Python Scope — Full Detailed Notes

What is Scope?

Understanding scope helps you control variable access and avoid conflicts between local and global names.

Local Scope

A variable inside a function exists only within that function.

def myfunc():
  x = 300
  print(x)

myfunc()

Local Scope inside Inner Functions

Inner functions can access variables from their parent function.

def myfunc():
  x = 300
  def myinnerfunc():
    print(x)
  myinnerfunc()

myfunc()

Global Scope

A variable created outside any function belongs to the global scope and can be accessed anywhere.

x = 300

def myfunc():
  print(x)

myfunc()
print(x)

Same Variable Name (Local vs Global)

Local and global variables with the same name are treated separately.

x = 300

def myfunc():
  x = 200
  print(x)

myfunc()
print(x)

The global Keyword

Use global to make a variable inside a function become global.

Create Global Variable

def myfunc():
  global x
  x = 300

myfunc()
print(x)

Modify Global Variable

x = 300

def myfunc():
  global x
  x = 200

myfunc()
print(x)

The nonlocal Keyword

nonlocal lets you modify variables from an enclosing (outer) function within a nested function.

def myfunc1():
  x = "Jane"
  def myfunc2():
    nonlocal x
    x = "hello"
  myfunc2()
  return x

print(myfunc1())

The LEGB Rule

Python searches variables in the order:

• L – Local
• E – Enclosing
• G – Global
• B – Built-in

Example

x = "global"

def outer():
  x = "enclosing"
  def inner():
    x = "local"
    print("Inner:", x)
  inner()
  print("Outer:", x)

outer()
print("Global:", x)

Summary

Mastering scope prevents name conflicts and helps write clean, maintainable code.