python协程获取返回值(四种方式)-优快云博客

本文链接：https://blog.youkuaiyun.com/Liquor6/article/details/124631744

本文对比了asyncio库中async/await配合future、create_task和回调函数的不同获取返回值方式，包括确保future对象的result、使用loop的create_task以及带有回调的异步任务。通过实例展示了每种方法的执行流程和结果输出。

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一、通过ensure_future获取，本质是future对象中的result方法

import asyncio
from functools import partial

async def talk(name):
	print("talk running!!!")
	await asyncio.sleep(1)
	return f"{name} talk"

async def sleep(work):
	print("sleep running!!!")
	await asyncio.sleep(0.1)
	return f"{work} sleep"

if __name__ == "__main__":
	# 通过ensure_future获取，本质是future对象中的result方法
	loop = asyncio.get_event_loop()
	get_future1 = asyncio.ensure_future(talk("Dog"))
	get_future2 = asyncio.ensure_future(sleep("Cat"))
	loop.run_until_complete(get_future1)
	loop.run_until_complete(get_future2)
	print(get_future1.result())
	print(get_future2.result())

打印结果：

talk running!!!
sleep running!!!
Dog talk
Cat sleep

二、使用loop自带的create_task，获取返回值

import asyncio
from functools import partial

async def talk(name):
	print("talk running!!!")
	await asyncio.sleep(1)
	return f"{name} talk"

async def sleep(work):
	print("sleep running!!!")
	await asyncio.sleep(0.1)
	return f"{work} sleep"

if __name__ == "__main__":
	# 使用loop自带的create_task，获取返回值
	loop = asyncio.get_event_loop()
	task1 = loop.create_task(talk("Dog"))
	task2 = loop.create_task(sleep("Cat"))
	loop.run_until_complete(task1)
	loop.run_until_complete(task2)
	print(task1.result())
	print(task2.result())

打印结果：

talk running!!!
sleep running!!!
Dog talk
Cat sleep

三、使用callback，一旦await地方的内容运行完，就会运行callback

import asyncio
from functools import partial

async def tack(name):
	print("talk running!!!")
	await asyncio.sleep(1)
	return f"{name} talk"

async def sleep(work):
	print("sleep running!!!")
	await asyncio.sleep(0.1)
	return f"{work} sleep"

def callback(value):
	print(f"主动抛出接收返回值：{value}")

if __name__ == "__main__":
	# 使用callback，一旦await地方的内容运行完，就会运行callback
	loop = asyncio.get_event_loop()
	task1 = loop.create_task(tack("Dog"))
	task2 = loop.create_task(sleep("Cat"))
	task1.add_done_callback(callback)
	task2.add_done_callback(callback)
	loop.run_until_complete(task1)
	loop.run_until_complete(task2)
	print(task1.result())
	print(task2.result())

打印结果：

talk running!!!
sleep running!!!
主动抛出接收返回值：<Task finished name='Task-2' coro=<sleep() done, defined at D:/python_files/py2022_02/Case01/ceshi.py:24> result='Cat sleep'>
主动抛出接收返回值：<Task finished name='Task-1' coro=<tack() done, defined at D:/python_files/py2022_02/Case01/ceshi.py:19> result='Dog talk'>
Dog talk
Cat sleep

四、使用partial这个模块向callback函数中传入值

import asyncio
from functools import partial

async def talk(name):
	print("talk running !!!")
	await asyncio.sleep(1)
	return f"{name} talk"

async def sleep(work):
	print("sleep running!!!")
	await asyncio.sleep(0.1)
	return f"{work} sleep"
	
def callback(value):
    print(f"主动抛出接收返回值：{value}")

if __name__ == "__main__":
	# 使用partial这个模块向callback函数中传入值
	loop = asyncio.get_event_loop()
	task1 = loop.create_task(talk("Dog"))
	task2 = loop.create_task(sleep("Cat"))
	task1.add_done_callback(partial(callback))
	task2.add_done_callback(partial(callback))
	loop.run_until_complete(task1)
	loop.run_until_complete(task2)
	print(task1.result())
	print(task2.result())

打印结果：

talk running !!!
sleep running!!!
主动抛出接收返回值：<Task finished name='Task-2' coro=<sleep() done, defined at D:/python_files/py2022_02/Case01/ceshi.py:25> result='Cat sleep'>
主动抛出接收返回值：<Task finished name='Task-1' coro=<talk() done, defined at D:/python_files/py2022_02/Case01/ceshi.py:19> result='Dog talk'>
Dog talk
Cat sleep