This Week on perl5-porters - 17-23 April 2006
Topics of Interest
Redoing the regular expression API
Yitzchak Scott-Thoennes suggested that Yves Orton send in a patch to
pull out some of the ancillary functions in "Data::Dump::Streamer" in
order to make them available in the core distribution.
http://xrl.us/k2x7
So Yves did just that. The first addition is to add "reftype_name()",
that behaves like "reftype" except that it returns false rather than
"undef" on non-references. This removes the need for fussy make-work
code on the client side to avoid warnings.
The second addition is a "regex()" function, which makes it easier to
deal with patterns, whether they have been blessed into other
namespaces or not.
Graham Barr admitted that the return value of "reftype()" was a
mistake, and "reftype_name()" was acceptable, but felt that the
"regex()" function was better off in the "Regexp" module.
Yves didn't like the fact that "Scalar::Util::reftype" returns
"SCALAR" instead of something like "REGEX". Nick Ing-Simmons liked the
idea, but thought that it was too dangerous for "maint".
Another sub-thread in the discussion revolved around whether a qr//
thing is an object or a type. It is, in fact, an object, but Yves
argued that it is much more useful to treat it as a type. Graham
agreed to disagree.
Adam Kennedy admitted to using "Regexp"s as objects quite a bit and
would be happy to see the "Regexp" module receive a dose of
spring-cleaning (which I suppose means fixing up the reblessing
inconsistency that Yves was getting at).
Another hassle Yves pointed out was the non-reversibility of
stringifying regexps:
my $qr=qr/foo/;
my $str="$qr";
print qr/$str/; # equivalent but not equal
Dave Mitchell pointed out that a regular expression currently *is* a
scalar, it just happens to have a bit of magic attached...
Shouldering the weight of history
http://xrl.us/k2x8
Silly regexp tricks
Hugo van der Sanden returned to the super-linear cache bug (a "||"
logical or instead of a "|" bitwise or) in the regular expression
engine, and came up with a suitable test case:
("a" x 31) =~ /^(a*?)(?!(a{6}|a{5})*$)/;
print length($1);
This prompted Yitzchak Scott-Thoennes to come up with another bug that
showed how "blead" broke existing behaviour. Since no-one should ever
have come to rely on this behaviour, it was all quietly swept under
the rug. Dave Mitchell hinted that he was working on New Stuff in the
engine.
http://xrl.us/k2x9
Bringing "threads" into the third millenium
Jerry D. Hedden continued to send patches to sync CPAN's "thread"s
with "blead", first by removing a superfluous counter.
http://xrl.us/k2ya
and again
http://xrl.us/k2yb
and reworked the threads destruct call
http://xrl.us/k2yc
He vented his frustration at the slow pace with which the patches were
getting applied, believing that he was playing by the rules as much as
possible. Rafael was very apologetic, explaining that he understands
so little about threads that he's barely qualified to apply them. And
apart from Rafael, there aren't too many alternatives.
http://xrl.us/k2yd
Backporting the new "blead" RE improvements to "maint"
Nicholas Clark posted a proof-of-concept update to re.pm to deliver
Dave Mitchell's iterative (as opposed to recursive) implementation of
the regular expression to perl 5.8.1 and beyond. A few show-stoppers
need to be cleaned up: some coredumps in the test suite need to be
sorted out and some tweaks to ppport.h are needed. As a bonus, Yves
Orton's trie work comes along for the ride.
More songs about building regexps
http://xrl.us/k2ye
"valgrind" and Perl 5
Nicholas Clark wondered what would happen, as in, how many bugs would
be uncovered, if one were to run the test suite under "valgrind". So
Rafael Garcia-Suarez did just that, and discovered that 41 test files
produce errors.
Nicholas and Rafael then set about fixing up the problems that were
uncovered.
There's always something to do
http://xrl.us/k2yf
Better reporting of TODO tests
Nicholas Clark looked at the unexpurgated version of the output from
the test suite and noticed that six tests were marked as unexpectedly
succeeding. In test parlance, these tests are called TODO tests, since
they show what there is to do. This state of affairs is usually due to
a test case that is expected to fail when run, since it exercised a
bug in perl that needed to be fixed, and at some point, a source code
change caused the failing test to succeed.
Nicholas saw that many of the really old regexp bugs that have been
fixed, had no TODO tests, and in any event, the default, summarised,
output of the test test suite makes no mention of them anyway, so it
is not as if anyone would have noticed the improvement.
So firstly, the test harness had to be upgraded to report the summary
of TODO tests that succeed, and (much more work) all the open bugs
need test cases written for them, so that it becomes easier to see
when they have been fixed.
Yves Orton hacked up his copy of "Test::Harness" to do this. Andy
Lester took the idea and applied it to his development version of
"Test::Harness" (see the "New Modules" section below).
Abe Timmerman updated the test smoke kit, in order to get all this new
goodness into the hands of the smokers.
Much ado about todo
http://xrl.us/k2yg
Up in smoke
rsync -avz source.test-smoke.org::ts-current .
