LEGB Rule in Python

• Local Scope: Variables defined within a function are said to have local scope. That means they can only be accessed within that function.
• Enclosing Scope: In Python, functions can be defined within other functions. If a variable is not defined in the inner function (local scope) it will be looked for in the enclosing function.
• Global Scope: If a variable is not found in the local or enclosing scopes, Python will look for it in the global scope. These are variables defined outside all function definitions.
• Built-in Scope: If a variable isn’t found in any other scope, Python will look for it in the built-in scope. These are predefined variables in Python like print(), id(), etc.

Examples:

Local Scope:

def local_example():
    local_var = 'I am local'
    print(local_var)
local_example()  # prints: I am local
    

Enclosing Scope:

def outer_func():
    enclosing_var = 'I am enclosing'
    def inner_func():
        print(enclosing_var)
    inner_func()  # prints: I am enclosing
outer_func()
    

Global Scope:

global_var = 'I am global'
def global_example():
    print(global_var)
global_example()  # prints: I am global
    

Built-in Scope:

def built_in_example():
    print(len([1, 2, 3]))  # len is a built-in function
built_in_example()  # prints: 3