backports_abc.py 文件源码

def mk_coroutine():
    from abc import abstractmethod

    class Coroutine(Awaitable):
        __slots__ = ()

        @abstractmethod
        def send(self, value):
            """Send a value into the coroutine.
            Return next yielded value or raise StopIteration.
            """
            raise StopIteration

        @abstractmethod
        def throw(self, typ, val=None, tb=None):
            """Raise an exception in the coroutine.
            Return next yielded value or raise StopIteration.
            """
            if val is None:
                if tb is None:
                    raise typ
                val = typ()
            if tb is not None:
                val = val.with_traceback(tb)
            raise val

        def close(self):
            """Raise GeneratorExit inside coroutine.
            """
            try:
                self.throw(GeneratorExit)
            except (GeneratorExit, StopIteration):
                pass
            else:
                raise RuntimeError('coroutine ignored GeneratorExit')

        @classmethod
        def __subclasshook__(cls, C):
            if cls is Coroutine:
                mro = C.__mro__
                for method in ('__await__', 'send', 'throw', 'close'):
                    for base in mro:
                        if method in base.__dict__:
                            break
                    else:
                        return NotImplemented
                return True
            return NotImplemented

    return Coroutine


###
#  make all ABCs available in this module