gen.py 文件源码

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.