Python Decorators

1. What is a Decorator?

A decorator is a function that adds extra work to another function.

In simple words:
👉 A decorator wraps a function
👉 It runs before or after the function
👉 It does not change the original function code

2. Real-Life Example

Think of a gift box 🎁

• Gift = function

• Wrapper paper = decorator

Decorator adds something extra around the function.

3. Why Use Decorators?

Decorators help us to:
✔ Add logging
✔ Add security (login check)
✔ Measure time
✔ Reuse code

4. Function Without Decorator

Example

5. Simple Decorator Example

Step 1: Create Decorator

Step 2: Use Decorator

Output:

6. How @ Works?

This is same as:

7. Decorator with Arguments

Example

8. Decorator with Multiple Arguments

Example

9. Real Use Example (Login Check)

Example

10. Using functools.wraps (Good Practice)

This keeps function name and info.

Example

11. Common Beginner Mistakes

❌ Forgetting to Call Function Inside Wrapper

✔ Correct:

❌ Not Returning Wrapper

❌ Wrong.

12. Simple Practice Examples

Example 1: Time Logger

Example 2: Math Decorator

Example 3: Decorator Without @

13. Summary (Python Decorators)

✔ Decorators add extra behavior
✔ Use @decorator_name
✔ Wrapper function is important
✔ Supports arguments
✔ Very powerful Python feature

📘 Perfect for Beginner & Advanced eBook

This chapter is ideal for:

• Python learners

• Interview preparation

• Real-world projects

• Clean code writing

If you want next, I can write:

• Advanced Decorators

• Class Decorators

• Generators vs Decorators

• Real Python Projects

Just tell me 😊