note anazawa <p>When we execute my code above, the script throws an exception because <code>&{ 'run' }</code> violates "strict refs". Khen1950fx explained how to avoid this problem (I appreciate his suggestion).</p> On the other hand, when we comment out <code>&{ 'run' }</code>, my script doesn't output error messages. This result shows the following doesn't violate "strict refs": <code> my $walkable = defined &{ 'walk' }; undef &{ 'walk' }; </code> It seems each line uses symbolic references. I don't understand why this is possible. 988541 988617