Hi xorl,

The other solutions so far by Athanasius, Corion and MidLifeXis are cleaner and easier to maintain, and I would also suggest wrapping the functionality in a module that abstracts your Cool modules. But just for completeness, here's one way to directly implement the code you've shown (untested Update: now tested, and fixed a bug):

my $SUPERCOOL;
BEGIN {
    if ( ($] ge '5.010') && eval("use Super::Cool::Module; 1") )
        { $SUPERCOOL = 2 }
    elsif ( ($] lt '5.010') && ($] ge '5.008')
            && eval("use Almost::Cool::Module; 1") )
        { $SUPERCOOL = 1 }
    else
        { $SUPERCOOL = 0 }
}
[download]

You don't even have to make the conditions dependent on the versions, you can just try to use several modules and take whichever one is available. And a note on $]:

When comparing $], string comparison operators are highly recommended. The inherent limitations of binary floating point representation can sometimes lead to incorrect comparisons for some numbers on some architectures.

Hope this helps,
-- Hauke D