python 类方法的装饰器

Question

我有一个装饰器来注册一些类方法。如何正确获取 self 和 run 参数？

class Task(object):
    _tasks = []

    @staticmethod
    def register(name):
        def decorator(fn):
            @wraps(fn)
            def wrapper(self=None, run=True, *args, **kwargs):
                if not run:
                    task = defaultdict()
                    task['name'] = name
                    task['fn'] = getattr(self, fn.__name__, None)
                    task['obj'] = self
                    task['args'] = deepcopy(args)
                    task['kwargs'] = deepcopy(kwargs)
                    Task._tasks.append(task)
                else:
                    return fn(self, *args, **kwargs)
            return wrapper
        return decorator

class Test(object):
    def __init__(self, name):
        self.name = name

    @Task.register('foo')
    def foo(self, v1, v2):
        print 'running foo in object {} with arguments {} {}'.format(self.name, v1, v2)

    @Task.register('hello')
    def hello(self):
        print 'running hello in object {} '.format(self.name)

    def load(self):
        self.foo('1', '2', run=False)
        self.hello(run=False)

t1=Test('t1')
t1.load()

出现以下错误:

Traceback (most recent call last):

    TypeError: wrapper() got multiple values for keyword argument 'run'

Answer 1

您的问题与装饰器无关。您的代码实际上执行与此相同的操作:

def foo(run=False, *args, **kwargs):
    print(run, args, kwargs)

foo(1, 2, run=True)  # TypeError: foo() got multiple values for argument 'run'

根据函数的签名，Python 将尝试设置 run=1、args = (2,)，然后遇到 TypeError .

一个修复 - 虽然不是一个很好的修复 - 可能是:

def foo(*args, **kwargs):
    run = kwargs.pop('run', False)  # run defaults to False; remove from kwargs
    print(run, args, kwargs)