Hi all, I was playing with some code that uses an arrayref in various places, and started getting errors when i added some code and the arrayref was undef. Originally, there was something like: (all code has strict & warnings on, these are just snippets) 
   my $arrayref = getArrayref(); # this sometimes returned undef
   foreach my $value (@$arrayref) {
      ...
   }

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This worked ok, even when $arrayref == undef. So then i added an if conditional to the method: 
   if ( @$arrayref ) {
      ...
   }

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This resulted in a fatal error:

Can't use an undefined value as an ARRAY reference at ...

My co-worker and I discussed this and decided that it was an rvalue versus lvalue issue. But our resolution still doesn't sit very well in my mind.

Update:This is incorrect, it creates a fatal error.
If i put this line before the if, then things are ok:
@$arrayref
end update
But thats not cool, and results in a warning too.

Anyway, in the end i did the if statement as: 

   if ( defined($arrayref) && @$arrayref ) {
      ...
   }

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(perhaps i should be doing a ref test also, but the value of $arrayref is always set by the same method.)

So im looking for more insight into exactly why this is all behaves like it does. I sort of understand, but not completely.

I use the most powerful debugger available: print!

In reply to Using undef scalar as arrayref by shemp

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