use Perl

• Odd - Pug's state worked correctly back in 2005 (Score:1)

  by Limbic Region (3985) on 2008.04.29 8:15 (#62464) Homepage Journal

  See http://svn.pugscode.org/pugs/examples/cashiers.pl [pugscode.org]

  # Demo of the state() variable declaration.
  # This is also a neat way of doing OO without actually having OO available.
  #
  # Please remember to update t/examples/examples.t and rename
  # examples/output/cashiers if you rename/move this file.
   
  use v6-alpha;
   
  sub gen_cashier () {
      # This variable corresponds to a class variable.
      # It is shared across all "instances" of gen_cashier().
      state $cash_in_store = 0;
   
      # One could add my() variables here, which correspond to instance variables.
      # These would not be shared.
   
      # Finally, we return a hashref which maps method names to code.
      return {
          add => { $cash_in_store += $^amount },
          del => { $cash_in_store -= $^amount },
          bal => { $cash_in_store             },
      };
  }
   
  my $drawer;
  $drawer[$_] = gen_cashier() for 1..3;
   
  $drawer[1]<add>( 59 );
  $drawer[2]<del>( 17 );
  say $drawer[3]<bal>();  # This should say "42"

  It was written back in July of 2005 before pugs had OO.
  
  I don't have pugs installed at work to test and I can't remember the right fu to get the evalbot in #perl6 to test for me

  Reply to This

  • Re: (Score:2)

    by nicholas (3034)

    I don't think that it did. Certainly, that example is not a good enough test, because it makes all three calls to gen_cashier before it uses any of the closures, so it makes no difference how many times that assignment of 0 is performed. If I re-write it like this

    use v6-alpha;
    
    sub gen_cashier () {
        # This variable corresponds to a class variable.
        # It is shared across all "instances" of gen_cashier().
        state $cash_in_store = 0;
    
        # One could add my() variab