While several people have given you good answers for what you are trying to do, maybe you should examine why you are trying to do it.

IMO (so take it for what its worth) this seems like a nasty hack that could bite you or someone else down the road when you try to maintain this code. Its much better to write your modules in such away that they simply return what you want rather than outputting something to STDOUT. Also, while using do in this manner is not depreciated perldoc clearly states that using use or require is generally a better idea for importing code.

Finally, nitpick: Perl modules most often end in a '.pm' or '.pl' extension, a good idea because then anyone else who might maintain your code in the future will know that it is a perl module. (Sorry my hatred of PHP gets the better of me from time to time :) )

Chris