Python decorating property setter with list [duplicate]

Answer 1

I would subclass list and override a few methods:

import itertools

class ExtendedList(list):
    def __init__(self, other=None):
        self.other = other or []

    def __len__(self):
        return list.__len__(self) + len(self.other)

    def __iter__(self):
        return itertools.chain(list.__iter__(self), iter(self.other))

    def __getitem__(self, index):
        l = list.__len__(self)

        if index > l:
            return self.other[index - l]
        else:
            return list.__getitem__(self, index)

It should work with just about everything:

In [9]: x = ExtendedList([1, 2, 3])

In [10]: x
Out[10]: [1, 2, 3]

In [11]: x.append(9)

In [12]: x
Out[12]: [9, 1, 2, 3]

In [13]: x.extend([19, 20])

In [14]: x
Out[14]: [9, 19, 20, 1, 2, 3]

In [15]: sum(x)
Out[15]: 54