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This Week on perl5-porters (27 October / 2 November 2003)

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Rafael Garcia-Suarez
November 3, 2003 05:29
This Week on perl5-porters (27 October / 2 November 2003)
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This Week on perl5-porters (27 October / 2 November 2003)
  The big news of the week is of course the first release candidate of
  perl 5.8.2, the problems it solves, and the new problems it causes.

  Nicholas Clark, the new maint pumpking (if you have missed previous
  episodes), released perl 5.8.2-RC1.
      first perldelta draft :

  Alexey Tourbin found a problem with this latest version : an
  incompatibility is caused by a patch to committed at the
  beginning of the month. This affects BerkeleyDB's test suite, but can
  arguably be caused by BerkeleyDB's reliance on the specific behaviour so
  far of UNIVERSAL::import(), that was inherited by subclasses. Paul
  Marquess is going to fix the next release of BerkeleyDB. Nicholas backed
  the change out of maint for 5.8.2.

  Another compatibility problem was caused in mod_perl by a patch by Rick
  Delaney that changed the behaviour of require() regarding files that one
  try to load again after a first unsuccessful attempt. This one also was
  backed out of maint.

The adventures of binary compat
  There was also a long, technical discussion about mod_perl 2 and the new
  hashing scheme in perl 5.8.2 (rehash hashes only if a bucket contains
  too many entries), that was introduced for binary compatibility. These
  threads involved also security considerations and tests for potential
  attacks against this hashing schemes. I'll shamelessly refer the
  interested parties to the archives :

  Meanwhile, Jan Dubois spotted another potential binary incompatibility
  between 5.8.0 and 5.8.1, the problem being related to the reentrant
  APIs. His proposed change doesn't solve all issues (XS modules compiled
  with a threaded 5.8.1 and that use the reentrant system calls will have
  problems) but it makes the situation better, as it restores the
  compatibility between 5.8.0 and 5.8.2. Details to be supplied in the
  next iteration of perldelta.

Threads and -D
  Stas Bekman produces a segfault by using the -Dm debug flag on a
  threaded perl, and suggests a patch. Rafael says that spotting problems
  with perl's debugging flags could be done by running perl's test suite
  with "PERL5OPT=-D..." (at least for the tests that aren't run under
  taint mode).

Attribute::Handlers and UNIVERSAL
  Michael Jacob notices that Attribute::Handlers is a bit cavalier with
  UNIVERSAL, pushing itself into @UNIVERSAL::ISA. Thus, all classes now
  can() AUTOLOAD(), DESTROY() and import(). To fix this, he suggests to
  override UNIVERSAL::can() to reject inherited methods. But Damian Conway
  says he hasn't a good solution for this problem.

Setting group and user ids
  Alan Burlison remarks that assigning to $) and then to $> doesn't
  produce the same result than assigning to the list "($),$>)" (at least
  on Solaris.) Rick Delaney sends a patch, but points out that it's hard
  to write tests for this.

Selected bugs
  Abigail reported (bug #24313) that the numeric constant 0 can't be
  overloaded via overload::constant('integer') like other integers. This
  was fixed by Rick Delaney.

  Ton Hospel produces a segfault by attempting to modify an array slice
  with "-=" while the array is being assigned to. Michael Jacob explains
  why this happens, but there's no fix in sight. (bug #24342.)

  Ton Hospel also files bug #24346, about the substr() lvalues. He notices
  that he's able, when operating on a substring, to pull in characters
  from the rest of the said string (i.e. from outside the substr()
  window.) As the docs are unclear, he can't say he's sure it's a bug, but
  that's at least a potentially dangerous behaviour. Graham Barr proposes
  a patch.

  David Nicol has some problems with a snippet of code where he's
  eval()'ing a string that contains a scalar variable in an END block (bug
  #24296). Dave Mitchell explains what's happening and provides some
  insight about how closures work.

  Yitzchak Scott-Thoennes demonstrates that list assignment to a hash in
  list context has some problems (bug #24380).

In Brief
  Arthur Bergman considers deprecating the SvPVX macro.

  Jeff Pinyan has a question about how the regular expression engine
  treats terms that match an empty string in an alternation. Mark-Jason
  Dominus provides some answers.

  ExtUtils::MakeMaker 6.18 is coming soon, announces Michael Schwern,
  listing the new improvements and features :

  Nicholas explicits his maint patching policy.

About this summary
  This week was summarized by Rafael Garcia-Suarez. Summaries appear
  weekly on and on a mailing list, which subscription
  address is Corrections and comments
  are welcome.

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