undef $bar may have some useful side-effects, if $bar is an object. 
$bar = Foo->new();
...
undef $bar;

[download]
will invoke "Foo::DESTROY", if it is defined. 
$bar = 0;

[download]
will also invoke DESTROY, but not if '0' is a valid assignment in the "Foo" class (long shot, I know).

In reply to Re: undef vs. $foo = 0 by Mur
in thread undef vs. $foo = 0 by DaWolf

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