in reply to How can I access object data in a user defined sort cmp function?

(I came to the conclusion Guido was right about whitespace)

using global... I mean, local our variables. Just like $a and $b.
use strict; use warnings; sub sort_aux { our $self; $a <=> $b; } sub hash_ref_keys_by_value { local our $self = shift; my @keys = sort by_value keys %{ $self->{hash_ref} }; }