replace %(word) in a string

[Skip Montanaro]

    Fred> Yes, that's a wonderful feature. Recently though, I've wondered a
    Fred> couple of times : is there an easy way to substitute with both
    Fred> local AND global variables ?...

Sure, search the list archives for something like EvalDict.  Basically, you
want a class which behaves like a dict, but will search through multiple
dictionaries looking for matching keys.

Skip