pythonpython-asyncio

Python | AsyncIO | TypeError: a coroutine was expected


I'm trying python coroutine programming using asyncio. This is my code.

import asyncio

async def coro_function():
    return 2 + 2

async def get():
    return await coro_function()

print(asyncio.iscoroutinefunction(get))

loop = asyncio.get_event_loop()
a1 = loop.create_task(get)
loop.run_until_complete(a1)

But when I execute it, it gives me error

True
Traceback (most recent call last):
  File "a.py", line 13, in <module>
    a1 = loop.create_task(get)
  File "/home/alie/anaconda3/lib/python3.7/asyncio/base_events.py", line 405, in create_task
    task = tasks.Task(coro, loop=self)
TypeError: a coroutine was expected, got <function get at 0x7fe1280b6c80>

How to solve it?


Solution

  • You're passing in the function get.

    In order to pass in a coroutine, pass in get().

    a1 = loop.create_task(get())
    loop.run_until_complete(a1)
    

    Take a look at the types:

    >>> type(get)
    <class 'function'>
    >>> print(type(get()))
    <class 'coroutine'>
    

    get is a coroutine function, i.e. a function that returns a coroutine object, get(). For more information and a better understanding of the fundamentals, take a look at the docs.