You can't rely on warnings to tell you var didn't exist in the file, and you have no control over whether var gets defined.

Not true: 

while (<FILE1>) {
  $var = GetVar($_) || $some_reasonable_default;
};

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$var is now guaranteed to have a defined value on every iteration, regardless of the file's contents. Granted, there are cases where there is no reasonable default, but, as the programmer, I do still have control over whether $var is defined or not, should I choose to exercise it.

In reply to Re^4: Breaking The Rules by dsheroh
in thread Breaking The Rules by Limbic~Region

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