caller always returns the package where the code was, regardless of which name in which package you used to call the code.

I see, this explains why my first attempt had to fail.

Actually, the reference you gave was very helpful, because what my do_something *really* does, is to call NEXT(). I just left out this detail because I thought it would not be relevant to the problem.

I just wonder whether fiddling around with __ANON__, as shown in the example you refered to, is considered portable Perl style (I couldn't find any "official" Perl documentation about __ANON__), or whether the eval solution I used would be better. Both seem to be a hack, but which one is the kinder hack ?-)