Generic functions in PyProtocols

Mar 6, 2005 05:38 · 178 words · 1 minute read

There are certain situations where generic functions make a whole lot of sense. (If you find yourself writing a method or function with a bunch of if/elif/else cases, you might be looking at one of these situations.) This week, I had a clear cut case of rules that I wanted to combine in a certain way and to also allow extensions of the rules. The PyProtocols dispatch package made this straightforward.

I ran into a situation where two rules applied equally well. The standard combination mechanism throws an exception in this case, rather than making an arbitrary choice as to which should apply. I wrote my own combination function already, but I’m still glad to see a new page of documentation specifically about result combination: CombiningResults – The PEAK Developers’ Center.

Generic functions are a handy tool to have in your belt. Sure, anything you can do with them you could have done before. But, some problems feel like a class or interface is the right solution, other problems feel like a generic function is a better fit.