use base loads the base class if it is not already loaded, so you do not need to explicitly load it before.
use base does much more than just loading a base class and setting up inheritance, and most times, you don't need that. use parent loads the base class and sets up inheritance, and that's all it does. So I would recomment to use parent instead of base.
There is no need to inherit from Exporter at all (unless you want to support perl 5.8.2 and older), use Exporter 'import' is sufficient for your code and most other cases. (See also Re: Advice on style and Re^2: Advice on style).
Alexander
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Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)