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  1. #!/usr/bin/perl
  2. # Idiom #282 Use a custom type as map key
  3. # https://p...content-available-to-author-only...s.org/idiom/282/use-a-custom-type-as-map-key/6042/perl
  4.  
  5. use v5.10;
  6. use Data::Dumper;
  7.  
  8. package Foo {
  9.    use Scalar::Util 'refaddr';
  10.  
  11.    use overload '""' => sub { shift->_stringify() };
  12.  
  13.     sub _stringify {
  14.         my $self = shift;
  15.         my $x = $self->x;
  16.         return "object $x: " . refaddr $self;
  17.     }
  18.     sub x { my $self = shift; $self->{x} // '' };
  19.  
  20.     sub new { my $class = shift; return bless { @_ }, $class }    
  21. };
  22.  
  23. my $p = Foo->new(x => 5);
  24. say '$p->x is ', $p->x;
  25.  
  26. my %map;
  27.  
  28. $map{$p} = 'some data';
  29.  
  30. say Dumper \%map;
  31.  
Success #stdin #stdout 0.02s 6996KB
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$p->x is 5
$VAR1 = {
          'object 5: 94063102878328' => 'some data'
        };
https://ideone.com/bRb55i
Idiom #282 Use a custom type as map key
language:
Perl (perl 5.28.1)
created:
2 years ago
visibility:
public

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