This Week on perl5-porters - 6-12 November 2006
"*This is like sitting your mother down to teach her computers and
beginning by explaining little endian vs big endian and the intimate
details of protected mode memory*" -- Michael G. Schwern, firmly
believing that there must be a better way of installing perl.
Topics of Interest
INC handlers and "__FILE__"
(I didn't get around to summarising this thread last week).
Ron Isaacson had reported that he used code references in @INC, to
great effect, but regretted that the modules loaded no longer really
knew where they came from, "__FILE__" and related things would refer
to the module loader module, rather than their own paths.
Rafaél Garcia-Suarez concocted a quick fix in pp_ctl.c for "blead",
which improves the situation considerably. Glenn Linderman wondered if
a cheap and nasty hack, a "#line" directive at the top of each file,
could do as a temporary work-around.
Nicholas Clark suggested Ron take a look at an Acme module of his,
that might do more or less what he needed (see, sometimes Acme modules
*are* useful).
http://xrl.us/s5f7
Failures in /run/cloexec.t on Solaris and Tru64
The new t/run/cloexec.t test blew a bit of smoke out the O-rings. It
could mean that this is testing the operating system, rather than
perl, in which case it might wind up being removed. Andrew Savige,
father of the original patch, tried to teach it some manners.
http://xrl.us/tart
Building perl with VC++ 2005 (VC8)
Steve Hay, Steve Peters and Jan Dubois continued to work this week on
getting Visual C++ from Microsoft to compile the perl source, and had
lots of fun, or not, playing around with I/O, DLLs and the C runtime
library. By the end of the week all appeared to have been straightened
out.
http://xrl.us/taru
Later on in the week, Steve Hay started having problems with test
failures on a VC8 build. These were apparently due to problems in
interacting with (or rather, finding) the C runtime library.
After a bit of a discussion Steve was moving in the right direction.
http://xrl.us/tarw
Installing Perl shouldn't feel like a rite of passage
Michael G. Schwern felt that the Configure process was a bit too
verbose, asked to many questions, and sometimes gave some very scary
replies. He felt that it would be a good idea to be able to reduce the
verbosity level. Some way down in the thread, he showed the README
from Ruby, which, it must be said, is short, sharp, and to the point.
Andy Dougherty noted that the INSTALL file had amassed considerable
cruft over the years, due to various stupid bug reports that had
wasted considerable time of those doing front-line support at the
time.
Nonetheless, as Michael pointed out, the perl install process is
geared to catering for people with weird system setups, are in the
business of packaging Perl for distributions or are using it on
non-mainstream systems. The README and the Configure step reflect
this: it's hard to know what's important, and what's noise.
H.Merijn Brand felt that it might be worthwhile to put more emphasis
on Policy.sh, the idea being that if you've sweated out a
configuration trial-by-fire once, you can at least save that file away
in a safe place, and reuse it next time you build a perl.
At the end of a fairly long, but always interesting thread (lots of
good stuff from chromatic), Jarkko Hietaniemi injected a dose of
reality into the discussion, pointing out that "Configure" is not
going to be redesigned any time soon, it's hard to produce an
interface to it that makes end-user programmers and system
administrators happy, and so yes, to a certain extent it *will* be
difficult to avoid building perl from being a rite of passage.
655000 lines of C can't be wrong
http://xrl.us/tarx
Andy Dougherty produced an initial tweak to Configure to tone down the
*** WHOA THERE!!! *** messages to something a bit more laid back.
goodness gracious
http://xrl.us/tary
Jesse Vincent updated README to make it a little friendlier, and
feared that the resulting discussion would evolve into a discussion of
the colour of the bikeshed. Rafaël JFDI'ed the patch.
There were a number of useful suggestions made, and Michael reported
back that the target guinea pig for installing Perl liked the new
version.
http://xrl.us/tarz
Failures while attempting to install "Plagger" with bleadperl
Steve Peters was delighted to discover that Plagger has even more CPAN
dependencies than Catalyst or Jifty. Therefore, installing that one
module causes a large slab of CPAN to be pulled down and tested, which
is just the ticket when you're taking "blead" for a spin.
