python equivalent of functools 'partial' for a class / constructor

Question

I want to create a class that behaves like collections.defaultdict, without having the usage code specify the factory. EG: instead of

class Config(collectio         


        

Answer 1

If you actually need working explicit type checks via isinstance, you can simply create a not too trivial subclass:

class Config(collections.defaultdict):

    def __init__(self): # no arguments here
        # call the defaultdict init with the list factory
        super(Config, self).__init__(list)

You'll have no-argument construction with the list factory and

isinstance(Config(), Config)

will work as well.