This is my third project using PySide and I came across an unusual error when trying to use custom Signals and Slots. Below is a variation of what I am working on that is giving me the AttributeError. I have used a similar syntax for other projects with no issues, so any help is appreciated. I do understand per the error that I am trying to connect a function to a slot, however if I use the @Signal decorator I receive a separate error basically saying that I cannot use it.
from PySide2.QtWidgets import *
from PySide2.QtGui import *
from PySide2.QtCore import *
import sys
class TestSignal(QObject):
signal = Signal(float)
def __init__(self):
QObject.__init__(self)
def changed(self, test_value: float):
self.signal.emit(test_value)
class Main(QMainWindow):
def __init__(self):
QMainWindow.__init__(self)
self.signal = TestSignal()
self.signal.changed.connect(self.test_slot) # this is where the error occurs
self.central_widget = QWidget()
self.go_button = QPushButton("Emit")
self.go_button.clicked.connect(self.emit_signal)
self.change_label = QLabel("Push Button")
self.test_layout = QVBoxLayout()
self.test_layout.addWidget(self.change_label)
self.test_layout.addWidget(self.go_button)
self.setCentralWidget(self.central_widget)
self.central_widget.setLayout(self.test_layout)
self.show()
@Slot(float)
def test_slot(self, test_value):
self.change_label.setText("Emitted Signal successcully")
def emit_signal(self):
self.signal.changed()
if __name__ == '__main__':
app = QApplication(sys.argv)
window = Main()
app.exec_()
sys.exit(0)
Advertisement
Answer
The signal is called “signal”, “changed” is just a method where the signal is emitted. Recommendation: Use more descriptive names to avoid this type of confusion
class TestSignal(QObject):
signal = Signal(float)
def changed(self, test_value: float):
self.signal.emit(test_value)
class Main(QMainWindow):
def __init__(self):
QMainWindow.__init__(self)
self.signal = TestSignal()
self.signal.signal.connect(self.test_slot)
self.central_widget = QWidget()
self.go_button = QPushButton("Emit")
self.go_button.clicked.connect(self.emit_signal)
self.change_label = QLabel("Push Button")
self.test_layout = QVBoxLayout()
self.test_layout.addWidget(self.change_label)
self.test_layout.addWidget(self.go_button)
self.setCentralWidget(self.central_widget)
self.central_widget.setLayout(self.test_layout)
self.show()
@Slot(float)
def test_slot(self, test_value):
self.change_label.setText("Emitted Signal successcully {}".format(test_value))
def emit_signal(self):
self.signal.changed(5.0)