[PySide] using QProcess to run python function
Frank Rueter | OHUfx
frank at ohufx.com
Sat Jan 25 06:15:59 CET 2014
And of course I ran into trouble :-D
Here is my test code trying to ustilise QThread:
http://pastebin.com/Q26Q9M1M
The basic structure seems to work (the extra thread and the main thread
are running at the same time), but my UI does not update according to
the signal connections, e.g.:
When the thread starts the progress bar is supposed to be shown, the "Do
Work" button should be disabled, the "Cancel" button disabled.
etc.
I tried calling self.update() in the MainUI when the thread starts but
to no avail.
I'm sure I'm missing something obvious as usual.
I tried to adhere to what I learnt on this list about threading and
avoid sub-classing QThread.
Cheers,
frank
On 24/01/14 17:41, Frank Rueter | OHUfx wrote:
> Great, thanks. I shall adjust my code.
> I am interested in seeing how you would go about it, but let me have a
> go from scratch, I will be able to understand things much better
> afterwards :)
>
> Cheers,
> frank
>
>
> On 24/01/14 17:38, Sean Fisk wrote:
>> On Thu, Jan 23, 2014 at 10:44 PM, Frank Rueter | OHUfx
>> <frank at ohufx.com <mailto:frank at ohufx.com>> wrote:
>>
>> Much appreciated but as I mentioned, I think I jumped the gun
>> with my post and should be using QThread to hook the python code
>> to my QProgressBar and debug output window (QTextEdit).
>>
>> That would be a correct way to use |QProgressBar|. Also, for
>> subprocess output, I would consider using |QPlainTextEdit| instead of
>> |QTextEdit| as is is more performant with high amounts of text.
>>
>> If you are interested, I just wrote an asynchronous module for PySide
>> for the project on which I am currently working. It is based on
>> Python's futures <http://pythonhosted.org/futures/> module and works
>> great with Qt's signals/slots. Although the project is primarily
>> closed-source, I would be happy to share the async implementation
>> with you. I don't know if would fit your needs, but for us it's much
>> easier than manually spawning |QThread|s and even easier than
>> |QThreadPool|.
>>
>> Good luck!
>>
>> I will investigate that now
>>
>>
>>
>> On 24/01/14 16:08, Sean Fisk wrote:
>>> On Thu, Jan 23, 2014 at 9:42 PM, Frank Rueter | OHUfx
>>> <frank at ohufx.com <mailto:frank at ohufx.com>> wrote:
>>>
>>> Thanks Sean and Ryan,
>>>
>>> I'm still not quite clear on how this ties into QProcess.start()
>>>
>>>
>>> It doesn't tie in with |QProcess| at all. We're advising to
>>> avoid using that :)
>>>
>>> I do have a if __name__ ... block in the script in question.
>>> An example would certainly be awesome, but if it's less
>>> hassle, explaining how your and Ryan's advise helps use
>>> QProcess on a python module might already suffice. Maybe a
>>> simlpe example says it all though?!
>>>
>>>
>>> I will whip up a simple example for you, but it might take a few
>>> hours (lots of stuff to do right now).
>>>
>>> I'm not using python 3 btw
>>>
>>> Thanks guys for your help!!
>>>
>>> frank
>>>
>>>
>>> On 24/01/14 15:33, Sean Fisk wrote:
>>>>
>>>> Hi Frank,
>>>>
>>>> You should definitely avoid calling Python as a subprocess
>>>> if you can. As far as Ryan's example, I agree with the |if
>>>> __name__...| but I think that using the |imp| module is a
>>>> bit overkill. I would recommend using Setuptool's
>>>> |entry_points| keyword
>>>> <http://pythonhosted.org/setuptools/setuptools.html#automatic-script-creation>.
>>>> Or distutils' |scripts| keyword
>>>> <http://docs.python.org/2/distutils/setupscript.html#installing-scripts>,
>>>> if you must.
>>>>
>>>> An example of a well-known Python package which does this
>>>> is Pygments
>>>> <https://bitbucket.org/birkenfeld/pygments-main>, which has
>>>> a large "library" component but also comes with the
>>>> |pygmentize| command-line script. The Pygments codebase is
>>>> pretty large, so if you would like me to whip up a simpler
>>>> example I'd be glad to do so.
