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问题描述

I have the same issue as TheInterestedOne asked here.

I need to create two buttons for the user, and suggest that the user clicks one of the two buttons in the loop; so that the next iteration of the loop occurs only after the user's choice.

I read this source, but I can't make it work for buttons. I don't understand, how the widget attribute changes in the case of using buttons.

from functools import wraps
def yield_for_change(widget, attribute):
    def f(iterator):
        @wraps(iterator)
        def inner():
            i = iterator()
            def next_i(change):
                try:
                    i.send(change.new)
                except StopIteration as e:
                    widget.unobserve(next_i, attribute)
            widget.observe(next_i, attribute) //**button.on_click(on_button_clicked) 
                                                                may be?**
            # start the generator
            next(i)
        return inner
    return f


from ipywidgets import Button
button=Button()


def on_button_clicked():
    print("Button clicked.")


@yield_for_change(button, 'value')
def f():
    for i in range(10):
        print('did work %s'%i)
        x = yield
        button.on_click(on_button_clicked)

解决方案

This version uses awaitio and is modified for buttons.

from ipywidgets import Button
import asyncio

def wait_for_change(widget):
    future = asyncio.Future()
    def getvalue(change):
        future.set_result(change.description)
        widget.on_click(getvalue, remove=True) 
        # we need to free up the binding to getvalue to avoid an InvalidState error
        # buttons don't support unobserve
        # so use `remove=True` 
    widget.on_click(getvalue)
    return future

button = Button(description="wow")

list_to_tag = ["one", "two", "three", "four"]

async def f():
    for i in list_to_tag:
        print("going to tag {}".format(i))
        x = await wait_for_change(button)
        print("tagged {} with {}".format(i, x))
        print()

asyncio.create_task(f())
button