Essentially, what appears within the tie function must have a sigil. That means that tie expects an actual hash, not a hashref. The {...} anonymous hash constructor returns a hashref, which doesn't work. For example:

tie( %hash, 'Class' );
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...is valid, but ...

tie( { anon => 'hash' }, 'Class' );
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...is not valid. However, you can tie the nested portions of nested datastructures like this:

my $href = {};
tie( %{$href}, 'Class' );
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...or even...

my( %hash ) = ( 'this' => {},
             'that' => {} );
tie( %{$hash{'this'}}, 'Class' );
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Also note, definately it is not doing what you expect if you do this:

my( %hash ) = tie( %otherhash, 'Class' );
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...because tie doesn't return the tied hash, it returns the tied object's instance reference. Since you're assigning the object's reference to %hash, you'll stringify the object ref and turn it into a hash key in %hash with undef as the value. So don't do that. In other words, this does work:

my $obj = tie( %hash, 'Class' );
$obj->DESTROY;
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