The solution to gen.Return(\'hello\') appearing in tornado-Python Tutorial-php.cn

The solution to gen.Return(\'hello\') appearing in tornado

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Release： 2024-02-29 22:58:02

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$The solution to gen.Return(\hello\) appearing in tornado$

The reason for the error

In python, Tornado is a networkframework# based on the event loop ##. It uses coroutines to handle concurrency, gen.Return("hello") is a method for returning values in coroutines. When using Tornado's asynchronous capabilities, use gen.Return() to return a value in a coroutine.

How to solve

In Tornado, use yield and gen.Return() to return values. If you want to return a value in a coroutine, you can use yield and gen.Return() to achieve your goal.

For example:

@gen.coroutine
def my_coroutine():
result = yield some_async_call()
raise gen.Return(result)

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Use async

io.run() or tornado.gen.convert_yielded() outside the function to get the return value.

result = await my_coroutine()

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If you want to return a value in a coroutine, you should use yield and gen.Return() to achieve your goal.

Usage example

The following is a simple example of using coroutines in Tornado and returning values:

import tornado.ioloop
import tornado.gen

@tornado.gen.coroutine
def my_coroutine():
result = yield some_async_call()
raise tornado.gen.Return(result)

def handle_result(result):
print(result)

if __name__ == "__main__":
result = tornado.ioloop.IOLoop.current().run_sync(my_coroutine)
handle_result(result)

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Some_async_call() here is an asynchronous function.

If you want to get the return value outside the function, you can do this:

result = await my_coroutine()

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Of course, async/await syntax can also be used, which requires adding the async modifier before the function and using await when calling the function.

async def my_coroutine():
result = await some_async_call()
return result

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In the above example, result is the return value, which can be processed in handle_result().

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