Python Variable Scope

Python - Variable Scope:

Variable scope refers to the region of a program where a variable is accessible. Understanding scope is crucial for writing clean, bug-free code. In Python, there are mainly two types of variable scope: global scope and local scope.

1. Global Scope:

⤏ Variables declared outside of any function or class have global scope.

⤏ They can be accessed from anywhere within the program, including inside functions and classes.

⤏ To modify a global variable from within a function, you need to use the 'global' keyword.

# Python variable scope: Global
x = 10  # Global variable

def func():
    print(x)  # Accessing global variable

func()  # Output: 10

10

2. Local Scope:

⤏ Variables declared within a function or a class have local scope.

⤏ They can only be accessed from within that function or class.

⤏ Variables with the same name can exist both globally and locally without affecting each other.

def func():
    y = 20  # Local variable
    print(y)


func()  # Output: 20

# Accessing local variable outside the function will result in NameError
print(y)  # NameError: name 'y' is not defined

[Error] NameError: name 'y' is not defined

However, Python also supports a concept called "enclosing scope," which comes into play with nested functions. In the case of nested functions, a variable declared in an outer function is accessible in the inner function.

# Python variable scope: Local
def outer_func():
    z = 30  # Enclosing scope variable

    def inner_func():
        print(z)  # Accessing enclosing scope variable

    inner_func()

outer_func()  # Output: 30

30

Note: You can also use the 'nonlocal' keyword, which allows you to modify variables in the enclosing scope from within nested functions.

nonlocal x
        x = 20  # Modifying variable in the enclosing scope