Python types.coroutine() Examples

def test_func_4(self):
        async def foo():
            raise StopIteration

        check = lambda: self.assertRaisesRegex(
            TypeError, "'coroutine' object is not iterable")

        with check():
            list(foo())

        with check():
            tuple(foo())

        with check():
            sum(foo())

        with check():
            iter(foo())

        with silence_coro_gc(), check():
            for i in foo():
                pass

        with silence_coro_gc(), check():
            [i for i in foo()] 

def sleep(duration):
    """Return a `.Future` that resolves after the given number of seconds.

    When used with ``yield`` in a coroutine, this is a non-blocking
    analogue to `time.sleep` (which should not be used in coroutines
    because it is blocking)::

        yield gen.sleep(0.5)

    Note that calling this function on its own does nothing; you must
    wait on the `.Future` it returns (usually by yielding it).

    .. versionadded:: 4.1
    """
    f = Future()
    IOLoop.current().call_later(duration, lambda: f.set_result(None))
    return f 

def _argument_adapter(callback):
    """Returns a function that when invoked runs ``callback`` with one arg.

    If the function returned by this function is called with exactly
    one argument, that argument is passed to ``callback``.  Otherwise
    the args tuple and kwargs dict are wrapped in an `Arguments` object.
    """
    def wrapper(*args, **kwargs):
        if kwargs or len(args) > 1:
            callback(Arguments(args, kwargs))
        elif args:
            callback(args[0])
        else:
            callback(None)
    return wrapper

# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded. 

def run_coroutine_threadsafe(coro, loop):
    """Submit a coroutine object to a given event loop.

    Return a concurrent.futures.Future to access the result.
    """
    if not coroutines.iscoroutine(coro):
        raise TypeError('A coroutine object is required')
    future = concurrent.futures.Future()

    def callback():
        try:
            futures._chain_future(ensure_future(coro, loop=loop), future)
        except Exception as exc:
            if future.set_running_or_notify_cancel():
                future.set_exception(exc)
            raise

    loop.call_soon_threadsafe(callback)
    return future


# WeakSet containing all alive tasks. 

def test_set_wrapper_4(self):
        @types.coroutine
        def foo():
            return 'spam'

        wrapped = None
        def wrap(gen):
            nonlocal wrapped
            wrapped = gen
            return gen

        sys.set_coroutine_wrapper(wrap)
        try:
            foo()
            self.assertIs(
                wrapped, None,
                "generator-based coroutine was wrapped via "
                "sys.set_coroutine_wrapper")
        finally:
            sys.set_coroutine_wrapper(None) 

def ensure_future(coro_or_future, *, loop=None):
    """Wrap a coroutine or an awaitable in a future.

    If the argument is a Future, it is returned directly.
    """
    if coroutines.iscoroutine(coro_or_future):
        if loop is None:
            loop = events.get_event_loop()
        task = loop.create_task(coro_or_future)
        if task._source_traceback:
            del task._source_traceback[-1]
        return task
    elif futures.isfuture(coro_or_future):
        if loop is not None and loop is not futures._get_loop(coro_or_future):
            raise ValueError('loop argument must agree with Future')
        return coro_or_future
    elif inspect.isawaitable(coro_or_future):
        return ensure_future(_wrap_awaitable(coro_or_future), loop=loop)
    else:
        raise TypeError('An asyncio.Future, a coroutine or an awaitable is '
                        'required') 

def test_non_gen_values(self):
        @types.coroutine
        def foo():
            return 'spam'
        self.assertEqual(foo(), 'spam')

        class Awaitable:
            def __await__(self):
                return ()
        aw = Awaitable()
        @types.coroutine
        def foo():
            return aw
        self.assertIs(aw, foo())

        # decorate foo second time
        foo = types.coroutine(foo)
        self.assertIs(aw, foo()) 

def _argument_adapter(callback):
    """Returns a function that when invoked runs ``callback`` with one arg.

