Handling unixSignal in PyQt in a console app

If you try to use the python standard unix signal handlers with QCoreApplication the handler never gets called. Comment out the creation(and exec_) call, the signal handler gets called as expected.

So, I'm forced to use the unixSignal qt SIGNAL of QCoreApplication but I can't get it to actually trap the SIGHUP.

Code:

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import sys
import time
from PyQt4 import QtCore
 
HUP_EVENT = QtCore.QEvent.User + 1
 
 
class Application(QtCore.QCoreApplication):
    def __init__(self):
        QtCore.QCoreApplication.__init__(self, sys.argv)
 
        self.connect(self, QtCore.SIGNAL('unixSignal(int)'), self.onUnixSignal)
        self.connect(self, QtCore.SIGNAL('sigHUP()'), self.onSIGHUP)
 
 
    def onUnixSignal(self, signum):
        print 'unix signal'
        if signum == signal.SIGHUP:
            self.postEvent(self, QtCore.QEvent(HUP_EVENT))
 
    def event(self, event):
        print 'In event, %s' % event.type()
        if event.type() == 1:
            self.emit(QtCore.SIGNAL("sigHUP()"))
            return True
 
        return False
 
    def onSIGHUP(self):
        print 'in onsighup'
        self.quit()
 
 
if __name__ == '__main__':
    app = Application()
    sys.exit(app.exec_())
    print 'Done'

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Prints

Quote:

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In event, 67
Hangup

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Which shows the unix signal was not trapped.

This shows PyQt trashes the python signal module handlers

Code:

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import signal
import sys
import time
from PyQt4 import QtCore
 
HUP_EVENT = QtCore.QEvent.User + 1
 
 
def sighup_handler(signum, frame):
    print 'python signal handler'
    self.postEvent(self, QtCore.QEvent(HUP_EVENT))
 
 
 
class Application(QtCore.QCoreApplication):
    def __init__(self):
        QtCore.QCoreApplication.__init__(self, sys.argv)
 
        self.connect(self, QtCore.SIGNAL('sigHUP()'), self.onSIGHUP)
 
 
    def event(self, event):
        print 'In event, %s' % event.type()
        if event.type() == HUP_EVENT:
            self.emit(QtCore.SIGNAL("sigHUP()"))
            return True
 
        return False
 
    def onSIGHUP(self):
        print 'in onsighup'
        self.quit()
 
 
if __name__ == '__main__':
    app = Application()
 
    signal.signal(signal.SIGHUP, sighup_handler)
 
    sys.exit(app.exec_())
 
    print 'Done'

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Prints

Quote:

---

In event, 67

---

and then nothing.

Comment out the instantiation of the app and...

Code:

---

import signal
import sys
import time
from PyQt4 import QtCore
 
HUP_EVENT = QtCore.QEvent.User + 1
 
 
def sighup_handler(signum, frame):
    print 'python signal handler'
    self.postEvent(self, QtCore.QEvent(HUP_EVENT))
 
 
 
class Application(QtCore.QCoreApplication):
    def __init__(self):
        QtCore.QCoreApplication.__init__(self, sys.argv)
 
        self.connect(self, QtCore.SIGNAL('sigHUP()'), self.onSIGHUP)
 
 
    def event(self, event):
        print 'In event, %s' % event.type()
        if event.type() == HUP_EVENT:
            self.emit(QtCore.SIGNAL("sigHUP()"))
            return True
 
        return False
 
    def onSIGHUP(self):
        print 'in onsighup'
        self.quit()
 
 
if __name__ == '__main__':
#    app = Application()
 
    signal.signal(signal.SIGHUP, sighup_handler)
 
#    sys.exit(app.exec_())
    time.sleep(30)
 
    print 'Done'

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Quote:

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python signal handler
Traceback (most recent call last):
File "sharedb/app.py", line 41, in <module>
time.sleep(30)
File "sharedb/app.py", line 11, in sighup_handler
self.postEvent(self, QtCore.QEvent(HUP_EVENT))
NameError: global name 'self' is not defined

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