一种自顶而下的Python装饰器设计方法

@decorator
def func(*args, **kwargs):
    do_something()

>>> func(a, b, c='value')
# 等价于
>>> decorated_func = decorator(func)
>>> decorated_func(a, b, c='value')

@timethis
def fun(*args, **kwargs):
    pass

>>> func(*args, **kwargs)
# 等价于
>>> decorated_func = timethis(func)
>>> decorated_func(a, b, c='value')

def timethis(func):
    def wrapper(*args, **kwargs):
        pass

    return wrapper

def timethis(func):
    def wrapper(*args, **kwargs):
        result = func(*args, **kwargs)
        return result
    return wrapper

import time

def timethis(func):
    def wrapper(*args, **kwargs):
        start = time.time()
        result = func(*args, **kwargs)
        end = time.time()
        print(func.__name__, end-start)
        return result
    return wrapper

@timethis
def fibonacci(n):
    """
    求斐波拉契数列第 n 项的值
    """
    a = b = 1
    while n > 2:
        a, b = b, a + b
        n -= 1
    return b

>>> fibonacci(10000)
fibonacci 0.004000663757324219
...结果太大省略

>>> fibonacci.__name__
wrapper
>>> fibonacci.__doc__
None

from functools import wraps
import time

def timethis(func):
    @wraps(func)
    def wrapper(*args, **kwargs):
        start = time.time()
        result = func(*args, **kwargs)
        end = time.time()
        print(func.__name__, end - start)
        return result

    return wrapper

@logged('debug', name='example', message='message')
def fun(*args, **kwargs):
    pass

>>> func(a, b, c='value')
# 等价于
>>> decorator = logged('debug', name='example', message='message')
>>> decorated_func = decorator(func)
>>> decorated_func(a, b, c='value')

def logged(level, name=None, message=None):
    def decorator(func):
        @wraps(func)
        def wrapper(*args, **kwargs):
            pass
        return wrapper
    return decorator

from functools import wraps

def logged(level, name=None, message=None):
    def decorator(func):
        logname = name if name else func.__module__
        logmsg = message if message else func.__name__

        @wraps(func)
        def wrapper(*args, **kwargs):
            print(level, logname, logmsg, sep=' - ')
            return func(*args, **kwargs)
        return wrapper
    return decorator

@logged
def func(*args, **kwargs):
    pass

@logged(level='debug', name='example', message='message')
def fun(*args, **kwargs):
    pass

# 使用 @logged 直接装饰
>>> func(a, b, c='value')
# 等价于
>>> decorated_func = logged(func)
>>> decorated_func(a, b, c='value')

# 使用 @logged(level='debug', name='example', message='message') 装饰
>>> func(a, b, c='value')
# 等价于
>>> decorator = logged(level='debug', name='example', message='message')
>>> decorated_func = decorator(func)
>>> decorated_func(a, b, c='value')

from functools import wraps, partial

def logged(func=None, *, level='debug', name=None, message=None):
    if func is None:
        return partial(logged, level=level, name=name, message=message)

    logname = name if name else func.__module__
    logmsg = message if message else func.__name__

    @wraps(func)
    def wrapper(*args, **kwargs):
        print(level, logname, logmsg, sep=' - ')
        return func(*args, **kwargs)
    return wrapper

from functools import wraps

def retry(times, traced_exceptions=None, reraise_exception=None):
    def decorator(func):

        @wraps(func)
        def wrapper(*args, **kwargs):
            n = times
            trace_all = traced_exceptions is None
            trace_specified = traced_exceptions is not None
            while True:
                try:
                    return func(*args, **kwargs)
                except Exception as e:
                    traced = trace_specified and isinstance(e, traced_exceptions)
                    reach_limit = n == 0

                    if not (trace_all or traced) or reach_limit:
                        if reraise_exception is not None:
                            raise reraise_exception
                        raise
                    n -= 1
        return wrapper
    return decorator