What is a decorator?

Decorator is a design pattern that allows adding new behavior to an object dynamically without changing its structure.

Main characteristics:

• Flexibility: Allows adding or removing functionality of objects at runtime.
• Independence: New functionality can be added independently of the main class.
• Use of composition: The decorator contains a reference to the decorated object and forwards requests to it, adding some logic before or after execution.

Applications:

• Logging
• Access control (authentication/authorization)
• Adding metadata
• Changing method behavior

Example in Python:

# Simple function for decoration
def my_function():
    return "Hello"

# Decorator
def simple_decorator(func):
    def wrapper():
        print("Before function call")
        result = func()
        print("After function call")
        return result
    return wrapper

# Applying the decorator
@simple_decorator
def decorated_function():
    return "World"

# Calling the decorated function
# decorated_function() would output:
# Before function call
# After function call
# and return "World"