Design question about pretree classifier

[Steve Holden]

Julian wrote:
> Hello,
> 
> I've got a design problem for a classifier. To make it short: it maps
> strings on strings.
> 
> Some strings have exactly one classification, some none and some more
> than one.
> 
> There's a method classify(self, word) wich classifies a word. For the
> first case there's no problem:
> 
> - one classification: return the value (it's a string)
> 
> But:
> 
> - none classification: return an exception or None? I think None is
> better, hence its not an exception that there is no classification but
> a defined state. What do you think?
> - many classifications: what to do? retun a sequence of strings? raise
> an exception and implement another method wich returns than the
> classifications? what should I do here?
> 
> thanks for your answers!

Always return a list or tuple. For no classifications it should be
empty, for one classification it should have one element, ... , for N
classifications it should have N elements.

regards
 Steve
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