Coverity coverage of CPAN modules
After having read the traffic on p5p concerning the errors that
Coverity uncovered, Alan Olsen what the possibilities were for having
the tests extended to cover CPAN modules with XS components.
Johnathon Stowe realised that it was the output of "xsubpp" that needs
to be tested, rather than the ".xs" files themselves, and wondered
whether all the possible constructs it is possible to have "xsubpp"
emit ere in fact being covered, and whether one ought to create a
dummy XS module that simply causes "xsubpp" to emit everything it
knows how to.
Tim Jenness thought that that issue should be covered by
"XS::Typemap". Johnathon did some quick coverage calculations and was
surprised to learn that it wasn't too shabby.
Andy Lester volunteered to liaise with the Coverity people to have
XS-based modules analysed, should the authors in question care to know
the results. Randy W. Sims was concerned that some authors might think
of it as a ratings system. Be that as it may, a couple of authors
asked for analysis to be applied to their modules.
http://xrl.us/k2yh
Patches of Interest
This week, Andy Lester performed some more "op_type" shrinking in sv.c
and dump.c,
http://xrl.us/k2yi
and hauled some variables down into tighter scopes in util.c.
http://xrl.us/k2yj
212 warnings emitted by gcc-4.2
Marcus Holland-Moritz grew tired of watching an endless list of
warnings spew from compiling perl with a recent copy of "gcc", so he
patched things to get rid of the problems that gave rise to them.
Andy Lester was pleased to hear of the work, since it had been
something of an annoyance for him too. He asked for a slightly less
monolithic patch, so that different classes of errors could be fixed a
bit at a time. Rafael eventually applied all the changes.
Understanding error messages
http://xrl.us/k2yk
Watching the smoke signals
Nicholas Clark looked at a NetBSD smoke report, and wondered what it
was that was being tested in ext/B/t/bytecode.t that was failing.
Whatever it was, he fixed it with change #27874.
Smoke [5.9.4] 27855 FAIL(F) netbsd 3.0 (i386/1 cpu)
http://xrl.us/k2ym
Steve Peters wondered why a test run was failing, simply because TEST
was seeing test results being delivered out of order, where as harness
didn't care.
Smoke [5.9.4] 27939 FAIL(F) MSWin32 WinXP/.Net SP2 (x86/2 cpu)
http://xrl.us/k2yn
New and old bugs from RT
op/cmp.t and lib/bigfltpm failures (#5708)
Steve Peters and Johnathon Stowe kicked this bug around, but as
neither of them have access to the platform in question it shall have
to remain open for the time being.
OpenServer anyone?
http://xrl.us/k2yo
Regex replace loses characters (#24704)
Rafael fixed this bug by accident while working on something else.
No-one minded.
http://xrl.us/k2yp
In fact, Steve Peters continued his thankless task of trawling through
old, open tickets and noticed that a certain number of bugs had been
solved by changes committed recently and not so recently.
Fixed in previous millenium
http://xrl.us/k2yq
"Sys::Syslog)" requires \0 terminator in syslog messages (#28019)
Julian Mehnle called in from Debian-land to see what the status on
this bug was, explaining that some comments or documentation would
help avoid bugs being filed in the future.
http://xrl.us/k2yr
"threads" and "require IO" causes segmentation fault (#37076)
Nicholas Clark jotted down a couple of notes on how to fix this
problem.
Add it to the TODO
http://xrl.us/k2ys
Oxymoronic example in perlvar (#38743)
Steve Peters wondered why Dave's excellent example shouldn't be used
to close this ticket.
http://xrl.us/k2yt
"Text::ParseWords" doesn't always handle backslashes correctly (#38904)
John Vromans argued that the following equivalency was incorrect:
is_deeply([shellwords("aa bb cc\\ ")], ["aa", "bb", "cc "])
Alexey Toptygin delved into the code to find out why and offered a
patch to make the behaviour a little more intuitive. Applied by
Rafael.
http://xrl.us/k2yu
"map" sometimes uses only the last mapped value (#38935)
Someone on Perlmonks posted an innocuous question about some strange
behaviour with "map", that turned out to be a caused by a change that
was applied in 1998. People were surprised at that such a bug had
remained unnoticed for so long.
http://xrl.us/k2yv
The original thread
http://www.perlmonks.org/index.pl?node_id=543989
"Configure" won't handle versions 5.10.0 or 5.8.10. (#38945)
Andy Dougherty filed a bug on this problem so that people remember to
do something about it in time.
http://xrl.us/k2yw
Memory leak when calling "system 1 foo" repeatedly (#38946)
An interesting discussion arose from this report. It turns out that
"system 1, ..." does something interesting under Windows.
http://xrl.us/k2yx
Tests fail in 5.8.8 if $TMP is not writable (#38947)
Gabor Szabo noted that certain tests lib/Memoize/t/tie_ndbm.t fail if
the directory pointed to by $TMP was not writable. He felt that a
diagnostic should explain more clearly what the problem is rather than
failing out of hand.
http://xrl.us/k2yy
Migration Problem from Dynix to Aix (#38951)
Karuppiah Subramaniam has a migration problem. If you have any advice
to offer, I'm sure it will be appreciated.
