Kay Schluehr wrote:
Maybe also the subclassing idea I introduced falls for short for the same reasons. Adding an accumulator to a dict should be implemented as a *decorator* pattern in the GoF meaning of the word i.e. adding an interface to some object at runtime that provides special facilities.
Usage:
d = intdict(extend=MyAccumulator) hasattr(d,"tally")
True
hasattr(d,"appendlist")
False
This could be generalized to other fundamental data structures as well.
Regards Kay
Or similarly, something like the 'reversed' view of a sequence:
I could imagine a class: accumulator(mapping, default, incremetor) such that:
>>> my_tally = accumulator({}, 0, operator.add)
or
>>> my_dict_of_lists = accumulator({}, [], list.append)
or
>>> my_dict_of_sets = accumulator({}, set(), set.add)then: .accumulate(key, value) "does the right thing" in each case.
a bit cumbersome, because of having to specify the accumulation method, but avoids adding methods to, or sub-classing dict
Michael
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