Thank you both for your answers. I didn't realize that $_ was not local, that explains it indeed.

But now I have a follow up question: I don't understand why the values in the hash are affected? In my mind I assumed that $_ receives a copy of the ref to the object, so I didn't expect that when $_ is set to undef the values in the hash become undefined as well. Here is an example of what I mean:

my @docsObservs;
foreach my $docP (values %{$self->{docs}}) {
  push(@docsObservs, $docP->getObservations());
  die "loop variable is undef after call to getObservations()" if (!de
+fined($docP));
  $docP = undef;
}
map { die "bug after!" if (!defined($_)); } values %{$self->{docs}};

[download]
It turns out that this version dies with the "bug after" error. Is this somehow related to how the values function works? It looks as if $docP is some kind of "hard link" to the object, and not a simple copy of the ref.

In reply to Re: Strange bug with map by erwan
in thread Strange bug with map by erwan

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