I probably should have been more careful. It is necessary that your module return something true, and the easiest way to make sure that it does is to put 1; at the end of the source file ^*. All that I was saying was that what is actually returned may be anything true, including 1, "I'm a true string", or [ qw/references are always true/ ].

To put it briefly: don't leave off the 1; at the end without a good reason (although the good reason may be “I thought of something funnier”). If you do leave it off, then do a simple test import of your module just to make sure that it can be done.

^* To be precise, this requires that you haven't done something tricky earlier, like returning earlier in the source file.