That was me, however I was not trying to solve the "uninitialized value used in concatenation" problem. I used that as an example of something that was able to tell if it had been set before or not. And indeed, defined did the same thing, I had assumed (incorrectly) that if I had done my $a = undef, it would have thought the value was 'initialized' and not generate that error. I chock this up to the use of uninitialized instead of undefiend in the warning message.

I was trying to create a behavior that depended on if someone had tried to assing a value, even undef, to a variable. So 'my $a' and 'my $a = undef' would result in different behavior.

This is of course not possible, but I did not know that, and I was very confused. Also this was in the IRC channel, and it was very hard to define my question with enough information to prevent people from assuming I was trying to do something that could be solved with the 'defined' check.

How could I have handled this better? Was it just a communication breakdown cause I was trying to do something impossible that closely resembled something that was possible? Or did I just choose a really bad example?