Jupyter Notebook Async functions

Question

In the code below, I'd like the following behavior:

When the user clicks the button I've defined in App Mode, I want the print_async routine inside of it to be invoked, which waits for 2 seconds and then prints ""this is async print from buttonCLicked", then I want the print after which is "button clicked!" to appear. Instead what I get is an interpreter error:

Any help appreciated.

File "cell_name", line 6 SyntaxError: 'await' outside async function

from IPython.display import display
from ipywidgets import widgets
import asyncio
#DO NOT CHANGE THIS CELL
#Define an async function
async def print_async(message):
    await asyncio.sleep(2)
    print(message)
# Show that we can print from the top-level jupyter terminal
await print_async("This is a top-level async print")
#Define a callback function for the button
def onButtonClicked(_):
    await print_async("this is async print from buttonCLicked")
    print("button clicked!")

button = widgets.Button(
    description='Click me',
    disabled=False,
    button_style='', # 'success', 'info', 'warning', 'danger' or ''
    tooltip='Click me',
    icon=''
)

button.on_click(onButtonClicked)
display(button)

button = widgets.Button(
    description='Click me',
    disabled=False,
    button_style='', # 'success', 'info', 'warning', 'danger' or ''
    tooltip='Click me',
    icon=''
)

button.on_click(onButtonClicked)
display(button)
Goal: Get the button click to call the print_async method

jakevdp · Accepted Answer · 2020-01-07 16:45:16Z

1

You can do this with the asyncio.run function (Requires Python 3.7 or newer):

In your code it would look like this:

def onButtonClicked(_):
    asyncio.run(print_async("this is async print from buttonCLicked"))
    print("button clicked!")

edited Jan 7, 2020 at 16:45

answered Jan 7, 2020 at 16:36

jakevdp

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1 Comment

Nazim Bharmal Over a year ago

I think this misses the syntax error as line 6, await print_async("This is a top-level async print") which is incorrect since it isn't within a co-routine defn. Remove it and I believe the concurrent programming logic would be valid.

saravana_kumaran · Accepted Answer · 2023-05-16 06:35:53Z

0

First of all, You cannot use await keyword outside async function. If that is the entry point to your asynchronous program, use asyncio.run() function with function call as a parameter to run() method to call that co-routine.

edited May 16, 2023 at 6:35

answered May 16, 2023 at 6:35

saravana_kumaran

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