This Week on perl5-porters - 24-29 February 2008

This Week on perl5-porters - 24-29 February 2008

   "Is this a bug? Or why is this the expected behaviour?" -- Steffen
   Ullrich, playing with signal handlers.

Topics of Interest

"use encoding 'utf8'" bug for Latin-1 range

   The thread about "use encoding" continued this week. Juerd Waalboer
   gave one of the best concise explanations as to why the current model
   Perl uses for dealing with Unicode is broken, which is that the "\x"
   hex escape is overloaded for bytes ("\x2b" *versus* "\x{d0b2}"), and
   that it takes place too early, while the source is being read.

   The result of which is that a source code file encoded in an Asian
   language cannot embed a latin-1 character like an e-acute.

   Much discussion of remarkable civility followed, regarding what to do
   about the matter. Glenn Lindemann put forward the following ideas:

   *   Deprecate "use encoding".

   *   Deprecate non-ASCII characters in 5.12 source code, unless a
       source encoding has been specified.

   *   Allow Unicode semantics to be applied to all character operations
       on strings (case conversion, caseless comparisons and so on),
       regardless of their internal representations.

   *   Sort out the timing of when "\x", "\x{}" and "\N" take effect.

   No-one appeared to lament the idea of letting "encoding" go.

   Yves Orton pointed out that Microsoft managed to get their Unicode
   handling more or less right, albeit at a certain cost to their API,
   and regretted that Unix-like operating systems supplied the absolute
   strict minimum, pushing all the work onto each and every client
   program. Which meant that nothing really worked at all, not even the
   so-called shebang line.

   Juerd and Nicholas put forward that there is a case to be made for
   perl to figure out itself whether a given source file is in ASCII,
   Latin-1 or UTF-8. It turns out that it's just about impossible to
   construct a sensible Latin-1 file that also turns out to be be valid
   UTF-8. The idea is to start out in 7-bit ASCII and carry on until a
   byte with the high bit set is encountered.

   If this byte introduces a valid UTF-8 character, the rest of the file
   must be, too. Any invalid byte sequences thereafter trigger a fatal
   compile-time error. Otherwise it means it must be Latin-1, in which
   case similar but different rules apply which also cause the
   compilation to halt if encodings change mid-stream. The key issue is
   to determine that the encoding does indeed change.

   EBCDIC was also mentioned in passing. Sadly, Perl no longer runs on
   EBCDIC due to a general lack of nurturing. Then again, if it was
   important, Nicholas felt that someone from IBM would have been in
   touch at some point.

     for some reason I now have a splitting headache
     http://xrl.us/bg932

Interrupting "system()" with signal depends on signal handler

   Steffen Ullrich noticed that an "alarm" signal handler that does a
   "syswrite" as opposed to a "print" behave differently. After diving in
   through pp_sys.c, he noticed that he could make the "print" version
   (which was working correctly) behave the same incorrect way, by
   setting $! to undef.

   He produced a one-line patch that fixed the behaviour (hmm, did we get
   a test?) and Rafael applied it as change #33408.

     handle with care
     http://xrl.us/bg98g

CPAN NetBIOS broadcasts

   Linda W was scratching her head wondering why CPAN installations on
   cygwin were glacially slow. After running a network trace, she
   discovered that what had been a path /var/cache/cpan was being
   interpreted as a UNC path (/cache/cpan on host //var).

   This caused the local host to send out plaintive calls for host //var
   to please call home. Michael G. Schwern thought that this sounded like
   the same problem described in CPAN bug #32813, as did Linda.

   Yves Orton, current maintainer of "ExtUtils::Install", which is were
   the problem originated, pushed out a new version and Linda confirmed
   that it solved the problem.

   Ken Williams was not around to comment on how hard it is to use
   File::Spec correctly.

     not quite Unix, not quite Windows
     http://xrl.us/bg934

Google summer of code

   Eric Wilhelm got the ball rolling on Perl's participation in Google's
   Summer of Code project. But you've probably heard about this in other
   venues. All hail Eric.

   The Perl 5 Wiki is place to go for the latest information.

     summertime fun
     http://xrl.us/bg936
     http://xrl.us/bg938

Patches of Interest

sv.c consting goodness

   Steven Schubiger's consting patch number 4 from the beginning of the
   month was applied. This lead to patches 5, 6, 7, 8 and 9, all applying
   ever more consting to sv.c being issued by Steven, which in turn were
   all applied by various porters.

     http://xrl.us/bg94a

no archlib in otherlibdirs

   After some long, hard thought, Andy Dougherty remembered why Reini
   Urban's plan for organising site and vendor libraries on Cygwin
   wouldn't work in the general case. So Reini withdrew his patch but
   would continue to use it locally.

     http://xrl.us/bg94c

   On the other hand, his enhancements to "B::Debug" made it in.

     win some, lose some
     http://xrl.us/bg94e

warning message for -M:Foo, extended and revised

   Robin Barker finally settled on "Invalid module name :Foo with -M
   option: contains single ':'", which was good enough for Rafael

     colonphun
     http://xrl.us/bg94g

More diagnostics for Fatal.pm

   Slaven Rezic enhanced "Fatal" to name the builtin that could not be
   overridden in its dying message.

     if I told you I would have to kill you
     http://xrl.us/bg94i

Thread patches

   Jerry D. Hedden is doing so much work on threads at the moment, he
   deserves his own section.

