This was a nice week, with lots of discussion, on various interesting topics. Read on for strange bugs, strange fixes, strange error messages, and as always, the ongoing efforts made to improve Perl 5.
our(%hash) The construct our(%hash) appears to be a lot slower than our %hash,
written without the parens (this is strange bug #17376). Yitzchak
Scott-Thoennes diagnosed the cause of this -- the parens trigger list
context, for no apparent purpose, hence the slowdown for large hashes --,
and he proposed new tests for it, with the appropriate failing tests
marked as TODO.
Dave Mitchell proposed a huge patch to move all code related to the handling of pads in new files, pod.h and pod.c. In addition to making the code clearer, better organized, and more maintainable, Dave also made the -DX debugging flag more comprehensive, and spotted a few places where improvements could be made. This kind of reengineering effort is rare enough to deserve to be underlined. The huge patch.
Marc Lehmann discovered that when you declare a package as
package test::
then the __PACKAGE__ token contains "test::" instead of
"test". Mike
Guy says that this behavior is to be expected, and gives some examples.
Arthur Bergman was puzzled by this warning : this one-liner
perl -we "close(STDOUT); open(F, qq{out.txt}) || die;"
says Filehandle STDOUT opened only for input (where out.txt is an existing file.) In fact, once STDOUT has been closed, F gets the file descriptor number of STDOUT. Hugo proposed to make the warning message more explicit, like Filehandle STDOUT reopened as F only for input.
Elizabeth Mattijsen warns : In order to determine ways of reducing
memory usage with perl, and with threaded perl in particular, I will be
annoying p5p with some memory benchmarks in the coming time. She adds
also that every related message she'll send to p5p will have [Memory]
in the subject line.
She started immediately to post a memory-related
message, wondering why
the threads module overloads the == operator. A long thread was the
consequence of this first post, where we learned why a specific comparison
method is needed (in fact, the == operator on threads compares thread
ids to know whether two threads objects refer to the same thread.)
charnames more flexibleH.Merijn Brand proposed to extend the charnames pragma to allow
user-defined aliases for commonly used Unicode characters. Jarkko
discussed some implementation and API issues with the proposed
implementation. Everybody seems to agree now, but there is apparently no
definitive patch in.
Eric Roode proposed to allow the I/O tuning variables ($,, $/, $\, $: and $^L) to be set on a per-filehandle basis. Hugo provided insightful advice about the proposed implementation and the potential problems.
Ton Hospel reported an obscure regexp behavior, bug #17542. At least perl golf is useful to uncover obscure bugs, isn't it ?
While we're at regexps, Barrie Slaymaker made the regexp engine dump core via recursion, matching a quite long string (bug #17611).
And also, bug #17605 is about a change of behavior between perl 5.6.x and 5.8.0 in the s///e operator, when the right side (the Perl expression) is empty. Nobody commented.
Sudhindra Herle proposed to add to Pod::Html the ability to translate links of form L<description|URL>. However Ronald J Kimball pointed out that this syntax is not valid POD, according to the specs.
Marcel Grünauer (author of Getopt::Attribute, this very cool module you
should try) found a bug (#17587) in Attribute::Handlers, that wasn't
recognizing shared and unique as built-in attributes. Rafael
Garcia-Suarez provided a patch (will hopefully will end up on CPAN).
Jarkko Hietaniemi provided a new manpage, perl573delta, missing from perl 5.8.0.
Andreas J. Koenig posted a documentation patch to the perlunicode manpage, providing a bit of good advice about porting code from perl 5.6.x. A code example included in the patch quickly triggered a discussion about the relative merits and readability of several perl constructs. The original intent of the patch was lost somewhere in the middle.
G. Rossati reported bug #17632, about stat() not behaving properly; it
turned out to be caused by File::stat, overriding the core function
stat(), but inconsistently (not checking for list context.) Hugo thinks
it's too late to change it to avoid difficult-to-spot breakages.
This summary brought to you, as usual, by Rafael Garcia-Suarez. It's also available via a mailing list, which subscription address is perl5-summary-subscribe@perl.org . As usual, comments, corrections and additions welcome. (Last minute -- for some reason Google sometimes doesn't seem to return the whole thread. So I link sometimes to another archive.)
Re:pod.[ch]?
rafael on 2002-10-01T06:59:33
Yes, obviously. And pads are (shortly) explained in perlguts.