Write a generator or return a generator?

Question

Inside a container class, when I want to iterate over its items (or transformations of its items, or a subset of its items), I can either write a generator (like f) or return a generator (like g):

class SomeContainer:
    def __init__(self):
        self.data = [1, 'two', 3, 'four']

    def f(self):
        for e in self.data: yield e + e

    def g(self):
        return (e + e for e in self.data)

sc = SomeContainer()
for x in sc.f(): print(x)
for x in sc.g(): print(x)

I do not need to pass information into the generator via send.

Apparently both ways behave identical (at the surface).

1. Which approach is preferable and why?

2. Which approach creates less overhead or has other advantages I fail to spot?

Answer 1

Generator comprehensions (such as in g()) would be slightly faster.

Explicit loops (such as in f()) would probably be more readable if your logic beccomes more complex than in the simple example you provided.

Other than that, I can't think of any material differences.

But remember what they say:

Premature optimization is the root of all evil!