🧩 Scope and Modules in Python

Scope refers to the area of your program where a variable is recognized.

A module is just a file that contains Python code — functions, variables, or classes — which you can reuse.

🧩 Local Scope in Python

A variable defined inside a function is local to that function.

  def my_func():
      x = 10  # ✅ Can access inside only
      print(x)

  my_func()  # ✅ Works
  print(x)   # ❌ Error: x is not defined outside
            

🧩 Global Scope in Python

A variable defined outside any function is accessible globally.

  x = 50

  def show():
      print(x)  # ✅ Can access inside global variable

  show()
  print(x)  # ✅ Can access outside global variable
            

🧩 The global Keyword in Python

Use global if you want to modify a global variable inside a function.

  x = 5

  def modify():
      global x # ✅ modify global variable x
      x = 10

  modify()
  print(x)  # Output: 10
            

🧩 The nonlocal Keyword in Python

nonlocal allows modifying variables (Inside Nested Functions) from the outer enclosing function, not the global one.

  def outer():
      x = "Python"
      def inner():
          nonlocal x
          x = "Scope"
      inner()
      print(x)

  outer()  # Output: Scope
            

🧩 Scope of Objects and Names in Python

In Python, when you create a variable (name), it is stored in a namespace, and its scope decides where it can be accessed.

Python uses the LEGB Rule to decide which variable to use:

  x = "Global"

  def outer():
      x = "Enclosing"

      def inner():
          x = "Local"
          print(x)  # 🔍 Prints Local

      inner()
      print(x)      # 🔍 Prints Enclosing

  outer()
  print(x)          # 🔍 Prints Global
            

🧩 LEGB Rule Order of Scope in Python

🧩 L - Local scope in Python

Variables defined inside a function are local. They can only be accessed within that function.

  def show():
      x = 10  # Local variable ✅
      print(x)     # Accessing local variable ✅

  show()  # Output: 10 ✅

  print(x)  # ❌ Error: 'x' is not defined outside the function
            

🧩 E - Enclosing scope in Python

Variables defined in an outer function, but not in the global scope. These variables are accessible to inner (nested) functions.

  def outer():
      x = 10  # Enclosing variable ✅
              
      def inner():
          print(x)  # Accessing enclosing variable ✅
              
      inner()  # Output: 10 ✅
      print(x)  # Output: 10 ✅

  outer()

  print(x)  # ❌ Error: 'x' is not defined outside the function
            

🧩 G - Global scope in Python

Variables defined at the top level of the script or module. They are accessible throughout the entire script, including inside functions (unless shadowed by local variables).

  x = 10  # Global variable ✅

  def outer():
      def inner():
          print(x)  # Accessing global variable ✅
      inner()  # Output: 10 ✅
      print(x)  # Output: 10 ✅

  outer()
  print(x)  # Output: 10 ✅
            

🧩 B - Built-in scope in Python

Definition: The built-in scope contains all the standard Python functions and objects, like print(), len(), etc. These are always accessible in any Python script.

  def len(x):  # ❌ Overwriting built-in 'len' function
      return 0  # ❌ Always returns 0

  x = len('Python')  # ❌ Calls custom 'len', not built-in
  print(x)  # Output: 0
            

🧩 Python Modules

A module is just a Python file (.py) containing functions, classes, or variables.

Python has a large standard library, which includes many useful modules (like math, os, sys, etc.)

  # Import math Module
  import math

  # Return factorial of a number
  print(math.factorial(5))
            

🧩 Create a Module in Python

To create a module just save the Python code you want in a file with the file extension .py

Filename: my_module.py

  # my_module.py

  message = "Welcome to Python Modules!"  # Variable

  def greet(name):  # Function
      return f"Hello, {name}!"
            

🧩 Use a Module in Python

Filename: main.py

  # main.py

  import my_module  # Import the custom module

  print(my_module.message)  # Access variable ✅
  print(my_module.greet("Deepak"))  # Call function ✅
            

🧩 Types of Import in Python

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