Stephen Thorne wrote:
As for the overall efficiency concerns, I feel that talking about any
of this is premature optimisation.
I disagree -- using REs is adding unnecessary complication and dependency. Premature optimization is a matter of using a conceptually more-complicated method when a simpler one would do; REs are, in fairly simple cases such as this, clearly *not* simpler than dict lookups.
The optimisation that is really required in this situation is the same as with any large-switch-statement idiom, be it C or Python. First one must do a frequency analysis of the inputs to the switch statement in order to discover the optimal order of tests!
But if you're using a dictionary lookup, then the frequency of inputs is irrelevant. Regardless of the value of the input, you're doing a single hash-compute and (barring hash collisions) a single bucket-lookup. Since dicts are unordered, the ordering of the literal (or of a set of statements adding to the dict) doesn't matter.
Jeff Shannon Technician/Programmer Credit International
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