Python中协程coroutine适用场景分析

async def say_after(delay, what):
    await asyncio.sleep(delay)
    print(what)

import asyncio
async def main():
    print(f"started at {time.strftime('%X')}")
    print('hello world!')
    print(f"finished at {time.strftime('%X')}")
if __name__ == "__main__":
    # 入口函数通过asyncio.run()调用
    asyncio.run(main())

import asyncio
import time
async def say_after(delay, what):
    await asyncio.sleep(delay)
    print(what)
async def main():
    print(f"started at {time.strftime('%X')}")
    # 在前面加上await进行调用
    # 这种形式和正常的同步执行程序效果上没什么区别，仍是执行完上一步再执行下一步
    await say_after(1, 'hello')
    await say_after(2, 'world')
    print(f"finished at {time.strftime('%X')}")
if __name__ == "__main__":
    # 入口函数通过asyncio.run()调用
    asyncio.run(main())

import asyncio
import time
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class TestAsync:
    async def say_after(self,delay, what):
        await asyncio.sleep(delay)
        print(what)
    async def main(self):
        print(f"started at {time.strftime('%X')}")
        task_list = []
        # 等价于[1,2]
        for i in range(1, 3, 1):
            # 步骤一、使用asyncio.create_task()调用协程函数，封装成任务
            tmp_task = asyncio.create_task(self.say_after(i, 'hello'))
            task_list.append(tmp_task)
        # 第二步，await任务
        for tmp_task in task_list:
            await tmp_task
        print(f"finished at {time.strftime('%X')}")
if __name__ == "__main__":
    obj = TestAsync()
    asyncio.run(obj.main())