编写一个返回 dict 或 OrderedDict 的函数会是 Pythonic 吗？

Question

I am in doubt if a regular dict and an OrderedDict objects are truly interchangeable in a sense that the same function or method could return once a dict and other times an OrderedDict depending on the input arguments or for example in case of a class method depending on some other internal class instance attributes. If returning an OrderedDict would be significantly more costly than returning just a regular dict which should suffice as well why doing it the hard way? Would it be pythonic to create such a function or menthod? I use Python 2.7.

I have seen "Why should functions always return the same type?" and I felt my case is more special and less obvious to the unseasoned eye.

Answer 1

Python uses duck typing. as long as an object presents the necessary interface required for an action, the type of object is irrelevant. An OrderedDict will present all the interfaces a dict would, so what the function returns is irrelevant. It'll be up to whatever uses what was returned. You should figure out the implementation of the use not the returning function.

What's your use case? Detailing that would help in suggesting an answer or alternatives.