[Solved] Questions about the signal handlers' style (old working but not the new way)? [Python PyQt4]



  • Hi,

    I am new to PyQt, but I like it since it is very handy! Glad to be here.

    I am running into a weird issue that the old way of signal handling worked, but the new way failed. Please let me know if I did anything wrong. It is using PyQt4.

    So my application has a main window, and I need to make it pop a QDialog for some warning messages and few buttons that user can interact with (sorta like email I guess). So I create a custom QDialog class, add a QDialogButtonBox with three QPushButton. The idea is when a user click a button, the QDialog will close, and return different int value of exec_() to the main window, so my application can process accordingly.

    What I did (and worked) was:
    @
    self.aButton = QtGui.QPushButton("Afunc")
    self.buttonBox = QtGui.QDialogButtonbox()
    self.aButton.addButton (self.aButton, QtGui.QDialogButtonBox.RejectRole)
    mainLayout.addWidget (self.buttonBox)
    self.connect(self.aButton, QtCore.SIGNAL("clicked()"), self.Afunc)

    def aFunc(self):
    self.setResult(3)
    @

    However, I was told there is a new style to connect buttons, which is below
    @
    self.aButton.clicked.connect(self.aFunc)
    @

    So I changed it, but then I can never get the desired return value 3 when press the A button. Also I noticed if changed the button's role from RejectRole to AcceptRole or ActionRole, it will be worse -- the QDialog will not close, and thus my application did not receive any return value from exec__(). Nothing happened.

    My questions are:

    1. Why the new style did not work? Am I missing something?
    2. Why it has to be RejectRole for the button? I do want some button doing nothing but close the QDialog, pretty much like the OK button, and its default return value is desired. I thought it should be AcceptRole, no?

    Thank you very much!

    [edit: changed for coding tags @ SGaist]


  • Lifetime Qt Champion

    Hi and welcome to devnet,

    The new connection style is only available with Qt 5 so you would also have to use PyQt 5.

    Closing the dialog doing nothing correspond to a "rejection". You should connect the QDialogButtonBox (e.g. accepted, rejected) signals to the corresponding QDialog slot. You can use the clicked signal which has a button parameter to set the result accordingly.

    Hope it helps



  • Hi Sgaist,

    Thank you very much for the help. I did not know the new style is only for Qt 5.

    I am not really getting what you suggested for the signal, so could you please list some codes. Thanks!



  • Update:
    I ended up used QHBoxLayout instead of the QDialogButtonBox, and everything worked. Thanks for the help!

    So yeah, the new style works for me in PyQt4, just a note.

    Will close the thread if I can.


  • Lifetime Qt Champion

    What do you mean by QHBoxLayout instead of the QDialogButtonBox ?


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