python - Any flaw in the logic of using qtimer and qthread? -

i have gui developed using pyqt4 has run button. on run button click, invoke timer , thread. timer keeps monitoring thread. on thread invoke command prompt execute test cases. want thread alive till command prompt opened , want dead once close command prompt.

the code had written achieve below. logic flaws? or better way achieve this?

self.connect(self.run_button, signal('clicked()'), self.runscript)   def runscript(self):     self.timer = qtimer()     self.timer.connect(self.timer, signal("timeout()"),self.senddata)     self.timer.start(1000)   def senddata(self):       if self.run_timer:         run_monitor_object = runmonitor()         print 'starting thread...........'         run_monitor_object.start()         self.run_timer = false      if run_monitor_object.isalive():         print 'thread alive...'     else:         print 'thread dead....'  class runmonitor(threading.thread):     def __init__(self, parent=none):         threading.thread.__init__(self)     def run(self):         print 'invoking command prompt..........'         subprocess.call(["start", "/dc:\\scripts", "scripts_to_execute.bat"], shell=true) 

when run this, following error...

unboundlocalerror: local variable 'run_monitor_object' referenced before assignment @ if run_monitor_object.isalive():

just wondering how else,

this code:

if self.run_timer:     run_monitor_object = runmonitor()     print 'starting thread...........'     run_monitor_object.start()     self.run_timer = false  if run_monitor_object.isalive():     print 'thread alive...' else:     print 'thread dead....' 

is wrong. if first branch isn't taken (perhaps in second invocation when self.run_timer true), run_monitor_object isn't assigned, , attempt use in second if.

to make work, make run_monitor_thread instance variable of class.

also, why start thread in timer? needlessly complicating logic. start when create timer. timer used monitor it.