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this. At least with the current example and even the surrounding chatter in this thread, I don’t see any benefit and plenty of room for downsides. Some of which haven’t even been mentioned yet (e.g how this will play with IDEs)

I don’t mean to poo poo on it. I really do like learning new patterns, but I haven’t yet grasped this one’s utility.

You could modify it easily, for example the user could register an additional function to the mapping. That would not be as easy to do with a module and getattr().

You can also list the registered function with math_exprs.keys() and that might not be as easy with a module either.

if all the keys are unknown until runtime then I guess the dict makes sense

I don't think it makes much sense in the example code given

You use it to dispatch to the appropriate function in a module based on the value of a runtime variable