my $q = CGI->new()

sub foo {
    my $thing = $q->param('thing');
}
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For at least my own education, if no one elses, how exactly is that a closure and why are people getting screwed doing it? It seems fairly simple to me..

It's a closure because the sub foo refers to $q, which is a lexical variable delcared in the enclosing scope. Now, for the rest of the life of this Perl interpreter, the $q inside of the foo subroutine will always have the same value it did the first time this code was run, no matter what you do in the main part of this program. That means you will get crazy results where CGI.pm appears to be caching data from previous requests.

It's a closure because it contains a reference to a lexical variable ($q) from a parent scope. It could cause problems if later you reassigned $q and thought it would change inside the sub, or thought it go away after the scope of $q ended.

kelan

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Perl6 Grammar Student