Your example works for me too. Sorry. Apparently I took the error out of my code while reducing it to a simpler test case. My production code still exits with "Not a CODE Reference". I tried debugging it, but I do not understand why it crashes while evaluating the if-expression. 
1357==>b if ($self->{TT}->call_category($key) != undef)
1358        {
1359            # Do something, never reached
1360        }

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use Data::Dumper;
print Dumper $key
$VAR1 = 'AN-AM-BA';

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print Dumper $self->{TT}->call_category
$VAR1 = {
          'DU-EX-TA' => 16,
          '*-CM-*' => 145,
          # Lots more, but not the value of $key.
          '*-VY-*' => 132
        };

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print Dumper $self->{TT}->call_category($key)
$VAR1 = undef;

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n
Not a CODE reference at ...

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Do you have any pointer what's wrong here?

In reply to Re^2: Class::Struct - Not a CODE referemce by ungerma
in thread Class::Struct - Not a CODE referemce by ungerma

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