Scope of Variables in Functions

Variable scope dictates where a variable can be read or modified in a Python program.

Key Concepts & Detailed Explanation

The LEGB Rule for variable lookup:

1. 1
   L (Local): Defined inside the current function.
2. 2
   E (Enclosing): Defined in enclosing outer functions.
3. 3
   G (Global): Defined at top-level module scope.
4. 4
   B (Built-in): Built-in Python functions and constants (e.g. print, len).

Use the 'global' keyword to modify global variables from inside a function, and 'nonlocal' for enclosing scopes.

Code Examples & Output

Expected Output:

Best Practices & Common Pitfalls

Minimizing reliance on global variables makes code modular, testable, and thread-safe.

Practice Quiz

1. What does the LEGB acronym stand for in Python variable resolution?

• A) Local, Enclosing, Global, Built-in
• B) Logical, External, General, Binary
• C) Linear, Execution, Grid, Block
• D) Loop, Engine, Global, Base

2. Which keyword allows modifying an outer function's variable from an inner closure?

• A) global
• B) nonlocal
• C) outer
• D) super

Practice Challenge

Create an outer function 'counter()' returning an inner function that increments a nonlocal count variable on each call.