LanX has asked for the wisdom of the Perl Monks concerning the following question:

Hi according to the perldocs of Tie::Hash this works 
      sub STORE    {
        warn "Storing data with key $_[1] at $_[0].\n";
        $_[0]{$_[1]} = $_[2]
      }

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and in my tests it does, but I don't really understand why, because $_[0] is supposed to be a reference(!) and is not properly dereferenced here. Looking into the source of Tie::Hash reveals the expected usage. 
package Tie::StdHash;

...

sub TIEHASH  { bless {}, $_[0] }
sub STORE    { $_[0]->{$_[1]} = $_[2] }

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I'm confused, is there any aliasing magic in $_[0] making it act as a non-refrence hash variable?

Cheers Rolf

Replies are listed 'Best First'.
Re: Confused about $self in Tie::Hash
by choroba (Cardinal) on Oct 12, 2011 at 15:48 UTC
    The arrow is optional after a hash key or array index, it is mandatory only after the scalar containing a reference. Thus,
    $h_ref->{key};
$a_ref->[1];
$h_ref->{key}{deeper};
$h_ref->{key}[2];
$a_ref->[0][1];
$a_ref->[1]{inside};
$arr[0][1];
$hash{key}{deeper};

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    are all OK.
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[d/l]
      Argh, thanks you're right.

      ( I stopped looking at $_[0] as an array element of @_. )

      Cheers Rolf

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