访问基 class 函数装饰器中的派生 class 属性

Access derived class attribute in base class function decorator

我想做类似的事情:

class A(Resource):
  @dec(from_file=A.docpath)
  def get(self):
     pass

class B(A):
  docpath = './docs/doc_for_get_b.json'

class C(A):
  docpath = './docs/doc_for_get_c.json'

def dec(*args, **kwargs):
    def inner(f):
       docpath = kwargs.get('from_file')
       f.__kwargs__ = open(path, 'r').read()
       return f
    return inner

将调用的函数是 B.getC.get,从不调用 A.get

如何访问class Bclass C中定义的自定义属性docpath并将其传递给class Aget函数的装饰器?

当前解决方案:将装饰器放在每个派生 class ...

class A(Resource):
  def _get(self):
     pass

class B(A):
  @dec(from_file='./docs/doc_for_get_b.json')
  def get(self):
     return self._get()

class C(A)
  @dec(from_file='./docs/doc_for_get_c.json')
  def get(self):
     return self._get()

这行得通,但与前面代码中 classes 的单行声明相比,它非常难看。

要在装饰器中访问 class 的属性很容易:

def decorator(function):

    def inner(self):
        self_type = type(self)
        # self_type is now the class of the instance of the method that this
        # decorator is wrapping
        print('The class attribute docpath is %r' % self_type.docpath)

        # need to pass self through because at the point function is
        # decorated it has not been bound to an instance, and so it is just a
        # normal function which takes self as the first argument.
        function(self)

    return inner


class A:
    docpath = "A's docpath"

    @decorator
    def a_method(self):
        print('a_method')


class B(A):
    docpath = "B's docpath"

a = A()
a.a_method()

b = B()
b.a_method()

一般来说,我发现使用了多级装饰器,即创建装饰器的装饰器工厂函数,例如您使用过的,例如:

def decorator_factory(**kwargs):

    def decorator_function(function):

        def wrapper(self):

            print('Wrapping function %s with kwargs %s' % (function.__name__, kwargs))
            function(self)

        return wrapper

    return decorator_function


class A:

    @decorator_factory(a=2, b=3)
    def do_something(self):
        print('do_something')

a = A()
a.do_something()

阅读代码时很难正确理解,所以我会错误地使用 class 属性和通用的 superclass 方法来支持大量装饰器。

所以在你的情况下,不要将文件路径作为参数传递给装饰器工厂,而是将其设置为派生的 classes 上的 class 属性,然后编写superclass 中的一个通用方法,它从实例的 class.

中读取 class 属性