Case-insensitive dict, non-destructive, fast, anyone?

[Raymond Hettinger]

[Ville Vainio]
> I need a dict (well, it would be optimal anyway) class that stores the
> keys as strings without coercing the case to upper or lower, but still
> provides fast lookup (i.e. uses hash table).


>>> class S(str):
    def __hash__(self):
        return hash(self.lower())
    def __eq__(self, other):
        return self.lower() == other.lower()


>>> d = {}
>>> d[S('ThE')] = 'quick'
>>> d[S('the')]
'quick'
>>> d
{'ThE': 'quick'}


Raymond Hettinger