[Interest] how to restart QProcess after it fails?

Frank Rueter | OHUfx frank at ohufx.com
Sat Jun 1 09:26:49 CEST 2019


Hi all,

I am using QProcess to launch an external application. The main part 
work without trouble, but I need to check for license errors and if one 
occurred, I need would like to restart the existing process with all 
it's environment settings and signal connections a certain number of times.

I connect QProcess.readyReadStandardError to a slot that toggles an 
attribute called self.in_error to True.
I also connect QProcess.stateChanged to another slot which looks like this:

     def __retry_process(self, process_state):
         max_retries = 5
         if (process_state == QtCore.QProcess.NotRunning) and self.in_error:
             # process has finished in an error state, so try to run it 
again
             self.current_try += 1
             print 'retrying {}/{}'.format(self.current_try, max_retries)
             self.process.start(self.process.program(), 
self.process.arguments())

This prints the line "retrying 1/5" but after that nothing happens. I 
can't see any log output from self.process so if seems to simply not be 
running the second time around.
I thought this would recursively call self.process 5 times after failing 
the first time, since self.process.stateChanged is still connected to 
self__retry_process(), and the current_try attribute is on class level 
where it gets incremented on every unsuccessful try.

I am obviously wrong about that. Could someboy help me out please?

Cheers,
frank


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