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Building Python Decorators

Advanced Abstractions

Decorators for Cross-Cutting Concerns

Decorators wrap functions or methods to add behavior (logging, auth, retries) without scattering boilerplate.

Use functools.wrapsWrite parameterized decorators

Basic decorator​

from functools import wraps

def log_calls(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        logger.info('Calling %s', func.__name__)
        return func(*args, **kwargs)
    return wrapper

@log_calls
def process(order_id): ...
  • Always use @wraps to preserve metadata (docstring, name, annotations).

Parameterized decorator​

def retry(times=3):
    def decorator(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            ...
        return wrapper
    return decorator
  • The outer function captures configuration.

Decorating methods & classes​

  • Methods receive self as the first argument; decorators work the same.
  • Class decorators can inject behavior or registration hooks.

Next up in your learning path

functools

Reuse partial, lru_cache, and wraps for DRY decorators.

Companion

Context managers

Pair decorators with `with` blocks for resource management.

Next topic

Error handling cluster

Wrap functions to standardize exception handling.

Practical