Hello xorl,

You can make this kind of code cleaner by taking an OO approach. Create an abstract class Module with the common interface, and subclass it as Module::SuperCool, Module::AlmostCool, and Module::Uncool. Then create a Module object once:

use Module;
use Module::SuperCool;
use Module::AlmostCool;
use Module::Uncool;

my $module_instance = ($] >  5.010)  ? Module::SuperCool->new(...)  :
                     (($] <= 5.010) &&
                      ($] >  5.008)) ? Module::AlmostCool->new(...) :
                                       Module::Uncool->new(...);
...
$module_instance->frobnicate(...);
[download]

and use it as needed — there will be no need for switch statements using a $supercool flag.

Of course, Module::SuperCool will be implemented using super cool functions provided by cutting-edge CPAN modules; Module::AlmostCool will be implemented using less cool functions from older CPAN modules; and Module::Uncool will be implemented using your 10,000 lines of code.

Hope that helps,