Yeah...I'm guilty of learning what I needed to learn to make things work, then not learning much else until I needed to make something else work. So having learnt to require *.pl files, I have just kept doing it.

Maybe I could claim I write fashionably retro code :P

My first reaction on seeing require of a .pl file is that it is very old code. I would call it a code smell.

I prefer to put as much code as possible in CPAN-style modules (.pm files), with associated unit tests (.t files) for each module.

The ideal is for commands (.pl files) to be very very short, with almost all automated testing heavy lifting delegated to the module level, leveraging the excellent Perl CPAN module testing tools, such as the prove command. An extreme example of this approach is Perl::Tidy whose perltidy command is essentially just:

use Perl::Tidy;
my $arg_string = undef;
exit Perl::Tidy::perltidy( argv => $arg_string );
[download]

I prefer to put as much code as possible in CPAN-style modules (.pm files), with associated unit tests (.t files) for each module.

Oh!
That's what those *.t files are for...

Now I am reading Test::Tutorial which is something else I didn't know existed.