Logical or and Exclusive Or
Binary "or" returns the logical disjunction of the two surrounding expressions. It's equivalent to || except for the very low precedence. This makes it useful for control flow:
1 | print FH $data or die "Can't write to FH: $!"; |
This means that it short-circuits: the right expression is evaluated only if the left expression is false. Due to its precedence, you must be careful to avoid using it as replacement for the || operator. It usually works out better for flow control than in assignments:
1 2 3 | $x = $y or $z; # bug: this is wrong($x = $y) or $z; # really means this$x = $y || $z; # better written this way |
However, when it's a list-context assignment and you're trying to use || for control flow, you probably need "or" so that the assignment takes higher precedence.
1 2 | @info = stat($file) || die; # oops, scalar sense of stat!@info = stat($file) or die; # better, now @info gets its due |
Then again, you could always use parentheses.
Binary "xor" returns the exclusive-OR of the two surrounding expressions. It cannot short-circuit (of course).
There is no low precedence operator for defined-OR.
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