Re^4: unless versus if ( ! ) inside a subroutine

[halley]

Conditionals are not always evaluated. The compiler can sometimes decide to phrase things differently.

U:\> perl -MO=Deparse -le "$x = 5; if ($x) { print $x }"
$x = 5;
if ($x) {
    print $x;
}

U:\>perl -MO=Deparse -le "$x = 5; if (0) { print $x }"
$x = 5;
'???';

U:\>perl -MO=Deparse -le "$x = 5; if (1) { print $x }"
$x = 5;
print $x;;

U:\>perl -MO=Deparse -le "$x = 5; if (! 0) { print $x }"
$x = 5;
print $x;;

[almut]

Sure, but in those cases, constants are being tested in the conditional, which allows the compiler to make optimisations. In the OP's example, though, $v is a regular (mutable) scalar variable, which could change its value at runtime (after the compiler has done its work)...