What you're describing sounds to me like a modulino.

Update: In a nutshell, the way it's done is something like this: 

package Foo;

_run( @ARGV ) if ! caller;

sub _run {
    # Do stuff as a program
}

[download]

It's using caller to tell whether it's being executed "at the top level". If you search for modulino on CPAN, there are a few examples to look at.

In reply to Re: conditional self-execution by kyle
in thread conditional self-execution by apotheon

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