[PyQt] Integrating asyncio with Qt event loop?

[Arve Knudsen]

Hi Erik

I think you could use an asyncio.Future for this purpose. You can yield
from the Future, and set its result upon arrival of the signal. I've
concocted an example program that should show what I mean; it creates a
2-second timer which is waited on asynchronously, once its timeout fires
the program exits:

    import quamash
    import asyncio
    from PyQt5.QtWidgets import *
    from PyQt5.QtCore import *


    @asyncio.coroutine
    def _go():
        def on_timeout():
            print('Timeout')
            fut.set_result(True)

        fut = asyncio.Future()
        timer = QTimer()
        timer.setSingleShot(True)
        timer.setInterval(2000)
        timer.start()
        timer.timeout.connect(on_timeout)
        print('Yielding until signal...')
        yield from fut
        print('Continuing execution after yield from')

    with quamash.QEventLoop(app=QApplication([])) as loop:
        w = QMainWindow()
        w.show()
        loop.run_until_complete(_go())
    print('Coroutine has ended')

HTH,
Arve


On Thu, Aug 7, 2014 at 12:31 AM, Erik Hvatum <ice.rikh at gmail.com> wrote:

> Thank you :)
>
> A quick question to help as I dig into this: how might one go about "yield
> from wait_for_a_qt_signal"?  That is, I want my coroutine to resume
> execution when some certain signal is emitted.  Perhaps this desire
> indicates that I'm going about things the wrong way...
>
> -Erik
>
> PS: forgot to reply to the list the first time around
>
>
> On Sat, Jul 5, 2014 at 12:34 PM, Arve Knudsen <arve.knudsen at gmail.com>
> wrote:
>
>> Quamash, in the unix branch (https://github.com/aknuds1/quamash/tree/unix),
>> now works perfectly for thread and subprocess execution on OS X, Linux and
>> Windows, I'm pleased to say. Would love some feedback.
>>
>> Arve
>>
>>
>> On Tue, Jul 1, 2014 at 3:12 PM, Arve Knudsen <arve.knudsen at gmail.com>
>> wrote:
>>
>>> Now, even subprocess execution works. At least on Windows/PyQt, haven't
>>> tested on other platforms.
>>>
>>> Arve
>>>
>>>
>>> On Mon, Jun 30, 2014 at 4:03 PM, Arve Knudsen <arve.knudsen at gmail.com>
>>> wrote:
>>>
>>>> Erik, Tamás, feel free to try my Quamash fork
>>>> <https://github.com/aknuds1/quamash>, it's currently quite functional,
>>>> except that subprocess execution is somehow broken.
>>>>
>>>> Arve
>>>>
>>>> On Fri, Jun 27, 2014 at 1:34 PM, Arve Knudsen <arve.knudsen at gmail.com>
>>>> wrote:
>>>>
>>>>> My fork is now semi-functional with Python 3.4 and PyQt 5. I can at
>>>>> least perform simple asynchronous tasks within a Qt application, but lots
>>>>> remain to implement.
>>>>>
>>>>> Arve
>>>>>
>>>>>
>>>>> On Fri, Jun 27, 2014 at 9:24 AM, Arve Knudsen <arve.knudsen at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> I've created a fork on GitHub: https://github.com/aknuds1/quamash.
>>>>>> Do you know where to locate information on writing an asyncio event loop
>>>>>> though? Not sure where to begin.
>>>>>>
>>>>>> Thanks,
>>>>>> Arve
>>>>>>
>>>>>>
>>>>>> On Thu, Jun 26, 2014 at 9:30 PM, Arve Knudsen <arve.knudsen at gmail.com
>>>>>> > wrote:
>>>>>>
>>>>>>> Thanks. I'm thinking I might try to modify his code, if it isn't too
>>>>>>> much work.
>>>>>>>
>>>>>>> Arve
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Jun 26, 2014 at 7:32 PM, Tamás Bajusz <gbtami at gmail.com>
>>>>>>> wrote:
>>>>>>>
>>>>>>>> Unfortunately, I know that github project only. (
>>>>>>>> https://github.com/harvimt/quamash)
>>>>>>>> Try to contact him at mark.harviston at gmail.com
>>>>>>>>
>>>>>>>>
>>>>>>>> On Thu, Jun 26, 2014 at 7:27 PM, Arve Knudsen <
>>>>>>>> arve.knudsen at gmail.com> wrote:
>>>>>>>>
>>>>>>>>> Tamás, has Mark Harviston's implementation been updated to work
>>>>>>>>> with the latest Python (3.4)? I think I read somewhere that it's based on
>>>>>>>>> an outdated API.
>>>>>>>>>
>>>>>>>>> Arve
>>>>>>>>>
>>>>>>>>> On Thu, Jun 26, 2014 at 6:29 PM, Tamás Bajusz <gbtami at gmail.com>
>>>>>>>>> wrote:
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> http://haypo-notes.readthedocs.org/asyncio.html#replacing-the-event-loop
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Thu, Jun 26, 2014 at 5:20 PM, Arve Knudsen <
>>>>>>>>>> arve.knudsen at gmail.com> wrote:
>>>>>>>>>>
>>>>>>>>>>>  Hi guys
>>>>>>>>>>>
>>>>>>>>>>> I am looking to integrate Python 3.4 asyncio
>>>>>>>>>>> <https://docs.python.org/3/library/asyncio.html> with Qt's
>>>>>>>>>>> event loop (via PyQt 5), specifically in order to asynchronously monitor
>>>>>>>>>>> output (stdout/stderr) from a child process. Maybe this is somewhat
>>>>>>>>>>> off-topic for this list, but can someone tell me if such integration exists
>>>>>>>>>>> (and works)?
>>>>>>>>>>>
>>>>>>>>>>> Thanks,
>>>>>>>>>>> Arve
>>>>>>>>>>>
>>>>>>>>>>> _______________________________________________
>>>>>>>>>>> PyQt mailing list    PyQt at riverbankcomputing.com
>>>>>>>>>>> http://www.riverbankcomputing.com/mailman/listinfo/pyqt
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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