为什么 next(some_generator_func()) 与 next(a_var) 产生不同的结果，其中 a_var = some_generator_fun()？

Question

Let some_generator_func() be the function:

def some_generator_fun():
    yield 1
    yield 2

Why is it that

>>>>next(some_generator_func())
1
>>>>next(some_generator_func())
1

whereas

>>>>a_var = some_generator_func()
>>>>next(a_var)
1
>>>>next(a_var)
2

?

Answer 1

In your first case, you create a new generator expression each time you call the function. This means you will create a brand new generator, then call next which will effectively call the first element each time.

When you assign it to a variable, you are yielding elements from that generator each time you call next .

Answer 2

Calling some_generator_func creates a new iterator starting from the top of the function. Therefore, in the first case, you iterate two fresh iterators; in the latter case, you iterate the same iterator twice.