Don't get me wrong, I'm all for using modules. It's just that base.pm is a bit of a special case in that, when I see it at least, I immediately think that the package from which it's "use"d also uses fields.pm.

If base.pm was just syntactic sugar for pushing onto @ISA, I'd be more inclined to use it. But its usage seems (to me anyway) to imply that fields.pm is also in the mix. Even if it's not, there's no way to tell from the "use base" line alone.

I tend not to "use base" so no one will erroneously suspect that I'm using fields.pm and (probably more importantly) to avoid implying that one needs to "use base" if in order to subclass my class cleanly.