We've previously seen how to create a nested function in Python.
If you return a nested function from a function, that nested function has access to the variables defined in that function, even if that function is not active any more.
Here is a simple counter example.
def counter():
count = 0
def increment():
nonlocal count
count = count + 1
return count
return increment
increment = counter()
print(increment()) # 1
print(increment()) # 2
print(increment()) # 3
We return the increment()
inner function, and that has still access to the state of the count
variable even though the counter()
function has ended.