up with change #34404.
http://xrl.us/osxfd
Hans Ginzel reported an inconsistency with ref, Renée Bäcker
offered a documentation patch to clarify the matter.
http://xrl.us/osxff
PerlIO::via leaks memory at a high rate (#59268) Marc Lehman produced one leak per write using the via PerlIO
layer. His hypothesis is that newGVgen leaks.
http://xrl.us/osxfh
Luke Ross uncovered an inefficiency with push on tied arrays,
and proposed a patch to attempt to address the problem. Eric Brine
pointed out that subroutines (and hence, modules) that return values
by accident when called in void context would break with Luke's
change, not the least of which is Tie::Array.
Luke returned with a variant that seemed reasonable to Rafaël,
who thought that, by extension, the same reasoning could be applied
to unshift. So Luke returned with a third variant that took
unshift into account as well. And things stopped there for the
moment.
when push comes to unshift http://xrl.us/osxfj
/\N{U+...}/ fails to compile properly if ... is > 256 (#59328) In his quest to fix Unicode, Karl Williamson noted in passing that
$foo =~ /\N{U+257}/ does bad things to S_reg_namedseq().
(Summariser's note: in trying to reproduce this, I was unable to
coax any sort of error message. Methinks more context is required).
http://xrl.us/osxfm
Nathan Reed asked for help after failing to configure perl 5.10 on Solaris. H.Merijn Brand and Andy Dougherty diagnosed a problem of user defined configuration removing /usr/lib from the list of paths used to resolve C library references.
http://xrl.us/osxfo
Karl William noted another bug in passing as he proceeded in his work. Abigail and David Nicol weighed in explanations and suggestions, but Karl replied that it wasn't of great importance since he expected his ongoing work to resolve it anyway.
http://xrl.us/osxfq
Marc Martinec stumbled over a change in 5.10 involving qr//'ed
regular expressions embedded in other expressions when /m was
added to the mix. Rafaël explained that this fixed a greater
problem.
it's a feature http://xrl.us/osxfs
Karl also noted that "\xe0" =~ /[\x{100}]/i is parsed incorrectly.
http://xrl.us/osxfu
Mark Pack discovered a very obscure corner case on a non-matching substitution nevertheless causing a change upon a scalar holding a floating point value.
Nicholas Clark correctly identified the problem as one of unintended stringification, and amended Mark's regular expression to not match unintentionally, thereby avoiding the stringification, and all was well. He went onto explain that Mark wasn't exactly wrong in his analysis, but to do as he suggested would incur a generalised cost to every single match, whether it applied to Mark's corner case or not.
a matter of comprise http://xrl.us/osxfw
267 new + 1038 open = 1305 (+9 -4) http://xrl.us/osxfy http://rt.perl.org/rt3/NoAuth/perl5/Overview.html
Ken Williams announced the release of 0.30. There was a certain amount of discussion as to when it would support autobundling.
Steve Hay had a bit of trouble applying this to blead as there was a bit of fuzz in terms of things in blead that weren't in 0.30 as it stood.
This then segued into a discussion of Archive::Tar having some
problems outstanding on VMS. To this, Jos Boumans replied that an
all new 1.40 version of that module should be released soon.
http://xrl.us/osxf2
Michael G. Schwern announced that he had dragged ExtUtils::MakeMaker
into the third millenium of additional metadata to allow modules
to boldly qualify themselves where no modules had gone before (unless
they used Module::Build). Specifically, it now adheres to the 1.4
version of the META.yml specification.
Here too were revealed problems of changes in blead not being in the module's own development repository.
the module that would not die http://xrl.us/osxf4
Sébastien "Maddingue" Aperghis-Tramoni delivered the latest
version of XSLoader, that all the cool kids use a replacement
for Dynaloader, to deal gracefully with the uncool kids who
don't do dynamic loading.
http://xrl.us/osxf6
Rafaël Garcia Suarez added Shlomi Fish's addition of open "|-" and
open "-|" to perlopentut .
http://xrl.us/osxf8
Gábor Szabó's quest for a name of a debugger client reminded Matt
S. Trout about Devel::ebug, which he thought already implemented a
certain amount of what Gábor was trying to do.
http://xrl.us/osxga
Landry Breuil reported two regression tests failing on OpenBSD/sparc64. Rafaël Garcia-Suarez thought that 32/64 bit inconsistencies might be the reason.
http://xrl.us/osxgc
Karl Williamson had asked What do I do when I stumble upon an existing bug while I'm working on other changes? and the answer should be obvious upon reading this week's "New and old bugs" section.
http://xrl.us/osxge
Jerry D. Hedden reminded Nicholas Clark that he needed to propagate change 34377.
http://xrl.us/osxgg
He also simplified the loading modules in test.pl .
http://xrl.us/osxgi
15-21 September 2008 http://xrl.us/osxgk
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.
I had difficulties over the past few weeks loading the summaries but things appear to be fixed now, which is why the last four are missing. Would people be interested in reading them if I post them, even if they are out of order?
Yes please.
grantm on 2008-10-06T20:42:17
I definitely would be interested. Maybe you could just add a short note about the ordering to avoid confusion.