Alas, twenty eight modules failed their test suite, and three more
failed to build altogether.
Uh, could you run prove -vb on that, please?
http://xrl.us/tar2
Taking a look at the OS X hintfile for 10.4
Michael G. Schwern also thought that the hintfile for OS/X was rather
dusty, especially in terms of the 10.4 release, and thought that a
touch of spring cleaning was in order.
Andy Dougherty, Dominic Dunlop, Bo Lindbergh and Edward Moy had a look
at the issues, and it appears that the main ones are locales and
"poll()". Considerable head scratching and archive diving was
observed, and Andy hoped that the patch file would be commented with
pointers to this and other discussions, so that when the problem is
revisited, say, in 2011, it will be easy to zoom in on the previous
debate.
those who do not learn from history
http://xrl.us/tar3
Warnings from Pod/t/man.t in blead
It seems that "Pod::Man" is also falling foul of the new "Variable
length character upgraded in print" diagnostic. Rafaël fixed the
problem in "blead", but Russ Allbery noted that it wouldn't work for
"maint", as it uses modern "blead"ing features. He suggested a
possible "maint"-compatible technique, and wanted to know if it would
fly.
As proposed, the technique caused the tests on "blead" to fail, but
Rafaël produced a variant that should work on both codebases. It did
lead him to doubt whether the warning was actually useful in general.
Modern man
http://xrl.us/tar4
Chatting about sort sanity checking
David Nicol began to see how easy it would be to add warnings to catch
custom sort comparison functions that don't fulfill the contract of
what such a function is supposed to do (return a negative or positive
value, or zero). The low-hanging fruit would be to check for "<", ">"
operators and the like.
John P. Linderman thought this would be a good idea, but found it
difficult to reconcile with the constraint that there should be no
runtime penalty.
Out of sorts
http://xrl.us/tar5
MRO, sub_generation and so on
Brandon Black wrote "Class::C3", which provides an alternate technique
for method lookups, and he had come to the conclusion that for best
results, it needed to be more tightly integrated into the core (or
rather, the core needed to expose some aspects to the outside, that
his module could tap into).
Specifically, he had problems with the fact that a single change
somewhere can blow away the entire method name cache. What would be
nice would be to a way to blow away the methods on a per-package
basis, as it would less the cost of method cache invalidations.
Hugo van der Sanden was extremely interested in the approach, since he
has lots of code that creates methods on the fly, and this winds up
continually trashing the cache. Joshua ben Jore thought that "Moose"
and "Class::Trait" would benefit from the concept.
Nicholas Clark was somewhat sceptical, wondering how often people run
around adding new methods to code (once it's up and running, after
some preliminary initialisation phase). Be that as it may, he wasn't
particularly familiar with that part of the codebase, and suggested
looking through the lens of "perlbrowse", to find out *who* has been
working on that code in the recent past.
He did just that, and discovered that most of the code dates back to
beginning of the revision history, and thus the details are literally
lost in the mists of time. After taking another, closer look, Nicholas
was able to give Brandon some reasonable directions on how to proceed.
A new order
http://xrl.us/tar6
Perl Debugger resets the $main::{"_<$filename"} upon eval with a "#line
$filename" directive
Shlomi Fish found a problem with the debugger, that only showed up in
non-threaded 5.8.8 builds. After poring over the changes in
"perlbrowse", he was able to pin-point the likely culprits. Once this
legwork was done, it was a small matter for Rafaël to come up with a
fix.
