Python functools 模块，singledispatch() 实例源码

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def dispatch(method: Callable[[Any, Type[T], Mapping[str, Any], PipelineContext], Any]) -> Callable[[Any, Type[T], Mapping[str, Any], PipelineContext], Any]:
        dispatcher = singledispatch(method)
        provides = set()

        def wrapper(self: Any, type: Type[T], query: Mapping[str, Any], context: PipelineContext = None) -> Any:
            call = dispatcher.dispatch(type)
            try:
                return call(self, query, context=context)
            except TypeError:
                raise DataSource.unsupported(type)

        def register(type: Type[T]) -> Callable[[Any, Type[T], Mapping[str, Any], PipelineContext], Any]:
            provides.add(type)
            return dispatcher.register(type)

        wrapper.register = register
        wrapper._provides = provides
        update_wrapper(wrapper, method)
        return wrapper

def dispatch(method: Callable[[Any, Type[T], Any, PipelineContext], None]) -> Callable[[Any, Type[T], Any, PipelineContext], None]:
        dispatcher = singledispatch(method)
        accepts = set()

        def wrapper(self: Any, type: Type[T], items: Any, context: PipelineContext = None) -> None:
            call = dispatcher.dispatch(type)
            try:
                return call(self, items, context=context)
            except TypeError:
                raise DataSink.unsupported(type)

        def register(type: Type[T]) -> Callable[[Any, Type[T], Any, PipelineContext], None]:
            accepts.add(type)
            return dispatcher.register(type)

        wrapper.register = register
        wrapper._accepts = accepts
        update_wrapper(wrapper, method)
        return wrapper

def dispatch(method: Callable[[Any, Type[T], F, PipelineContext], T]) -> Callable[[Any, Type[T], F, PipelineContext], T]:
        dispatcher = singledispatch(method)
        transforms = {}

        def wrapper(self: Any, target_type: Type[T], value: F, context: PipelineContext = None) -> T:
            call = dispatcher.dispatch(TypePair[value.__class__, target_type])
            try:
                return call(self, value, context=context)
            except TypeError:
                raise DataTransformer.unsupported(target_type, value)

        def register(from_type: Type[F], to_type: Type[T]) -> Callable[[Any, Type[T], F, PipelineContext], T]:
            try:
                target_types = transforms[from_type]
            except KeyError:
                target_types = set()
                transforms[from_type] = target_types
            target_types.add(to_type)

            return dispatcher.register(TypePair[from_type, to_type])

        wrapper.register = register
        wrapper._transforms = transforms
        update_wrapper(wrapper, method)
        return wrapper

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def import_single_dispatch():
    try:
        from functools import singledispatch
    except ImportError:
        singledispatch = None

    if not singledispatch:
        try:
            from singledispatch import singledispatch
        except ImportError:
            pass

    if not singledispatch:
        raise Exception(
            "It seems your python version does not include "
            "functools.singledispatch. Please install the 'singledispatch' "
            "package. More information here: "
            "https://pypi.python.org/pypi/singledispatch"
        )

    return singledispatch

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled separately
    # via Multi().
    if isinstance(yielded, (list, dict)):
        return multi_future(yielded)
    elif is_future(yielded):
        return yielded
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled separately
    # via Multi().
    if isinstance(yielded, (list, dict)):
        return multi_future(yielded)
    elif is_future(yielded):
        return yielded
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def test_mro(self):
        @functools.singledispatch
        def g(obj):
            return "base"
        class A:
            pass
        class C(A):
            pass
        class B(A):
            pass
        class D(C, B):
            pass
        def g_A(a):
            return "A"
        def g_B(b):
            return "B"
        g.register(A, g_A)
        g.register(B, g_B)
        self.assertEqual(g(A()), "A")
        self.assertEqual(g(B()), "B")
        self.assertEqual(g(C()), "A")
        self.assertEqual(g(D()), "B")

def test_c_classes(self):
        @functools.singledispatch
        def g(obj):
            return "base"
        @g.register(decimal.DecimalException)
        def _(obj):
            return obj.args
        subn = decimal.Subnormal("Exponent < Emin")
        rnd = decimal.Rounded("Number got rounded")
        self.assertEqual(g(subn), ("Exponent < Emin",))
        self.assertEqual(g(rnd), ("Number got rounded",))
        @g.register(decimal.Subnormal)
        def _(obj):
            return "Too small to care."
        self.assertEqual(g(subn), "Too small to care.")
        self.assertEqual(g(rnd), ("Number got rounded",))

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def test_mro(self):
        @functools.singledispatch
        def g(obj):
            return "base"
        class A:
            pass
        class C(A):
            pass
        class B(A):
            pass
        class D(C, B):
            pass
        def g_A(a):
            return "A"
        def g_B(b):
            return "B"
        g.register(A, g_A)
        g.register(B, g_B)
        self.assertEqual(g(A()), "A")
        self.assertEqual(g(B()), "B")
        self.assertEqual(g(C()), "A")
        self.assertEqual(g(D()), "B")

def test_c_classes(self):
        @functools.singledispatch
        def g(obj):
            return "base"
        @g.register(decimal.DecimalException)
        def _(obj):
            return obj.args
        subn = decimal.Subnormal("Exponent < Emin")
        rnd = decimal.Rounded("Number got rounded")
        self.assertEqual(g(subn), ("Exponent < Emin",))
        self.assertEqual(g(rnd), ("Number got rounded",))
        @g.register(decimal.Subnormal)
        def _(obj):
            return "Too small to care."
        self.assertEqual(g(subn), "Too small to care.")
        self.assertEqual(g(rnd), ("Number got rounded",))

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def convert_yielded(yielded):
    """Convert a yielded object into a `.Future`.

