yield

Used to create generators/iterators (there’s a small difference, but it’s minor) (e.g., enumerate) (range(start, stop, step) is not a iterator, it is more of a function to generate a string of numbers from start to stop - 1, incrementing my step each time).

Since the function with yield is now a iterator, the next() function applies to it. (get the next value from the iterator)

def fun(m):
    for i in range(m):
        yield i  

for n in fun(5):
    print(n)

You can think of it as like a return that doesn’t make the function exit. When you call the function, the function will yield the expression after the yield keyword.

Advantages:

• Infinite sequences (you can create a function that yields the numbers in a fibonacci sequence for example)
• Since yield allows you to “pause”/resume the function, it’s good for async programming
• Fine-grained control over iteration
• Memory-efficient, everything comes when you want it to, and not all at once too
• The state inside the function with yield retains the state it was on.

#python #python/features