>>>>
>>>> Cheers,
>>>>
>>>> --
>>>> Sean Fisk
>>>>
>>>>
>>>> On Thu, Jan 23, 2014 at 9:17 PM, Frank Rueter | OHUfx
>>>> <frank at ohufx.com <mailto:frank at ohufx.com>> wrote:
>>>>
>>>> Sorry if I'm being thick, but I'm not quite
>>>> understanding how this helps to connect a python
>>>> function to qprocess?! All your code does is execute
>>>> the script, right?!
>>>> I can already call myscript.main() straight up, but
>>>> maybe I'm missing the point as I'm unfamiliar with the
>>>> imp module.
>>>>
>>>> Let me elaborate a little bit more:
>>>> myscript.main() calls a bunch of other python scripts
>>>> that (directly or through other scripts again) execute
>>>> external programs to do some conversion work. Those
>>>> external programs spit out their progress to stdout
>>>> which I can see fine when I run myscript.main()
>>>> manually in a python terminal.
>>>>
>>>> Now I need run myscript.main() via QProcess and grab
>>>> stdout to do be able to show a progress bar as well as
>>>> show stdout and stderr in a debug window inside my QT code.
>>>>
>>>>
>>>> Cheers,
>>>> frank
>>>>
>>>>
>>>>
>>>>
>>>> On 24/01/14 14:58, Ryan Gonzalez wrote:
>>>>> If you put an "if __name__ == '__main__'" and a main
>>>>> functions, you could always import the script from the
>>>>> GUI frontend. Example:
>>>>>
>>>>> myscript.py
>>>>>
>>>>> def main(argv):
>>>>> do_cool_stuff()
>>>>> return 0
>>>>>
>>>>> if __name__ == '__main__':
>>>>> sys.exit(main(sys.argv))
>>>>>
>>>>> mygui.py(Python 2):
>>>>>
>>>>> import imp
>>>>>
>>>>> ...
>>>>>
>>>>> main = imp.load_module('myscript',
>>>>> *imp.find_module('myscript'))
>>>>>
>>>>> main.main(my_argv)
>>>>>
>>>>> mygui.py(Python 3):
>>>>>
>>>>> import importlib.machinery
>>>>>
>>>>> main =
>>>>> importlib.machinery.SourceFileLoader('myscript',
>>>>> 'myscript.py').load_module('myscript')
>>>>>
>>>>> main.main(my_argv)
>>>>>
>>>>>
>>>>> On Thu, Jan 23, 2014 at 7:48 PM, Frank Rueter | OHUfx
>>>>> <frank at ohufx.com <mailto:frank at ohufx.com>> wrote:
>>>>>
>>>>> Hi all,
>>>>>
>>>>> I got a little code design question:
>>>>>
>>>>> I have a python script that does a lot of file
>>>>> processing/converting/uploading etc and I'd like
>>>>> to write a decent
>>>>> interface for it now.
>>>>> The main goal is to be able to show the user
>>>>> detailed info about the
>>>>> current step and progress as well as clean up
>>>>> properly in case the whole
>>>>> thing is cancelled.
>>>>>
>>>>> My existing python code needs to stay independent
>>>>> of QT so any
>>>>> application that supports python can use it.
>>>>> I am wondering now how to best connect the python
>>>>> script and the PySide
>>>>> code. Should I just run the script as an argument
>>>>> to the python
>>>>> interpreter like I would with any other program? E.g.:
>>>>>
>>>>> process = QtCore.QProcess(self)
>>>>> process.start(<path_to_python>,
>>>>> <path_to_python_script>)
>>>>>
>>>>> As simple as this seems, it feels odd to use
>>>>> python to call itself as an
>>>>> external program.
>>>>>
>>>>>
>>>>> I'm happy to go that way but am curious how others
>>>>> are doing this?!
>>>>>
>>>>> Cheers,
>>>>> frank
>>>>>
>>>>> _______________________________________________
>>>>> PySide mailing list
>>>>> PySide at qt-project.org <mailto:PySide at qt-project.org>
>>>>> http://lists.qt-project.org/mailman/listinfo/pyside
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Ryan
>>>>> If anybody ever asks me why I prefer C++ to C, my
>>>>> answer will be simple: "It's
>>>>> becauseslejfp23(@#Q*(E*EIdc-SEGFAULT. Wait, I don't
>>>>> think that was nul-terminated."
>>>>>
>>>>
>>>>
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>>>>
>>>>
>>>
>>>
>>
>>
>
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