    The default implementation accepts lists, dictionaries, and Futures.

    If the `~functools.singledispatch` library is available, this function
    may be extended to support additional types. For example::

        @convert_yielded.register(asyncio.Future)
        def _(asyncio_future):
            return tornado.platform.asyncio.to_tornado_future(asyncio_future)

    .. versionadded:: 4.1
    """
    # Lists and dicts containing YieldPoints were handled earlier.
    if isinstance(yielded, (list, dict)):
        return multi(yielded)
    elif is_future(yielded):
        return yielded
    elif isawaitable(yielded):
        return _wrap_awaitable(yielded)
    else:
        raise BadYieldError("yielded unknown object %r" % (yielded,))

def singledispatch_pipeverb(func):
    """
    Convenience decorator to convert a function to a singledispatch pipeline verb

    The function is converted to a :func:`singledispatch` function and then
    converted into an instance of class :class:`PipeVerb` via :func:`pipeverb`.

    This decorator is equivalent to ``verb = pipeverb(singledispatch(func))``

    Please see :func:`pipeverb` for rules which a pipeline verb has to follow!

    :param func: the function which should be converted
    :type func: function
    :return: PipeVerb instance which can be used in rshift `>>` operations
    :rtype: PipeVerb

    :Example:

    >>> @singledispatch_pipeverb
    >>> def my_verb_impl(input, x=1, y=2):
    >>>     raise NotImplementedError("my_verb is not implemented for data of type %s" % type(input))
    >>> @my_verb_impl.register(pd.DataFrame)
    >>> def my_verb_impl_df(input, x=1, y=2):
    >>>     # do something with input being a Dataframe
    >>>     pass
    >>> # ensure that pd.DataFrame is useable as a pipe source
    >>> make_pipesource(pd.DataFrame)


    .. seealso:: :func:`pipeverb`, :func:`singledispatch`
    """
    return pipeverb(singledispatch(func))

def method_dispatch(func: Callable[..., T]) -> Callable[..., T]:
    """
    Single-dispatch class method decorator
    Works like functools.singledispatch for none-static class methods.
    """
    dispatcher = functools.singledispatch(func)

    @functools.wraps(func)
    def wrapper(*args: Any, **_: Any) -> T:
        return dispatcher.dispatch(args[1].__class__)(*args, **_)

    # issue: https://github.com/python/mypy/issues/708
    wrapper.register = dispatcher.register  # type: ignore
    return wrapper

def test_simple_overloads(self):
        @functools.singledispatch
        def g(obj):
            return "base"
        def g_int(i):
            return "integer"
        g.register(int, g_int)
        self.assertEqual(g("str"), "base")
        self.assertEqual(g(1), "integer")
        self.assertEqual(g([1,2,3]), "base")

def test_register_decorator(self):
        @functools.singledispatch
        def g(obj):
            return "base"
        @g.register(int)
        def g_int(i):
            return "int %s" % (i,)
        self.assertEqual(g(""), "base")
        self.assertEqual(g(12), "int 12")
        self.assertIs(g.dispatch(int), g_int)
        self.assertIs(g.dispatch(object), g.dispatch(str))
        # Note: in the assert above this is not g.
        # @singledispatch returns the wrapper.

def test_wrapping_attributes(self):
        @functools.singledispatch
        def g(obj):
            "Simple test"
            return "Test"
        self.assertEqual(g.__name__, "g")
        if sys.flags.optimize < 2:
            self.assertEqual(g.__doc__, "Simple test")

def has_context(incorrect_msg=None, exact_names=False, state=None):
    # call _has_context, since the built-in singledispatch can only use 1st pos arg
    return _has_context(state, incorrect_msg, exact_names)

def test_simple_overloads(self):
        @functools.singledispatch
        def g(obj):
            return "base"
        def g_int(i):
            return "integer"
        g.register(int, g_int)
        self.assertEqual(g("str"), "base")
        self.assertEqual(g(1), "integer")
        self.assertEqual(g([1,2,3]), "base")

def test_register_decorator(self):
        @functools.singledispatch
        def g(obj):
            return "base"
        @g.register(int)
        def g_int(i):
            return "int %s" % (i,)
        self.assertEqual(g(""), "base")
        self.assertEqual(g(12), "int 12")
        self.assertIs(g.dispatch(int), g_int)
        self.assertIs(g.dispatch(object), g.dispatch(str))
        # Note: in the assert above this is not g.
        # @singledispatch returns the wrapper.

def test_wrapping_attributes(self):
        @functools.singledispatch
        def g(obj):
            "Simple test"
            return "Test"
        self.assertEqual(g.__name__, "g")
        if sys.flags.optimize < 2:
            self.assertEqual(g.__doc__, "Simple test")