How to use list comprehension in list derived class

Question

I have a list derived class and want to assign its contents using list comprehension This is the sample code:

class MyList(list):
    def __init__(self, some_data):
        self = [Foo(x) for x in some_data]

    def customFilter(self):
        self = [x for x in self if x.Selected]

Of course this does not work because the assignment to self just creates a local variable. Is there a pythonic way to achieve this without using for loop?

Answer 1

It's probably better to use Collections.UserList, which is made for subclassing. It gives you a data property which holds the lists contents and avoids the problem of assigning to self:

from collections import UserList

def Foo(c):
    return c * 2

class MyList(UserList):
    def __init__(self, some_data):
        self.data = [Foo(x) for x in some_data]

MyList([1, 2, 3])
# [2, 4, 6]