use Perl

• Re: (Score:1)

  by Aristotle (5147)

  So it can serialize closures without losing information?
  • Re: (Score:1)

    by demerphq (2831)

    Yep. Eg:
    
    D:\Development>perl -MDDS -e"my $closure=do{ my $x=100; sub { $x++ } }; Dump $closure"
    
    my ($x);
    $x = 100;
    $CODE1 = sub {
                          $x++;
                      };
    • I can break this... (Score:1)

      by btilly (5037) on 2005.05.25 20:04 (#40726) Journal

      The following code crashes.

      #! /usr/bin/perl
      use strict;
      use Data::Dump::Streamer;
      
      Dump [
        map {
          my $x;
          my $x_eclipse_1;
          sub {$x}, sub {$x_eclipse_1};
        } 1, 2
      ];

      I thought about trying to solve this with intelligent mangling, but there is always a boundary case. For instance if you mangle anything with $x_eclipse_1 in some way (eg make it $x__eclipse_1), what if there is a global variable $x_eclipse_1? Now you've changed semantics or else get a crash.

      After some thinking, the only strategy that looks like it would work perfectly is to go to a nested data structure in the event of collisions. You could do that like this. Suppose that you had multiple closures pointed at $foo. Then make $foo an anonymous array of scalars and make the closures each point at $foo->[$i] where $i is an index. In the case of @foo you can make it @{$foo[$i]} instead. In the case of %foo you can make it %{$foo{$i}}. In each case the eclipsing is done without accessing any other variable name that might also be accessed.

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      • Re:I can break this... (Score:1)

        by demerphq (2831)

        The following code crashes.

        Shoot. Yep. It does. And it highlights what I forgot to document: the subs being dumped shouldn't mix the use of dynamics and lexicals with the same name, and that its is unwise to use variables matching /_eclipse_\d+$/. (Which personally I think is not such a terrible restriction, albeit not at all ideal.)

        Dealing with the former is actually very tricky, and probably wont ever be solved properly. A good example is

        my $a=sub { $a++ };

        The second issue regarding eclipsed