This week on perl5-porters (22-28 July 2002)

This week on perl5-porters (22-28 July 2002)
     Unsurprisingly, this was one of the quietest weeks since I subscribed to
     P5P. Perl 5.8.0 has just been released, and the Perl 5.9 development
     track has yet to begin. So the bulk of the discussion was about small
     bugs and adjustments. Here's my subjective and arbitrary selection.

   New regexp metacharacters
     Jeff "japhy" Pinyan proposed a new regex pseudo-anchor, "\K" (which
     stands for *Keep*) that *basically fools the engine into thinking it
     just started matching.* In other words, "/pat1\Kpat2/" acts as a kind of
     look-behind assertion "/(?<=pat1)pat2/" (the only difference being when
     a "/g" modifier is used. Check the actual thread for the details.) Also,
     the pattern that precedes "\K" doesn't need to be constant-width, unlike
     what is currently required for look-behind assertions.

     The way this pseudo-anchor is implemented makes it quite efficient.
     Japhy gives another example of its usefulness :

         $str =~ s/(.*)\..*/$1/;

     can be written, using "\K", as :

         $str =~ s/.*\K\..*//;

     Brent Dax (who submitted last week a patch to, hm, forward-port a Perl 6
     construct in Perl 5) remarked that Japhy should mention this idea to
     Larry. Obviously we don't want Perl 5 and Perl 6 to diverge.

     Japhy also provided the corresponding "\F" pseudo-anchor that tells the
     regex engine it has stopped matching -- this one being equivalent to a
     look-ahead assertion. About this one, he says *I'm not 100% sure we need
     \F*, and also *I'm sure there's a need for \F, but I haven't quite
     figured it out yet.*

     The idea :
     http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-07/msg01324.html

     The patch :
     http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-07/msg01380.html

   A PerlIO / binmode() bug
     Elizabeth Mattijsen, who continues to experiment with "PerlIO::via",
     found that "binmode()" passes incorrect mode and handle parameters to
     "PerlIO::via::PUSHED()" when it's used to push a new PerlIO layer on an
     existing filehandle. Nick Ing-Simmons corrected this bug.

     Bug #15283 :
     http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-07/msg01294.html

   Trailing slash problem
     Abigail reported that some tests fail during perl's build when a
     Configure option of "-Dprefix=/some/dir/" (with a trailing slash) was
     used. This is a known problem, but those who haven't dug through the
     INSTALL instructions may loose some time to find out the cause. H.
     Merijn Brand provided a patch to correct the problem.

     Bug #15326 :
     http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-07/msg01311.html

   Crypt::SSLeay build problems
     Randy J. Ray reported that he couldn't build the "Crypt::SSLeay" module
     with perl 5.8.0. This problem does not appear with recent openssl
     libraries ; it can also be solved by forcing the C preprocessor symbol
     "PERL5" to be defined in "Crypt::SSLeay"'s Makefile.PL. However the
     precise cause of this problem is still not known.

     Randy also reported a problem on building Gtk-Perl, but nobody replied.

     http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-07/msg01346.html

   No non-perlio smoke tests anymore
     H. Merijn Brand, eminent smoke tester (on AIX, HP-UX and Cygwin
     platforms), decided to remove the non-perlio configurations from his
     tests.

   Memory benchmarks on threads
     Elizabeth Mattijsen decided to run some benchmarks on memory usage of
     threaded programs; in particular, the memory usage of "our", "my" and
     global variables, without attributes or with ":unique" or ":shared". I
     won't summarize her results here, please refer to the relevant threads
     for the details.

     Some threaded memory benchmarks :
     http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-07/msg01422.html

     More memory benchmarks
     http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-07/msg01438.html

     More memory/processing benchmarks
     http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-07/msg01467.html

   qq(\Q\E)
     Philip Hazel noticed that perl refuses to parse empty escape sequences
     in double-quoted strings, such as "\Q\E", "\u\E", "\L\E", etc. Fixing
     this bug involves playing with some of the darkest magic you can find
     in the tokenizer. Nicholas Clark commented : *it's far too scary to work
     out what to do right now.*

     Bug #15549 :
     http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/2002-07/msg01502.html

   Finally
     This summary brought to you by Rafael Garcia-Suarez, enduring high
     summer temperatures. This report is also available via a mailing list,
     which subscription address is [email protected].