Yes sure, I see what you mean, but I think you're kinda mixing two separate issues here — so it wasn't immediately clear to me, with which you wanted help.

For one, there's the question of how to avoid to inadvertendly import stuff into your namespace that might clash with something else (this is what I tried to answer).

Then, there's the problem of accidentally introducing something in the inheritance hierarchy which does interfere with the so far established lookup mechanics in the code. For the latter problem it's irrelevant whether you import access from POSIX, or whether you yourself happen to write a new routine MyCGI::access. If it's found first along the inheritance chain for a certain type of object, it will be called - that's it. I don't think there's much you can do to prevent this from possibly happening within the standard Perl5 OO framework.

OTOH, I have to say that I personally cannot remember to have ever encountered that type of problem in practice within the last decade of my programming in Perl5 (and I've used quite a number of modules during that time). But maybe I just don't recall the incidence, because it was trivial to diagnose and fix... Dunno.