Technically in Perl, a "use" statement is asking for those manipulations, though. If you want to just load the library but not ask for any of those things, you would require the library, either in or not in a BEGIN block depending on your desires. If, however, merely "require"ing the library performed any of those manipulations, that would be a violation of what I'd expect. (Of course, if the sole purpose of your module is to perform those manipulations, "require" may not do anything useful, but I'd still expect it not to do anything to my local namespace, either.)