Re^3: Integer detection concept

That's because it's not a closure. Closures are subroutines that maintain the lexical state around them outside the scope of that lexical state. There's no subroutine involved.

The reason for the extra brackets is to provide a scope for the local $^W = 1;.

Being right, does not endow the right to be rude; politeness costs nothing.
Being unknowing, is not the same as being stupid.
Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence.
Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.

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Re^4: Integer detection concept by Tanktalus (Canon) on Jan 19, 2005 at 16:46 UTC
Look a bit more closely. There is an anonymous sub there which gets called by the perl runtime in event of a warning.	[reply]
Re^5: Integer detection concept by dragonchild (Archbishop) on Jan 19, 2005 at 17:51 UTC
Which is never called outside the context of the same lexical pad. All it does is affect a variable outside of its scope. The key is that it's been assigned to `local( $SIG{WARN} )` - the sub disappears when the scope goes away. It's kinda the opposite of a closure, if you think about it. Instead of a subroutine being called outside the scope of a lexical variable yet still affecting it, you have a variable being used outside of the lexical scope of the subroutine that affected it. Being right, does not endow the right to be rude; politeness costs nothing. Being unknowing, is not the same as being stupid. Expressing a contrary opinion, whether to the individual or the group, is more often a sign of deeper thought than of cantankerous belligerence. Do not mistake your goals as the only goals; your opinion as the only opinion; your confidence as correctness. Saying you know better is not the same as explaining you know better.	[reply] [d/l]
Re^6: Integer detection concept by Tanktalus (Canon) on Jan 19, 2005 at 18:00 UTC
I would think that's still a closure. Since it is called outside of the lexical scope of the lexical variable. When a signal is caught, we're in the signal handling part of the perl runtime. That is far, far outside of the lexical scope of $warn. So, Perl_warn_handler() calls the coderef it is given, which affects $warn, which is outside of the scope of Perl_warn_handler(). That, to me, is a closure.	[reply]