From perldiag (I think this is only in 5.6, so perlmonks doesn't have it) :
No such pseudo-hash field ""%s"" (F) You tried to access an array as a hash, but the field name used is not defined. The hash at index 0 should map all valid field names to array indices for that to work.
Without seeing how your pseudohash is created I imagine that the structure of the array behind $foo, or its hash members is not what you think, or simply doesn't contain the 'blah' key.

Additionally, perl is probably interpreting @$foo as a pseudohash is because your sort routine references them as such :

$a->{'blah'} cmp $b->{'blah'}
maybe
$$a->{'blah'} cmp $$b->{'blah'}
would work, but I'm really just guessing there, since your data structure isn't apparent.

In reply to Re: Pseudo-hash intrusion... (boo) by boo_radley
in thread Pseudo-hash intrusion... by dragonchild

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":