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From s...@apache.org
Subject cvs commit: modperl-docs/src/docs/1.0/guide porting.pod
Date Tue, 15 Jul 2003 11:06:02 GMT
stas        2003/07/15 04:06:02

  Modified:    src/docs/1.0/guide porting.pod
  Log:
  document the issue with persistant hash iterator
  
  Revision  Changes    Path
  1.19      +31 -1     modperl-docs/src/docs/1.0/guide/porting.pod
  
  Index: porting.pod
  ===================================================================
  RCS file: /home/cvs/modperl-docs/src/docs/1.0/guide/porting.pod,v
  retrieving revision 1.18
  retrieving revision 1.19
  diff -u -r1.18 -r1.19
  --- porting.pod	7 Mar 2003 04:29:59 -0000	1.18
  +++ porting.pod	15 Jul 2003 11:06:02 -0000	1.19
  @@ -2250,7 +2250,37 @@
   
   You should be especially careful with L<Perl Special
   Variables|general::perl_reference::perl_reference/The_Scope_of_the_Special_Perl_Variables>
which cannot be
  -lexically scoped.  You have to use local() instead.
  +lexically scoped.  You have to use C<local()> instead.
  +
  +Here is an example with Perl hash variables, which store the iteration
  +state in the hash variable and that state persists between requests
  +unless explicitly reset. Consider the following registry script:
  +
  +  #file:hash_iteration.pl
  +  #----------------------
  +  our %hash;
  +  %hash = map {$_ => 1 } 'a'..'c' unless %hash;
  +  
  +  print "Content-type: text/plain\n\n";
  +  
  +  for (my ($k, $v) = each %hash) {
  +      print "$k $v\n";
  +      last;
  +  }
  +
  +That script prints different values on the first 3 invocations and
  +prints nothing on the 4th, and then repeats the loop. (when you run
  +with httpd -X). There are 3 hash key/value pairs in the global
  +variable C<%hash>.
  +
  +In order to get the iteration state to its initial state at the
  +beginning of each request, you need to reset the iterator as explained
  +in the manpage for the C<each()> operator. So adding:
  +
  +  keys %hash;
  +
  +before using C<%hash> solves the problem for the current example.
  +
   
   =head1 Generating correct HTTP Headers
   
  
  
  

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