为方法跳过“self”的Decorator

一种解决方案是以某种方式检测修饰函数是否是类方法,如果不是不可能的话(据我所知),很难做到干净。这个 inspect ismethod() 和 isfunction() 不要在类定义中使用的装饰器中工作。

考虑到这一点,这里有一种有点黑客的方法来检查修饰的callable的第一个参数是否被命名为 "self" ,这是它在类方法中的编码约定(尽管 ,所以 caveat emptor

下面的代码似乎可以在python2和python3中使用。但是在python3中,它可能会 DeprecationWarning 取决于所使用的子版本,所以它们在下面的代码部分中被抑制了。

from functools import wraps
import inspect
import warnings

def validate_url(f):
    @wraps(f)
    def validated(*args, **kwargs):
        with warnings.catch_warnings():
            # Suppress DeprecationWarnings in this section.
            warnings.simplefilter('ignore', category=DeprecationWarning)

            # If "f"'s first argument is named "self",
            # assume it's a method.
            if inspect.getargspec(f).args[0] == 'self':
                url = args[1]
            else:  # Otherwise assume "f" is a ordinary function.
                url = args[0]
        print('testing url: {!r}'.format(url))
        assert len(url.split('.')) == 3  # Trivial "validation".
        return f(*args, **kwargs)
    return validated

@validate_url
def some_func(url, some_other_arg, *some_args, **some_kwargs):
    print('some_func() called')


class SomeClass:
    @validate_url
    def some_method(self, url, some_other_args):
        print('some_method() called')


if __name__ == '__main__':
    print('** Testing decorated function **')
    some_func('xxx.yyy.zzz', 'another arg')
    print('  URL OK')
    try:
        some_func('https://bogus_url.com', 'another thing')
    except AssertionError:
        print('  INVALID URL!')

    print('\n** Testing decorated method **')
    instance = SomeClass()
    instance.some_method('aaa.bbb.ccc', 'something else')  # -> AssertionError
    print('  URL OK')
    try:
        instance.some_method('foo.bar', 'arg 2')  # -> AssertionError
    except AssertionError:
        print('  INVALID URL!')

** Testing decorated function **
testing url: 'xxx.yyy.zzz'
some_func() called
  URL OK
testing url: 'https://bogus_url.com'
  INVALID URL!

** Testing decorated method **
testing url: 'aaa.bbb.ccc'
some_method() called
  URL OK
testing url: 'foo.bar'
  INVALID URL!