    If the function returned by this function is called with exactly
    one argument, that argument is passed to ``callback``.  Otherwise
    the args tuple and kwargs dict are wrapped in an `Arguments` object.
    """
    def wrapper(*args, **kwargs):
        if kwargs or len(args) > 1:
            callback(Arguments(args, kwargs))
        elif args:
            callback(args[0])
        else:
            callback(None)
    return wrapper

# Convert Awaitables into Futures. It is unfortunately possible
# to have infinite recursion here if those Awaitables assume that
# we're using a different coroutine runner and yield objects
# we don't understand. If that happens, the solution is to
# register that runner's yieldable objects with convert_yielded. 

def _cancel_and_wait(fut, loop):
    """Cancel the *fut* future or task and wait until it completes."""

    waiter = loop.create_future()
    cb = functools.partial(_release_waiter, waiter)
    fut.add_done_callback(cb)

    try:
        fut.cancel()
        # We cannot wait on *fut* directly to make
        # sure _cancel_and_wait itself is reliably cancellable.
        await waiter
    finally:
        fut.remove_done_callback(cb)


# This is *not* a @coroutine!  It is just an iterator (yielding Futures). 

def __init__(self, gen, result_future, first_yielded):
        self.gen = gen
        self.result_future = result_future
        self.future = _null_future
        self.yield_point = None
        self.pending_callbacks = None
        self.results = None
        self.running = False
        self.finished = False
        self.had_exception = False
        self.io_loop = IOLoop.current()
        # For efficiency, we do not create a stack context until we
        # reach a YieldPoint (stack contexts are required for the historical
        # semantics of YieldPoints, but not for Futures).  When we have
        # done so, this field will be set and must be called at the end
        # of the coroutine.
        self.stack_context_deactivate = None
        if self.handle_yield(first_yielded):
            self.run() 

def test_set_wrapper_3(self):
        async def foo():
            return 'spam'

        def wrapper(coro):
            async def wrap(coro):
                return await coro
            return wrap(coro)

        sys.set_coroutine_wrapper(wrapper)
        try:
            with silence_coro_gc(), self.assertRaisesRegex(
                RuntimeError,
                "coroutine wrapper.*\.wrapper at 0x.*attempted to "
                "recursively wrap .* wrap .*"):

                foo()
        finally:
            sys.set_coroutine_wrapper(None) 

def get_stack(self, *, limit=None):
        """Return the list of stack frames for this task's coroutine.

        If the coroutine is not done, this returns the stack where it is
        suspended.  If the coroutine has completed successfully or was
        cancelled, this returns an empty list.  If the coroutine was
        terminated by an exception, this returns the list of traceback
        frames.

        The frames are always ordered from oldest to newest.

        The optional limit gives the maximum number of frames to
        return; by default all available frames are returned.  Its
        meaning differs depending on whether a stack or a traceback is
        returned: the newest frames of a stack are returned, but the
        oldest frames of a traceback are returned.  (This matches the
        behavior of the traceback module.)

        For reasons beyond our control, only one stack frame is
        returned for a suspended coroutine.
        """
        return base_tasks._task_get_stack(self, limit) 

def __init__(self, coro, *, loop=None):
        super().__init__(loop=loop)
        if self._source_traceback:
            del self._source_traceback[-1]
        if not coroutines.iscoroutine(coro):
            # raise after Future.__init__(), attrs are required for __del__
            # prevent logging for pending task in __del__
            self._log_destroy_pending = False
            raise TypeError(f"a coroutine was expected, got {coro!r}")

        self._must_cancel = False
        self._fut_waiter = None
        self._coro = coro
        self._context = contextvars.copy_context()

        self._loop.call_soon(self.__step, context=self._context)
        _register_task(self) 

def __init__(self, gen, result_future, first_yielded):
        self.gen = gen
        self.result_future = result_future
        self.future = _null_future
        self.yield_point = None
        self.pending_callbacks = None
        self.results = None
        self.running = False
        self.finished = False
        self.had_exception = False
        self.io_loop = IOLoop.current()
        # For efficiency, we do not create a stack context until we
        # reach a YieldPoint (stack contexts are required for the historical
        # semantics of YieldPoints, but not for Futures).  When we have
        # done so, this field will be set and must be called at the end
        # of the coroutine.
        self.stack_context_deactivate = None
        if self.handle_yield(first_yielded):
            gen = result_future = first_yielded = None
            self.run() 

def test_returning_itercoro(self):
        @types.coroutine
        def gen():
            yield

        gencoro = gen()

