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This week on perl5-porters (10 June--17 June 2001)

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From:
Simon Cozens
Date:
July 10, 2001 05:57
Subject:
This week on perl5-porters (10 June--17 June 2001)
Message ID:
20010710135720.A8534@deep-dark-truthful-mirror
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----------------------------------------------------------------

  This week on perl5-porters (10 June--17 June 2001)
  
     * Notes
     * No 5.8.0 Yet
     * New Modules
     * Numbers, numbers, numbers
     * PerlIO considered evil
     * Asynchronous Callbacks
     * Various

  Notes
  
   Please send corrections and additions to
   perl-thisweek-YYYYMM@simon-cozens.org where YYYYMM is the current year
   and month. Changes and additions to the perl5-porters biographies are
   particularly welcome.
   
   This was a reasonably busy week, seeing just over 400 messages. I say
   that every week, don't I?
   
  No 5.8.0 Yet
  
   [1]Jarkko sadly announced that 5.8.0 wasn't going to happen before the
   Perl Conference, but 5.7.2 is imminent:
   
     I think it's time for me to give up the fantasy that 5.8.0 will
     happen before the Perl Conference. The stars just refuse to align
     properly, too many loose ends, too many delays, too many annoying
     mysterious little problems, too little testing of CPAN modules.
     Luckily, nothing is majorly broken, and I think that I've more or
     less achieved what I set out to do with Perl, so I still hope to be
     able wrap something up before TPC and call it 5.7.2 (it must happen
     next week or it will not happen), and soon after the conference put
     out the Release Candidate 1 for 5.8.0, and then keep cracking the
     whip till we are happy with what we've got.
     
  New Modules
  
   These aren't really very new, but they may have slipped through the
   net and you haven't noticed them yet, and since they're interesting,
   you might want to have a look...
   
   I18N::LangTags detects and manipulates RFC3066 language tags;
   Locale::Maketext is extremely useful for localizing text; Unicode::UCD
   is a neat interface to the Unicode Character Database; Encode is
   coming on strong, and can now read IBM ICU character tables;
   Mark-Jason Dominus' Memoize module is now part of the core.
   
  Numbers, numbers, numbers
  
   Remember last week's weird Amdahl UTS bug, where [2]Nicholas Clark was
   convinced UTS C was doing a decrement statement twice? He found the
   problem - the decrement statement shouldn't have been there at all...
   
   This prompted him to find a bug in grok_number; this surprised me a
   little, because I didn't know that grok_number even existed. All of
   the useful, platform-independent code which deals with numeric
   operations - casting between different sizes, converting binary, hex,
   and octal numbers, recognising numbers in strings, and so on, has been
   moved to numeric.c. Take a look at it, there's a load of handy stuff
   in there.
   
   Hal Morris, our UTS wizard, also pointed out some unpleasant casting
   assumptions, which needed a patch:
   
     UV_MAX must NOT be defined as (unsigned long){whatever} for UTS,
     because then comparisons with double will not work correctly (there
     is no problem with (unsigned) typecasts, only with (unsigned long))
     
   grok_number again came in handy on QNX, when Norton Allen found that
   strtoul wasn't setting errno correctly on overflow. It's sad when we
   have to start reimplementing people's broken C libraries, but this is
   the price of portability.
   
  PerlIO considered evil
  
   [3]Ilya found a bug in PerlIO, then found another bug while attempting
   to demonstrate it. The original bug was:
   
     The *actual* problem is that char-by-char input requires DUPLICATE
     pressing of ENTER key for this key to be seen by Perl. Debugging
     this problem (via Term::ReadKey test suite) shows the following
     logic:
     
     pp_getc() calls is_eof() which does getc/ungetc calls getc()
     
     [BTW, I see no logic in this sequence of events.]
     
     The problem is that ungetc() can't unget "\n" if this \n is the
     first char in the buffer, and quietly drops "\n" to the floor.
     