Shlomi was most impressed, and asked if Rafaël had come up with a
test, to ensure that the bug didn't come back again. Rafaël admitted
to not being sure how to go about that, and Shlomi said that he had an
idea for one. So he produced a stand-alone test that did the deed, and
again it was a small matter for Rafaël to recast it in terms of a test
for the test suite.
debugging the bug in the debugger
http://xrl.us/tar7
24714 broke "Term::ReadLine::Gnu"
Andreas König discovered that a recent change to optimise lazy copying
in "sv_setsv()" caused "Term::ReadLine::Gnu" to go belly up. Nicholas
Clark rejigged the patch to restore the old behaviour to callers
outside the core, but Andreas still wasn't getting satisfaction.
http://xrl.us/tar8
Patches of Interest
New regexp syntax omnibus
Yves has been speaking with Larry Wall about the work on the regular
expression engine. Since all the new "(?..)" verbs do something quite
different to the older zero-width assertions, it makes sense to make
them look different. So now they are introduced by "(*...)". (Makes me
glad I haven't been writing code that uses them).
Anyway, the plot is beginning to be revealed at last. Yves wants to
build Perl 6 rules on Perl 5. This is going to be interesting.
Additional changes followed, and all of it wound up being landed in
"blead".
http://xrl.us/tar9
Joshua ben Jore was having trouble keeping Yves Orton's new regular
expression control verbs straight, since he kept getting mixed up with
Prolog. He also had trouble keeping up with the current thread dealing
with these matters, since he replied to a previous thread on the
subject. He thought that ERROR should become CUT, and CUT become
something else. Either that, or use whatever Perl 6 uses.
the hobgoblin of little minds
http://xrl.us/tasa
Static linkage for "perl.exe" for win32
Vadim Konovalov added a new target and few small tweaks to the Win32
Makefile, to allow a static perl.exe to be built (no more perl.dlls).
Steve Hay suggested better names for the resulting executable.
No more DLL hell
http://xrl.us/tasb
Vadim would really like to know how to push this patch forward, since
it would make his life a lot easier.
http://xrl.us/tasc
Make "s?printf" reject tainted formats
A few months ago, the idea was put forward that "printf"y format
strings should be subject to taint checks. Rafaël wrote the code to
implement this, and then stood back to see what people thought of the
concept. Dave Mitchell warmed to the concept and Johnathon Stowe
suggested that "strftime" ought to receive similar treatment.
Rafaél couldn't see how to abuse "strftime" effectively, so that was
left alone, but the code for the "printf" family went in.
taint fair
http://xrl.us/tasd
"Perl_die()" / "Perl_croak()"
Philip M. Gollucci finally scratched his itch and fixed up the
"printf" compiler attribute checks, by disabling them. This allows
modperl 2 to be built under "blead" again.
Robin Barker was under the impression that it is distressingly easy to
break modperl when working with "blead", and wondered if there was
some way of capturing in core tests the assumptions that modperl
relies upon.
http://xrl.us/tase
Make "if (%hash) {}" act the same as "if (keys %hash) {}"
Yves Orton noticed that, while semantically equivalent, testing for
%hash or "keys %hash" to see if a hash contains something do not run
at the same speed. He patched the core to make the former become about
as fast as the latter.
Rick Delaney reminded Yves to watch out for tied hashes, in case his
patch changed existing behaviour. Worse, using "if (%hash)" now resets
the iterator, which was more or less the final nail in the coffin for
the idea.
Yves then took a different approach, and created a new opcode
"boolkeys" to be used in this "if (%hash)" context, made it do the
right thing in the face of tied hashes, and as a result made it even
faster than using "if (keys %hash)".
faster %pussycat
http://xrl.us/tasf
New and old bugs from RT
localtime(3) calls tzset(3), but localtime_r(3) may not. (#26136)
Back in July, Benjamin Holzman supplied a patch to fix up the mess
when playing around with "tzset" and the "TZ" environment variable.
H.Merijn Brand dusted it off and applied it to blead as change #29209.
Yves Orton wondered whether it was good for Windows, since it caused a
number of tests to fail. Furthermore, it was unlikely to work in any
event, since recent overhauls to the environment variable handling on
Windows has decoupled the changing of environment variables within
Perl space from affecting the underlying C runtime library's notion of
the environment.