        @types.coroutine
        def foo():
            return gencoro

        self.assertIs(foo(), gencoro)

        # decorate foo second time
        foo = types.coroutine(foo)
        self.assertIs(foo(), gencoro) 

def __init__(self, gen, result_future, first_yielded):
        self.gen = gen
        self.result_future = result_future
        self.future = _null_future
        self.yield_point = None
        self.pending_callbacks = None
        self.results = None
        self.running = False
        self.finished = False
        self.had_exception = False
        self.io_loop = IOLoop.current()
        # For efficiency, we do not create a stack context until we
        # reach a YieldPoint (stack contexts are required for the historical
        # semantics of YieldPoints, but not for Futures).  When we have
        # done so, this field will be set and must be called at the end
        # of the coroutine.
        self.stack_context_deactivate = None
        if self.handle_yield(first_yielded):
            gen = result_future = first_yielded = None
            self.run() 

def test_getcoroutinelocals(self):
        @types.coroutine
        def gencoro():
            yield

        gencoro = gencoro()
        async def func(a=None):
            b = 'spam'
            await gencoro

        coro = func()
        self.assertEqual(inspect.getcoroutinelocals(coro),
                         {'a': None, 'gencoro': gencoro})
        coro.send(None)
        self.assertEqual(inspect.getcoroutinelocals(coro),
                         {'a': None, 'gencoro': gencoro, 'b': 'spam'}) 

def test_func_5(self):
        @types.coroutine
        def bar():
            yield 1

        async def foo():
            await bar()

        check = lambda: self.assertRaisesRegex(
            TypeError, "'coroutine' object is not iterable")

        with check():
            for el in foo(): pass

        # the following should pass without an error
        for el in bar():
            self.assertEqual(el, 1)
        self.assertEqual([el for el in bar()], [1])
        self.assertEqual(tuple(bar()), (1,))
        self.assertEqual(next(iter(bar())), 1) 

def run_until_complete(self):
        # Start all the coroutines.
        for coro in self._new:
            wait_for = coro.send(None)
            heapq.heappush(self._waiting, Task(wait_for, coro))
        # Keep running until there is no more work to do.
        while self._waiting:
            now = datetime.datetime.now()
            # Get the coroutine with the soonest resumption time.
            task = heapq.heappop(self._waiting)
            if now < task.waiting_until:
                # We're ahead of schedule; wait until it's time to resume.
                delta = task.waiting_until - now
                time.sleep(delta.total_seconds())
                now = datetime.datetime.now()
            try:
                # It's time to resume the coroutine.
                wait_until = task.coro.send(now)
                heapq.heappush(self._waiting, Task(wait_until, task.coro))
            except StopIteration:
                # The coroutine is done.
                pass 

def test_async_def(self):
        # Test that types.coroutine passes 'async def' coroutines
        # without modification

        async def foo(): pass
        foo_code = foo.__code__
        foo_flags = foo.__code__.co_flags
        decorated_foo = types.coroutine(foo)
        self.assertIs(foo, decorated_foo)
        self.assertEqual(foo.__code__.co_flags, foo_flags)
        self.assertIs(decorated_foo.__code__, foo_code)

        foo_coro = foo()
        def bar(): return foo_coro
        for _ in range(2):
            bar = types.coroutine(bar)
            coro = bar()
            self.assertIs(foo_coro, coro)
            self.assertEqual(coro.cr_code.co_flags, foo_flags)
            coro.close() 

def _coroutinestate(self):
        return inspect.getcoroutinestate(self.coroutine) 

def test_function_returning_awaitable(self):
        class Awaitable:
            def __await__(self):
                return ('spam',)

