from functools import wraps
def intercept(target,**trigger):
def decorator(func):
names = getattr(func,'_names',None)
if names is None:
code = func.func_code
names = code.co_varnames[:code.co_argcount]
@wraps(func)
def decorated(*args,**kwargs):
all_args = kwargs.copy()
for n,v in zip(names,args):
all_args[n] = v
for k,v in trigger.iteritems():
if k in all_args and all_args[k] != v:
break
else:
return target(all_args)
return func(*args,**kwargs)
decorated._names = names
return decorated
return decorator
例子:
def interceptor1(kwargs):
print 'Intercepted by #1!'
def interceptor2(kwargs):
print 'Intercepted by #2!'
def interceptor3(kwargs):
print 'Intercepted by #3!'
@intercept(interceptor1,arg1=20,arg2=5) # if arg1 == 20 and arg2 == 5
@intercept(interceptor2,arg1=20) # elif arg1 == 20
@intercept(interceptor3,arg2=5) # elif arg2 == 5
def foo(arg1,arg2):
return arg1+arg2
>>> foo(3,4)
7
>>> foo(20,4)
Intercepted by #2!
>>> foo(3,5)
Intercepted by #3!
>>> foo(20,5)
Intercepted by #1!
>>>
functools.wraps
做 wiki 上的“简单装饰器”所做的事情;更新__doc__
,__name__
以及装饰器的其他属性。