   First off, the patch to not install threads on non-thread builds was
   reverted (Michael G. Schwern killer argument being that at least that
   way you get a nice error message).

     http://xrl.us/bg94k

   Then the CPAN 1.69 version of "threads" was synch'ed with blead.

     http://xrl.us/bg94n

   As was "threads::shared" 1.17.

     http://xrl.us/bg94p

   At the end of the week, he also delivered version 1.18, which added
   some diagnostics to help track down what's going wrong when t/stress.t
   decides to go belly up.

     http://xrl.us/bg94r

   Moving along, "Thread::Semaphore" 2.07 checked in.

     http://xrl.us/bg94t

   and last but not least, "Thread::Queue" 2.06 did too.

     http://xrl.us/bg94v

Watching the smoke signals

   It looked like t/stress.t in the threads module failed, and so Jerry
   asked if there was any chance of seeing what the new diagnostics had
   to say. Steve Hay discovered that the problem was in fact a TODO test
   that had started to pass, and Test::Smoke got confused and recorded it
   as a failure.

     Smoke [5.11.0] 33390 FAIL(F) MSWin32 WinXP/.Net SP2 (x86/2 cpu)
     http://xrl.us/bg94x

New and old bugs from RT

Segfault when calling "->next::method" on non-existing package (#51092)

   David Landgren thought that the test that Rafael Garcia-Suarez added
   as part of the fix for this bug should have had the RT bug number
   embedded in it somewhere. In other other news, we discovered that
   there are 485 subscribers to perl5-porters.

     http://xrl.us/bg94z

Perl5 Bug Summary

     288 new + 1500 open = 1788 (+3 -2)
     http://xrl.us/bg943
     http://rt.perl.org/rt3/NoAuth/perl5/Overview.html

New Core Modules

   ExtUtils::Install version 1.45
       This was the fix for the "//var" problem noted by Linda W. (But
       stay tuned next week for exciting new developments).

         http://xrl.us/bg945

   ExtUtils::MakeMaker 6.44
       Michael G. Schwern rolled out 6.34_01 plus Yves's EU::I 1.45 as
       version 6.44. Other assorted bugfixes made it in, but Michael
       announced that he had declined to put in the fixes required to
       make paths with whitespace work correctly, saying that he wanted
       to think about a better solution.

         http://xrl.us/bg947

In Brief

   Last week, Jim Cromie had the newfound ability to hook XML analysis to
   a test suite (via the "PERL_XMLDUMP" environment variable). This week,
   Jim wrote a patch to test -Dmad's PERL_XMLDUMP= output. It was not
   applied.

     truly madly
     http://xrl.us/bg949

   On the other hand, Rafael did apply his optimisation of the
   "OP_IS_(FILETEST|SOCKET)" macros, with some "OP *"/"int" fuzz.

     http://xrl.us/bg95b

   The exact recipe for signalling a non-met prerequisite (such that a
   perl build without threads should not attempt to require threads) was
   nailed down and codified on the CPAN Testers wiki.

     http://cpantest.grango.org/
     http://xrl.us/bg95d

   Salvador Fandiño found that the documentation made no mention of
   "av_delete" calling "sv_2mortal" on the returned "SV". Yet "av_pop"
   and "av_shift" don't and so the documentation should probably point
   out the difference.

     quirk quirk
     http://xrl.us/bg95f

   Craig Berry reported that maint-5.8 was not compiling on VMS, largely
   due to incorrect prototypes in re.xs. Nicholas Clark determined that a
   subsequent integration fixed the problem.

     a matter of time
     http://xrl.us/bg95h

   Steve Peters wanted to know why quad words on Win32 weren't
   configured, since all the pieces were in place to allow them to be.
   Jan Dubois thought that it wasn't much of a problem since you really
   need to have "IVSIZE" defined to be 8 to take any advantage of them.

     mmm, bignums
     http://xrl.us/bg95j

   Nicholas Clark hacked "perlbug" to allow it to send thank-you messages
   back to the porters.

     send more money
     http://xrl.us/bg95m

   Nicholas also got his languages mixed up trying to write else if in C
   macros. Fortunately there are only four or five distinct syntaxes to
   master for writing else if constructs in all computer languages.

     as if
     http://xrl.us/bg95o

About this summary

   This summary was written by David Landgren. I chopped a day off this
   week; it makes it easy to start next week on the first of the month.

     17-23 February 2008
     http://xrl.us/bg95q

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