Re: Assignment to a value only if it is defined

If you're using Perl 5.10, you have the defined-or operator //:

$foo //= $bar; # equivalent to $foo = $bar if defined $bar;
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Re^2: Assignment to a value only if it is defined by JavaFan (Canon) on Jan 20, 2010 at 10:56 UTC
Wrong. That's equivalent to `$foo = $bar unless defined $foo;` [download] What the OP wants is: `$foo = $bar // $foo;` [download] which is equivalent to `$foo = $bar if defined $bar;` [download] assuming the absence of ties and overloading.	[reply] [d/l] [select]
Re^2: Assignment to a value only if it is defined by almut (Canon) on Jan 20, 2010 at 10:48 UTC
not quite — `$foo //= $bar` would test if `$foo` is defined, not `$bar` (it's equivalent to `$foo = $bar unless defined $foo`).	[reply] [d/l] [select]