Nested functions

Introduction to Functions in Python

Hugo Bowne-Anderson

Instructor

Nested functions (1)

def outer( ... ):        
    """ ... """
    x = ...

    def inner( ... ):    
        """ ... """
        y = x ** 2
    return ...

Nested functions (2)

def mod2plus5(x1, x2, x3):
    """Returns the remainder plus 5 of three values."""

    new_x1 = x1 % 2 + 5
    new_x2 = x2 % 2 + 5
    new_x3 = x3 % 2 + 5

    return (new_x1, new_x2, new_x3)

Nested functions (3)

def mod2plus5(x1, x2, x3):
    """Returns the remainder plus 5 of three values."""

    def inner(x):
        """Returns the remainder plus 5 of a value."""
        return x % 2 + 5

    return (inner(x1), inner(x2), inner(x3))

print(mod2plus5(1, 2, 3))

(6, 5, 6)

Returning functions

def raise_val(n):
    """Return the inner function."""

    def inner(x):
    """Raise x to the power of n."""
        raised = x ** n
        return raised

    return inner

square = raise_val(2)
cube = raise_val(3)
print(square(2), cube(4))

4 64

Using nonlocal

def outer():
    """Prints the value of n."""
    n = 1

    def inner():
        nonlocal n
        n = 2
        print(n)

    inner()
    print(n)

outer()

2
2

Scopes searched

Local scope
Enclosing functions
Global
Built-in

Let's practice!

Introduction to Functions in Python