http://xrl.us/k2yz
"exists" error message on wrong argument type is incorrect (#38955)
Jeremy Hetzler wished to clarify the error message received when
"exists" use incorrectly, and bring it into line with the
documentation.
http://xrl.us/k2y2
"File::Find" documentation - is "Don't modify these variables" still
valid? (#38965)
Steve Peters tweaked the documentation for "File::Find" to specify
more clearly what happens to $_ in the callback routine.
http://xrl.us/k2y3
Perl5 Bug Summary
9 created and 4 closed = 1543
http://xrl.us/kw9y
Steady as she goes
http://rt.perl.org/rt3/NoAuth/perl5/Overview.html
New Core Modules
* Test-Harness version 2.57_06, by Andy Lester. This enhances
the summary result to indicate clearly the number of TODO test
that have unexpectedly begun to succeed, (usually due to
underlying bugs being fixed).
http://xrl.us/k2y4
In Brief
Nicholas Clark carried out his threat to document code references in
@INC and source filters and also added a new feature at the same time.
http://xrl.us/k2y5
Paul Johnson read about the "is_list_assignment" speedup patch from
Andy Lester, and pointed the porters to a two year old thread on a
similar issue.
http://xrl.us/k2y6
Nick Ing-Simmons followed up on the issue of leaking file handles in
XS code.
http://xrl.us/k2y7
Jan Dubois removed some cruft from makedef.pl
http://xrl.us/k2y8
Jarkko Hietaniemi tried a patch to regcomp.c to see if it would
silence an error from Coverity. It didn't. This led Jarkko to conclude
that if Coverity was too clever, or too stupid, to figure out what was
really happening, then maybe it's Red-flag-for-Refactoring time.
It would help us, frail humans
http://xrl.us/k2y9
He then nailed another leak that Coverity found in doop.c.
http://xrl.us/k2za
Nicholas Clark saw that Coverity dislikes "PerlIO_findFILE". The logic
seems a bit tortuous, so maybe that's not so surprising,
http://xrl.us/k2zb
Nicholas looked at the last two unreviewed Coverity issues, in
regexec.c and wondered whether Coverity was getting confused. Dave
Mitchell explained that both issues were false positives.
http://xrl.us/k2zc
Alex Waugh provided the required information to support compiling perl
on RISC OS.
http://xrl.us/k2zd
Andy Lester posted a short script to prune Jarkko's "cpd" output, to
show more clearly where Cut-And-Paste code was happening in areas that
interested him.
http://xrl.us/k2ze
Yitzchak Scott-Thoennes fixed building perl on "Cygwin".
http://xrl.us/k2zf
Joshua Juran uploaded an experimental release of Lamp on SourceForge.
Lamp Ain't Mac POSIX
http://xrl.us/k2zg
Andy Lester refactored the excessive use of "PM_GETRE()" in pp_ctl.c.
http://xrl.us/k2zh
Jan Dubois and Steve Hay coordinated the ActiveState changes to
win32/Makefile in "blead", clearing up an issue concerning 64-bit
environments at the same time
http://xrl.us/k2zi
Nicholas Clark explained what he understood Larry's MAD patch to be
doing.
http://xrl.us/k2zj
The UTF-8 caching code that Nicholas Clark worked on a few months back
wound up being exposed on the command-line via the "-Ca" switch.
Unless someone has a better idea
http://xrl.us/k2zk
Nicholas Clark unearthed what is in hindsight a blindingly obvious
memory leak on unthreaded builds between "Perl_newCONSTSUB" and
"cv_undef".
Nobody else knew what to do about it, either.
http://xrl.us/k2zm
Andy Lester thought that "GvUNIQUE()" and its ilk could be removed
from the source. Rafael commented that the macros had to remain, since
at least "Data::Alias" on CPAN refer to them.
http://xrl.us/k2zn
Ashish Agarwal was having problems with weird characters displayed in
the debugger. Joe McGuire thought it was probably one of the thirteen
so-called variant characters in EBCDIC.
\ [ ] { } ^ ~ ! # | $ @ `
http://xrl.us/k2zo
Andy Lester cleaned up regexec.c following on from the recent changes.
http://xrl.us/k2zp
Rick Delaney had discovered that fields.pm lost their compile-time
benefit, dating back to when pseudo-hashes were removed from "blead".
http://xrl.us/k2zq
Ken Williams asked for advice on some proposed "File::Spec" changes
for VMS, John E. Malmberg supplied what information he could. Ken
lamented how difficult it was to test VMS code if you didn't have
access to a VMS box.
http://xrl.us/k2zr
Joshua ben Jore thought that the terribly cryptic
"select((select(OUTPUT_HANDLE), $| = 1)[0])" idiom should be banished
from the documentation. Rafael bowed to reason.
Just because you can
http://xrl.us/k2zs
The previous summary
The cynics scoffed at the effort expended to clear the Coverity
issues, and Rafael pointed out that "state" variables are almost but
not quite yet in "blead".
http://xrl.us/k2zt
About this summary
This summary was written by David Landgren.
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