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Working with signal sender in Qt bindings
I tried to create dialog box with several controls of same type and use same signal handler for all of them. But self.sender() returned None.
class Test_Dialog(pya.QDialog):
def __init__(self, parent, current_view, names):
super(Test_Dialog, self).__init__(parent)
self.current_view = current_view
self.setWindowTitle('Test')
self.resize(200, 400)
layout = pya.QVBoxLayout(self)
self.setLayout(layout)
for name in names:
check_box = pya.QCheckBox(name, self)
check_box.tristate = False
check_box.checkState = pya.Qt_CheckState('Checked')
check_box.stateChanged = self.check_box_stateChanged
layout.addWidget(check_box)
def check_box_stateChanged(self, state):
print(self.sender())
def test():
app = pya.Application.instance()
current_view = app.main_window().current_view()
window = Test_Dialog(app.main_window(), current_view, ['1', '2', '3'])
window.show()
I used 0.26.4 Ubuntu build from KLayout site.
Couple of more questions:
- In C++ Qt
sender()is cast to proper type withqobject_cast. Is there equivalent in Qt bindings? If not, howsender()should be used (for example, custom properties)? - Is my understanding of Qt constant (
pya.Qt_CheckState('Checked')in code above) correct? If so, I think it'll be reasonable to make them enum classes.
Comments
Hi,
currently, "sender()" isn't available in KLayout Qt binding flavour.
The reason is that unlike in C++ Qt, the receiver can be any method of any class. In fact the binding is not built upon an emulation of the Qt signal/slot mechanism. You can actually add any callable to a Qt signal.
This means you can use a lambda to add the sender parameter in case you want the same method to handle two events from different signals:
When the actions you want to take on a signal are not complex, you can even only use a lambda and you don't need a method for handling the signal.
Regards,
Matthias
Hi, Matthias!
Thank you for explanations! It may be reasonable to add this to documentation.