相关疑难解决方法(0)

我想使用一个接受一个参数的装饰器,检查该参数是否为None,如果是True则让装饰函数运行.

我想在类定义中使用这个装饰器,因为我有一组类方法,它们首先检查特定的类变量是否为None.我认为如果我使用装饰器会更好看.

我想做这样的事情:

# decorator
def variable_tester(arg):
    def wrap(f):
        def wrapped_f(*args):
            if arg is not None:
                f(*args)
            else:
                pass
        return wrapped_f
    return wrap

# class definition  
class my_class(object):
    def __init__(self):
        self.var = None

    @variable_tester(self.var) # This is wrong. How to pass self.var to decorator?
    def printout(self):
        print self.var

    def setvar(self, v):
        self.var = v

# testing code
my_instance = my_class()
my_instance.printout() # It should print nothing

my_instance.setvar('foobar')
my_instance.printout() # It should print foobar