This Week on perl5-porters (20-26 January 2003)
This week, the P5P summary will attempt to entertain you with several
low-level hacks. (A weird kind of entertainment if any.) Read about
printf(), optimisations, internals, perldoc, and other code stories
below.
printf, perlio and XS
Nick Ing-Simmons changed (or restored, depending on the point of view)
the meaning of printf() in XS code. As of Perl 5.8.0, printf() was
#define'd to be an alias to "PerlIO_printf(PerlIO_stdout(),...)". Now,
it will be the bare C-level stdio printf(). Notably, when the standard
output is redirected from a Perl program, and when the perlio layer is
used (e.g. when the PERLIO environment variable has the value "perlio"),
printf() will continue to write to the pristine stdout stream. Thus,
it's now possible to have access to the perlio and to the stdio
implementations from XS.
This eventually caused some smoke tests to fail.
http:[EMAIL PROTECTED]/msg91091.html
Modify a subroutine's prototype
Mark-Jason Dominus wants a way to modify, at run-time, the prototype of
a subroutine, and explained why (bug #20463). Rafael Garcia-Suarez said
that this doesn't need to be in the core, and proposed a naive
Inline::C-based implementation. However, as MJ wants this feature for
Memoize, which is a core module, it needs to be in the core : perhaps in
the Scalar::Util module ?
http:[EMAIL PROTECTED]/msg91171.html
,=
Joachim Breitner, wondering how to merge hashes efficiently, proposed to
introduce a new operator, ",=", so that
%hash1 ,= %hash2;
would be semantically equivalent to
%hash1 = (%hash1, %hash2);
but faster (and it would work similary for arrays). Mark-Jason Dominus
pointed out that push() already merges arrays, and that "some time ago
there was discussion of extending push to operate on hashes also".
Nicholas Clark objected to this new operator, as efficient merging of
hashes can be done in a XS module ; and he provided this XS module,
Hash::Append. (Though perhaps this code belongs to the core module
Hash::Util.) Abigail, on the other hand, approved the creation of a
new operator, but dislikes the odd-looking ",=".
http:[EMAIL PROTECTED]/msg91184.html
In brief
Dave Mitchell fixed the debugger slowdown noticed last week.
Mark Mielke noticed that "the array of back-references attached to a
reference never shrinks", and he proposed a patch to improve the speed
of the routine that weakens references.
http:[EMAIL PROTECTED]/msg91077.html
There was a thread about the different ways to modify the "fileno" value
of a FILE C structure on various platforms.
http:[EMAIL PROTECTED]/msg91095.html
Dan Kogai released Encode v1.85, and, a few hours later, v1.86. Note
that some tests are skipped on perl 5.8.0, since they rely on newest
fixes.
http:[EMAIL PROTECTED]/msg91144.html
Rafael Garcia-Suarez sent a fix for bug #18232 : the $1...$n variables
loose their utf8 flag when they're overriden by another pattern match in
an enclosed scope.
David Nicol reports (bug #20503) that perldoc produces confused output
on RedHat 8.0. Guess what, that's probably caused by UTF8 locales. Russ
Allbery blames groff. Adrian Enache suggests to pass the option
-Tlatin1 to [ng]roff (and to change /etc/man.config as well).
Adrian Enache also reports that reading from a filehandle in
fixed-length record mode, and appending the results to a variable,
doesn't work correctly since Perl 5.7.2. He also fixed it.
Alain Barbet posted some graphs about the smoke test results.
http://www.alianwebserver.com/perl/smoke/stats.html
Sean M. Burke advices Windows users to upgrade their perldoc to the
newest distribution (Pod::Perldoc) he put up on CPAN. The original
perldoc distributed with 5.8.0 apparently has problems with some pagers
(e.g. "more" on some flavours of Windows.)
About this summary
This summary brought to you by Rafael Garcia-Suarez. Summaries are
available on http://use.perl.org/ and/or via a mailing list, which
subscription address is [EMAIL PROTECTED] Comments and
corrections are welcome.
