A nested function is a function defined inside another function. In Python, this means that the inner function has access to the variables and scope of the outer function. The inner function can also be returned by the outer function, allowing it to be called and used outside of the outer function's scope.
Here's an example of a nested function in Python:
def outer_function(x): def inner_function(y): return x + y return inner_function |
In the above example, outer_function takes a parameter x and defines an inner function inner_function that takes a parameter y. inner_function returns the sum of x and y. outer_function then returns the inner_function.
Here's an example of how to call the nested function:
closure = outer_function(10)print(closure(5)) # Output: 15 |
In the above example, the outer_function is called with x equal to 10. The inner_function is returned and assigned to the variable closure. The closure variable is then called with y equal to 5, which returns the sum of x and y (15).
Nested functions can be useful for a variety of reasons, including:
However, it's important to use nested functions sparingly and only when they make sense for the specific use case. Too many nested functions can make code harder to read and maintain.