7.15 Generators

Closely related to an iterator is the Python concept of a generator. A generator g is a special function with this behavior:

• The first time you call g, it initializes itself, passes back a value, and freezes its state.
• The next time you call g, it continues processing until it passes back a value and then freezes its state again.
• These actions continue until the function terminates, and then it returns no additional values.

We use yield to tell Python to pass back a value and freeze everything until the next call to the generator.

def create_odd_number_generator():
    n = 1
    while True:
        yield n
        n += 2

odd_number_generator = create_odd_number_generator()
odd_number_generator

<generator object create_odd_number_generator at 0x0000024A93102660>

next(odd_number_generator)

1

next(odd_number_generator)

3

...