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Python - Decorators

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Decorators

Code Properties

  • Language: Python
  • Concept: Metaprogramming

Overview

Decorators are functions that modify the behavior of other functions. They allow you to add functionality without changing the original function code - like adding superpowers to your functions.

Key benefits:

  • Eliminate repetitive boilerplate code
  • Add cross-cutting concerns (timing, logging, caching)
  • Keep functions focused on their core purpose

Code

Timer Decorator

def my_timer(func):
    """Decorator to time function execution."""
    import time
    def wrapper(*args, **kwargs):
        start = time.time()
        result = func(*args, **kwargs)
        end = time.time()
        print(f"{func.__name__} took: {end-start:.4f} seconds")
        return result
    return wrapper
 
@my_timer
def slow_function(n):
    import time
    time.sleep(n)

Logging Decorator

def log_calls(func):
    """Decorator to log function calls."""
    def wrapper(*args, **kwargs):
        print(f"Calling {func.__name__} with {args}, {kwargs}")
        result = func(*args, **kwargs)
        print(f"{func.__name__} returned {result}")
        return result
    return wrapper
 
@log_calls
def add(a, b):
    return a + b

Usage

# the decorator is applied with @ syntax
@my_timer
def process_data(data):
    # function implementation
    pass
 
# equivalent to:
def process_data(data):
    pass
process_data = my_timer(process_data)

Tip

Decorators are powerful but use them wisely. Too many stacked decorators make code harder to understand.

Appendix

Note created on 2024-04-15 and last modified on 2024-12-31.

See Also

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