        @asyncio.coroutine
        def func():
            return Awaitable()

        coro = func()
        self.assertEqual(coro.send(None), 'spam')
        coro.close() 

def test_wrapper_object(self):
        def gen():
            yield
        @types.coroutine
        def coro():
            return gen()

        wrapper = coro()
        self.assertIn('GeneratorWrapper', repr(wrapper))
        self.assertEqual(repr(wrapper), str(wrapper))
        self.assertTrue(set(dir(wrapper)).issuperset({
            '__await__', '__iter__', '__next__', 'cr_code', 'cr_running',
            'cr_frame', 'gi_code', 'gi_frame', 'gi_running', 'send',
            'close', 'throw'})) 

def setUp(self):
        @types.coroutine
        def number_coroutine():
            for number in range(5):
                yield number
        async def coroutine():
            await number_coroutine()
        self.coroutine = coroutine() 

def test_gen(self):
        def gen_func():
            yield 1
            return (yield 2)
        gen = gen_func()
        @types.coroutine
        def foo(): return gen
        wrapper = foo()
        self.assertIsInstance(wrapper, types._GeneratorWrapper)
        self.assertIs(wrapper.__await__(), gen)

        for name in ('__name__', '__qualname__', 'gi_code',
                     'gi_running', 'gi_frame'):
            self.assertIs(getattr(foo(), name),
                          getattr(gen, name))
        self.assertIs(foo().cr_code, gen.gi_code)

        self.assertEqual(next(wrapper), 1)
        self.assertEqual(wrapper.send(None), 2)
        with self.assertRaisesRegex(StopIteration, 'spam'):
            wrapper.send('spam')

        gen = gen_func()
        wrapper = foo()
        wrapper.send(None)
        with self.assertRaisesRegex(Exception, 'ham'):
            wrapper.throw(Exception, Exception('ham'))

        # decorate foo second time
        foo = types.coroutine(foo)
        self.assertIs(foo().__await__(), gen) 

def test_duck_corogen(self):
        class CoroGenLike:
            def send(self): pass
            def throw(self): pass
            def close(self): pass
            def __await__(self): return self
            def __iter__(self): return self
            def __next__(self): pass

        coro = CoroGenLike()
        @types.coroutine
        def foo():
            return coro
        self.assertIs(foo(), coro)
        self.assertIs(foo().__await__(), coro) 

def test_genfunc(self):
        def gen(): yield
        self.assertIs(types.coroutine(gen), gen)
        self.assertIs(types.coroutine(types.coroutine(gen)), gen)

        self.assertTrue(gen.__code__.co_flags & inspect.CO_ITERABLE_COROUTINE)
        self.assertFalse(gen.__code__.co_flags & inspect.CO_COROUTINE)

        g = gen()
        self.assertTrue(g.gi_code.co_flags & inspect.CO_ITERABLE_COROUTINE)
        self.assertFalse(g.gi_code.co_flags & inspect.CO_COROUTINE)

        self.assertIs(types.coroutine(gen), gen) 

def test_duck_coro(self):
        class CoroLike:
            def send(self): pass
            def throw(self): pass
            def close(self): pass
            def __await__(self): return self

        coro = CoroLike()
        @types.coroutine
        def foo():
            return coro
        self.assertIs(foo(), coro)
        self.assertIs(foo().__await__(), coro) 

def tearDown(self):
        self.coroutine.close() 

def coroutine(func):
    """Decorator for asynchronous generators.

    Any generator that yields objects from this module must be wrapped
    in either this decorator or `engine`.

    Coroutines may "return" by raising the special exception
    `Return(value) <Return>`.  In Python 3.3+, it is also possible for
    the function to simply use the ``return value`` statement (prior to
    Python 3.3 generators were not allowed to also return values).
    In all versions of Python a coroutine that simply wishes to exit
    early may use the ``return`` statement without a value.

    Functions with this decorator return a `.Future`.  Additionally,
    they may be called with a ``callback`` keyword argument, which
    will be invoked with the future's result when it resolves.  If the
    coroutine fails, the callback will not be run and an exception
    will be raised into the surrounding `.StackContext`.  The
    ``callback`` argument is not visible inside the decorated
    function; it is handled by the decorator itself.

    .. warning::

       When exceptions occur inside a coroutine, the exception
       information will be stored in the `.Future` object. You must
       examine the result of the `.Future` object, or the exception
       may go unnoticed by your code. This means yielding the function
       if called from another coroutine, using something like
       `.IOLoop.run_sync` for top-level calls, or passing the `.Future`
       to `.IOLoop.add_future`.

    .. deprecated:: 5.1

       The ``callback`` argument is deprecated and will be removed in 6.0.
       Use the returned awaitable object instead.
    """
    return _make_coroutine_wrapper(func, replace_callback=True)