1. 基本裝飾器
1.1. 無參方法無參裝飾器
# 無參log裝飾器
def log(func):
def wrapper():
print('Log: excute method {}()'.format(func.__name__))
return func()
return wrapper
# 無參方法
@log
def do_save():
print('save something!')
# Log: excute method do_save()
# save something!
do_save()
1.2. 有參方法無參裝飾器
利用(*args, **kwargs)來表示任意參數。
此時若@log則會出現異常，因為@log裝飾器的實現中并沒有接收參數。
# 無參裝飾器
def log_new(func):
def wrapper(*args, **kwargs):
print('Log: excute method {}()'.format(func.__name__))
return func(*args, **kwargs)
return wrapper
# 帶參數的方法
# @log # TypeError need 1 argument
@log_new
def do_save_user(user):
print('save {}'.format(user))
# Log: excute method do_save_user()
# save JiangW
do_save_user('JiangW')
1.3. 有參方法有參裝飾器
# 帶參數的裝飾器
def log_level(level):
def decorator(func):
def wrapper(*args, **kwargs):
print('Log[{}]: excute method {}()'.format(level, func.__name__))
return func(*args, **kwargs)
return wrapper
return decorator
@log_level('INFO')
def do_delete_user(user):
print('delete {}'.format(user))
# Log[INFO]: excute method do_delete_user()
# delete JiangW
do_delete_user('JiangW')
2. 基于類實現的裝飾器
2.1. 簡單基于類實現的裝飾器
# 帶參數
class LoggingLevel(object):
def __init__(self, level):
self.level = level
def __call__(self, func):
def wrapper(*args, **kwargs):
print('Log[{}]: excute method {}()'.format(self.level, func.__name__))
return func(*args, **kwargs)
return wrapper
@LoggingLevel('WARN')
def do_remove_user(user):
print('remove {}'.format(user))
# Log[WARN]: excute method do_remove_user()
# remove JiangW
do_remove_user('JiangW')
3. 注意事項
3.1. 拆分裝飾器
利用@log_level語法糖來實現的裝飾器。
def log_level(level):
def decorator(func):
def wrapper(*args, **kwargs):
print('Log[{}]: excute method {}()'.format(level, func.__name__))
return func(*args, **kwargs)
return wrapper
return decorator
@log_level('INFO')
def do_delete_user(user):
print('delete {}'.format(user))
# Log[INFO]: excute method do_delete_user()
# delete JiangW
do_delete_user('JiangW')
拆分成每一步實際上最終為:
# 等同于
def do_delete_user(user):
print('delete {}'.format(user))
# # Log[INFO]: excute method do_delete_user()
# delete JiangW
decorator = log_level('INFO')
wrapper = decorator(do_delete_user)
wrapper('Jian111gW')
3.2. 函數名稱改變
如3.1所述拆分裝飾器后實際上最終是調用了
wrapper = decorator(do_delete_user)
wrapper('Jian111gW')
此時被@log_level裝飾器裝飾的函數名已經變成了wrapper
print(do_delete_user.__name__) # wrapper
利用functools.wraps來修正
def log_level(level):
def decorator(func):
@wraps(func)
def wrapper(*args, **kwargs):
print('Log[{}]: excute method {}()'.format(level, func.__name__))
return func(*args, **kwargs)
return wrapper
return decorator
@log_level('INFO')
def do_delete_user(user):
print('delete {}'.format(user))
print(do_delete_user.__name__) # do_delete_user
此時do_delete_user.__name__為do_delete_user.