   Ilya had a lot of invective set aside for PerlIO, which we need not go
   into. Needless to say, he did not provide an alternative
   implementation of a multi-layered standard IO system as a patch. Or
   indeed any patch at all.
   
   Vadim Konovalov did provide a simple patch to clean something up, but
   then [4]Andy and [5]Nick both showed that it didn't help at all, the
   generated code being the same and some compilers not being able to
   cope with lvalue casts, which Nick had carefully removed and Vadim's
   patch reintroduced. Guess Nick might actually know what he's doing
   after all.
   
  Asynchronous Callbacks
  
   David Lloyd asked how do safely do asynchronous callbacks from C to
   Perl. Bejamin Stuhl suggested hacking the core to introduce some
   checks during the inter-opcode PERL_ASYNC_CHECK, and suggested that
   Perl 5.8.x had a public way of registering inter-opcode callbacks.
   David Lloyd replied that PHP/Zend already had this, and you could even
   implement a signal checking add-on module without any core hacking.
   Paul Johnson went one further, and suggested using a pluggable runops
   routine. Surprisingly, this has actually been implemented but nobody
   really knows about it; Devel::Cover apparently makes use of it. Of
   course, the problem is that only one thing can use a custom op loop at
   a time, so David suggested writing an XS module that allowed other
   modules to add callbacks. I hope that happens.
   
   Artur Bergman popped up and, predictably, suggested using ithreads.
   
  Various
  
   Rudi Farkas found a weird one on Win32 - on that platform,
   executableness (the -x test) is determined by the filename being
   examined. For instance, foo.bat is classed as executable, but foo.bar
   is not, even if they contain exactly the same data. This rather
   curious design decision leads to the fact that if you call stat with a
   filename, the execute bit is set depending on the extension. If, on
   the other hand, you call fstat with a filehandle, Windows can't
   retrieve the filename and test the extension, so it silently sets the
   execute bit to zero, no matter what it gets fed. This is Bad, and
   means that -x _ on Windows is unpredictable. Radi provided a suggested
   workaround, but nobody cared enough about fixing something so
   obviously braindead to produce a patch.
   
   Mike Schwern fixed up MakeMaker to stop producing extraneous -I...s
   when building extensions, and also found that the XS version of Cwd
   won't do much good as a separate CPAN module, since it relies on the
   core function sv_getcwd, which only appears in 5.7.1. Oops. Oh, and
   speaking of Cwd, Ilya patched it up a bit for OS/2, while noting that
   its results were untainted on that platform.
   
   Ilya also fixed a glaring debugger bug (oh, the irony) prompting
   Jarkko to lament the lack of a test suite. Robin fixed up a couple of
   weird, weird bugs in B::Deparse.
   
   Jonathan Stowe upgraded pl2pm to be warnings and strict clean. I'm not
   sure why.
   
   Philip Newton patched a score of typos. Norton Allen updated the QNX
   documentation and provided a couple of other fixes.
   
   Piers Cawley found something that looked like a bug in SUPER:: but was
   assured that it wasn't; Randal won the day with a reference to
   Smalltalk.
   
   Abhijit Menon-Sen (look out for this guy...) made mkdir warn if it was
   given a non-octal literal, since that generally doesn't do what people
   want, and after prompting from Gisle, did the same for umask and
   chmod. Unfortunately, he forgot about constant folding...
   
   Until next week I remain, your humble and obedient servant,
     _________________________________________________________________
   
   [6]Simon Cozens

References

   1. http://simon-cozens.org/writings/whos-who.html#HIETANIEMI
   2. http://simon-cozens.org/writings/whos-who.html#CLARK
   3. http://simon-cozens.org/writings/whos-who.html#ZACHAREVICH
   4. http://simon-cozens.org/writings/whos-who.html#DOUGHERTY
   5. http://simon-cozens.org/writings/whos-who.html#ING-SIMMONS
   6. mailto:simon@brecon.co.uk

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