On Wed, Sep 11, 2013 at 06:08:25AM -0500, Skip Montanaro wrote:
(I still don't care for the name. "Transform" != "case folding" in my mind. A quick scan of your links suggests most people think something like "cidict" or "CaseInsensitiveDict" would be more descriptive.)
But the proposal is not for a case-insensitive dict. It is more general than that, with case-insensitivity just one specific use-case for such a transformative dict. Arguably the most natural, or at least obvious, such transformation, but there are others. I have code that does something like this: MAPPING = {'spam': 23, 'ham': 42, 'eggs': 17} result = MAPPING[key.strip()] # later... answer = MAPPING[key] # Oops, forgot to strip! This is broken. Using Antoine's proposal: MAPPING = TransformDict(str.strip) MAPPING.update({'spam': 23, 'ham': 42, 'eggs': 17}) result = MAPPING[key] # later... answer = MAPPING[key] # Fine now. so that the mapping handles stripping the keys, not the caller. This isn't just about strings, and certainly not just case-insensitivity. -- Steven