python 3.x - Connecting keyRelease events to PyQt4 widgets -

this duplicate question, have ask because other answers aren't helping in case since new pyqt (switched tkinter few days ago).

i wondering possible connect event widget >

 self.lineedit = qtgui.qlineedit(self.frame)   self.lineedit.keyreleaseevent(lambda: somefunction(qtcore.qt.key_a ))   self.lineedit.setobjectname(_fromutf8("lineedit"))   self.horizontallayout.addwidget(self.lineedit) 

and then...

def somefunction(event):     print(event)     ... 

my question how bind specific event widget, , connect event function... btn.clicked.connect(function_goes_here)

in tkinter it's :

self.entry.bind("<keyrelease-a>", lambda event: somefunction(event)) 

simple working example great, if possible

there number of different ways achieve this. generic way listen all events given widget, install event-filter on it:

class mainmwindow(qtgui.qmainwindow):     def __init__(self):         ...         self.lineedit = qtgui.qlineedit(self.frame)         self.lineedit.installeventfilter(self)      def eventfilter(self, source, event):         if source self.lineedit:             if event.type() == qtcore.qevent.keyrelease:                 print('key release:', event.key())                 # following line eat key event                 # return true         return super(mainmwindow, self).eventfilter(source, event) 

alternatively, can sub-class widget, re-implement relevant event handler, , emit custom signal:

class lineedit(qtgui.qlineedit):     keyreleased = qtcore.pyqtsignal(int)      def keyreleaseevent(self, event):         self.keyreleased.emit(event.key())         super(lineedit, self).keyreleaseevent(event)  class mainmwindow(qtgui.qmainwindow):     def __init__(self):         ...         self.lineedit = lineedit(self.frame)         self.lineedit.keyreleased.connect(self.handlekeyrelease)      def handlekeyrelease(self, key):         print('key release:' key) 

a more hackish variation on overwrite method directly:

class mainmwindow(qtgui.qmainwindow):     def __init__(self):         ...         self.lineedit = qtgui.qlineedit(self.frame)         self.lineedit.keyreleaseevent = self.handlekeyrelease      def handlekeyrelease(self, event):         print('key release:', event.key())         qtgui.qlineedit.keyreleaseevent(self.lineedit, event) 

note if don't want invoke default event handling, can omit call base-class method.