in reply to Effecient shortcut for ?:

Another approach to the ones above is to establish defaults when you set up the hash. This is common when creating objects. 
  sub new {
      my $pkg = shift;
      my $self = { a => $default_for_a, @_ };
      bless $self, $pkg;
  }

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If you don't specify a binding for "a" when you create the instance, you get the default. If do specify a binding, as with   my $foo = new Foo(a => 47); then the default is overlaid.

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Re^2: Effecient shortcut for ?:
by tadman (Prior) on Aug 07, 2002 at 18:49 UTC
    I do this occasionally, when establishing quick defaults. Testing revealed that the last defined key/value pair for a given hash is the one that is used. Is this documented anywhere?
    my $self = { %defaults, @_ };
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[d/l]
      As far as I know, it's only documented in the same sense as this bit of code: 
      my $x;
$x = 1;
$x = 2;

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[d/l]

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