Python: Extending a predefined named tuple

Question

I have the following named tuple:

from collections import namedtuple
ReadElement = namedtuple(\'ReadElement\', \'address value\')

and then

Answer 1

Extending Martijn Pieters' answer: there is a way to make the new namedtuple class a subclass of the other, without having to hack. Simply create the new namedtuple separately, and then use its __new__ method instead of using super:

from collections import namedtuple

class ReadElement(namedtuple('ReadElement', ('address', 'value'))):
    def compute(self):
        return self.value + 1

_LookupElement = namedtuple('_LookupElement', ReadElement._fields + ('lookups',))

class LookupElement(_LookupElement, ReadElement):
    def __new__(self, address, value, lookups):
        return _LookupElement.__new__(LookupElement, address, value, lookups)

assert issubclass(LookupElement, ReadElement)
l = LookupElement('ad', 1, dict())
assert isinstance(l, ReadElement)
assert l.compute() == 2

It seems that this also works without even overriding __new__ !

from collections import namedtuple

class ReadElement(namedtuple('ReadElement', ('address', 'value'))):
    def compute(self):
        return self.value + 1

class LookupElement(namedtuple('LookupElement', ReadElement._fields + ('lookups',)),
                    ReadElement):
    """nothing special to do"""
    pass