Python nonlocal keyword

If you are unable to think clearly about nonlocal keyword, you are at the right place. This article will provide you brief information about the use of nonlocal factors, and how they are unique in relation to neighbourhood and worldwide factors.

The nonlocal is a reserved keyword of Python, which is used in nested functions whose local scope is not defined. The necessity is that the variable shouldn't belong to the inner function's scope, therefore we define it in the outer function and use it inside the inner function as a nonlocal variable. This implies that the variable can be neither in the local nor the global scope. The nonlocal keyword is used to indicate that a variable is in the nonlocal scope. It binds one or more variables to the outer scope.

Syntax of nonlocal keyword

nonlocal variable_name

Example of nonlocal keyword

Here is the python program to demonstrate the example of nonlocal variable. In this, we have defined two variables x and y in both the outer function and the inner function. We are binding variable x as nonlocal in the inner_func() function, that's why x is not local to the inner function and update with newly assigned value, but y will be considered as a local variable for inner_func().

# python code to show an example 
# of nonlocal keyword 

# nested functions
def outer_func():
    x = 20
    y = 40

    # nested inner function
    def inner_func():
        # nonlocal variable binding
        nonlocal x
        x = 100 
        y = 200
        print("Inner variable x : ", x) 
        print("Inner variable y : ", y) 
    
    # calling inner function
    inner_func()

    print("Outer variable x : ", x) # x updated as nonlocal
    print("Outer variable y : ", y) # y is considered as local variable
    
# main code
outer_func()

Output of the above program

Here is another Python program that demonstrates the nonlocal keyword. It is the same as the above, but the variables x and y are of type strings.

# python code to show an example 
# of nonlocal keyword 

# nested functions
def outer_func():
    x = "local variable x"
    y = "local variable y"

    # nested inner function
    def inner_func():
        
        # nonlocal variable binding
        nonlocal x
        x = "Non local variable x"
        y = "Non local variable y" 
        print("Inner variable x : ", x)
        print("Inner variable y : ", y) 
    
    # calling inner function
    inner_func()

    print("Outer variable x : ", x) # x updated as nonlocal
    print("Outer variable y : ", y) 
    
# main code
outer_func()

Output of the above program Non local variable