在Python中创建任意对象的副本并调用构造函数

Question

I have classes A , B , and C which inherit from Foo . Their __init__ methods all do different things, but have a similar signature: they all take a single parameter i in __init__ . Some number of instances of these classes are in a list l , and all mixed together. In l , all the objects have i=1 .

I need to go through l , and for every object I see, I need to create the same object, but instantiated with i=2 instead of i=1 .

How do I do this?

I tried this:

l2 = []
for obj in l:
    obj_2 = type (obj).__init__(2)
    l2.append(obj_2)

But it didn't work.

Answer 1

I'm not sure what you mean by "create the same object". If you mean "create a brand-new distinct object of the same type", then try this:

obj_2 = type (obj)(2)

Your code, rewritten as a list comprehension:

l2 = [type(obj)(2) for obj in l]