Sadahiro Tomoyuki suggested that the safest course of action was to
leave the code, and skip the tests on Windows, and supplied a patch to
do just that.
time on my side
http://xrl.us/tasg
"/^/m" doesn't match after a newline at the end of the string (#27053)
Yves then responded to a February 2004 bug filed by zefram, who didn't
like the behaviour of "^" in a certain context. He thought that while
it could be construed as a bug, it has since managed to become
sufficiently widespread to have evolved into a feature. While fixing
it would be theoretically good, it would cause a lot of existing code
to fail, starting with important pieces of the "Test::" namespace
itself.
This made Steve Peters ponder the idea of adding a "Won't fix" bug
status, which would allow bugs like this to be no longer counted
towards the open bugs total. Steve thought that a number of
auto-vivification feature-bugs could go this way as well.
sort of like unemployment statistics
http://xrl.us/tash
"Cwd::chdir()" and handles (#38466)
Steve Peters pinged Ken Williams on a patch for "PathTools".
http://xrl.us/tasi
"Data::Dumper" fails to dump all hash keys when iterator is not at start
(#40668)
Jerry D. Hedden fixed this bug, bumped the version, and Rafaël applied
it.
http://xrl.us/tasj
Bleadperl crash in Perl_pp_entersub() (#40681)
Steve Hay and Nicholas Clark got to the heart of the matter caused by
modperl 1.x blowing up on "blead". And when Nicholas finally came face
to face with the bug, he didn't know what the best way to solve it
would be.
http://xrl.us/task
Different behaviour of precompiled regular expression (#40684)
Claus Fischer reported a bug that Yves noted was already fixed in
"blead".
http://xrl.us/tasm
"Attribute::Handlers" not fully functional at runtime (#40695)
Johnpc discovered that attribute handlers don't work quite perfectly
for routines that are pulled in dynamically, via "require". His
work-around was to place the "require" in a "BEGIN" block. Rafaël
suggested trying a different approach, and asked if that would work
instead.
http://xrl.us/tasn
Weird behaviour in tainted hash with large integer, "SvIV/SvPV" mismatch
(#40708)
payerle wasn't sure, but he thought he had encountered a bug in Perl,
and so he filed a slightly apologetic bug report. Dave Mitchell
cheerfully confirmed that it was in fact really and truly a bug in
Perl. He simplified the code, and showed that 5.8.7 and blead gets it
wrong, but, somewhat miraculously, 5.8.8 gets right.
At this point, Dave punted, and asked Nicholas to take a look.
http://xrl.us/taso
perl parser bug leading to memory corruption/segmentation fault or
simply parse errors (#40718)
Dave Mitchell fixed the parser so that it no longer lost its mind.
http://xrl.us/tasp
Perl5 Bug Summary
22 up, 18 down, now 1539
http://xrl.us/tasq
http://rt.perl.org/rt3/NoAuth/perl5/Overview.html
New Core Modules
* Test::More/Simple/Builder 0.65
http://xrl.us/tasr
In Brief
Nicholas Clark uses an Intel-based Macintosh.
http://xrl.us/tass
Mike Schilli fixed a bug in SelfLoader.pm. Applied.
http://xrl.us/tast
Robin Barker worked on suppressing the "df" warning in stat.t on OS X
but Rafaël beat him to it.
http://xrl.us/tasu
But he was first to fix t/op/inccode.t failing under "minitest".
http://xrl.us/tasv
and silenced a signed/unsigned mismatch warning,
http://xrl.us/tasw
not once, but twice,
http://xrl.us/tasx
Rafaël made "Text::Wrap" warn less aggressively.
http://xrl.us/tasy
he also added a whole lotta goodness to "Attribute::Handlers", based
on last week's discussion.
http://xrl.us/tasz
Jarkko Hietaniemi made a couple of small tweaks based on smoke signs,
that is, errors produced in daily stream of smoke tests.
http://xrl.us/tas2
Michael G. Schwern uncovered a "blead" configuration that prevented
"strict" from being installed.
Not a feature
http://xrl.us/tas3
About this summary
This summary was written by David Landgren.
Weekly summaries are published on http://use.perl.org/ and posted on a
mailing list, (subscription: [EMAIL PROTECTED]). The
archive is at http://dev.perl.org/perl5/list-summaries/. Corrections
and comments are welcome.
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