Correct ... check out require.

Note that the file will not be included twice under the same specified name.

Add into that mix that require happens at run-time, use at compile and the notion that require pulls in the current namespace and voila - your subs are in your client namespace. (replace &sub_x with &Client::sub_x to see).

And that's why I try not to mix require with use. If I have global functions -- then either create a base class and let your Client class inherit them or create a util class and let your Client class use them.