In Python, the nonlocal keyword is used to access a variable defined in the nearest enclosing scope that is not the global scope. This means that it allows you to modify a variable that is defined in a scope outside of the current function. Look at the following example:
def outer_function(): x = "outer" def inner_function(): nonlocal x x = "inner" inner_function() print(x) outer_function()
In this example, we have defined two functions: outer_function and inner_function. The variable x is defined in the outer_function and initialized to "outer". The inner_function modifies the value of x to "inner" using the nonlocal keyword, which allows it to access the x variable defined in the outer_function. When we call outer_function, it prints the value of x, which is now "inner" because it was modified by inner_function.
It is important to note that nonlocal can only be used to access a variable in the nearest enclosing scope that is not the global scope. If there is no such variable defined, a SyntaxError will be raised. Additionally, the nonlocal keyword cannot be used to modify a variable in the global scope; in that case, you would need to use the global keyword instead. Here is another example:
def outer_function():
x = 10x
def inner_function():
nonlocal x
x = x + 5
print("Inner function: x =", x)
inner_function()
print("Outer function: x =", x)
outer_function()
By running the above code the output would be like this:
Inner function: x = 15 Outer function: x = 15