为什么 PyQt 中的这段代码允许我不选中所有单选按钮？

Question

我使用 PyQt 编写了一个迷你代码，当我注意到它允许我不选中左侧的所有按钮时，我感到很惊讶。 我不想要这种行为：应该始终选择其中之一。 不过，窗口的右侧有效。 我真的不知道为什么。 这是代码：

from PyQt5 import QtWidgets, QtGui, QtCore

class Win(QtWidgets.QDialog):
    def __init__(self, parent=None):
        super(Win, self).__init__(parent)
        top_layout = QtWidgets.QHBoxLayout()

        top_layout_1 = QtWidgets.QHBoxLayout()
        self.thresh_btns = [QtWidgets.QRadioButton('L1'),
                            QtWidgets.QRadioButton('L2'),
                            QtWidgets.QRadioButton('L3')]
        self.thresh_btns[0].setChecked(True)
        for btn in self.thresh_btns:
            top_layout_1.addWidget(btn)

        timestamp_groupbox = QtWidgets.QGroupBox('Timestamp')
        top_layout_2 = QtWidgets.QVBoxLayout()
        self.timestamp_current = QtWidgets.QRadioButton('Current')
        self.timestamp_current.setChecked(True)
        self.timestamp_target = QtWidgets.QRadioButton('Last')
        top_layout_2.addWidget(self.timestamp_current)
        top_layout_2.addWidget(self.timestamp_target)
        timestamp_groupbox.setLayout(top_layout_2)

        top_layout.addLayout(top_layout_1)
        top_layout.addWidget(timestamp_groupbox)
        self.setLayout(top_layout)

if __name__ == '__main__':
   app = QtWidgets.QApplication([])
   ex = Win()
   ex.show()
   app.exec_()

Answer 1

如果你想要这种行为，你必须使用QButtonGroup ：

from PyQt5 import QtCore, QtGui, QtWidgets

class Win(QtWidgets.QDialog):
    def __init__(self, parent=None):
        super(Win, self).__init__(parent)
        top_layout = QtWidgets.QHBoxLayout()

        top_layout_1 = QtWidgets.QHBoxLayout()
        self.thresh_btns = [QtWidgets.QRadioButton('L1'),
                            QtWidgets.QRadioButton('L2'),
                            QtWidgets.QRadioButton('L3')]
        group_button = QtWidgets.QButtonGroup(self) # <---
        self.thresh_btns[0].setChecked(True)
        for btn in self.thresh_btns:
            top_layout_1.addWidget(btn)
            group_button.addButton(btn)             # <---

        timestamp_groupbox = QtWidgets.QGroupBox('Timestamp')
        top_layout_2 = QtWidgets.QVBoxLayout()
        self.timestamp_current = QtWidgets.QRadioButton('Current')
        self.timestamp_current.setChecked(True)
        self.timestamp_target = QtWidgets.QRadioButton('Last')
        top_layout_2.addWidget(self.timestamp_current)
        top_layout_2.addWidget(self.timestamp_target)
        timestamp_groupbox.setLayout(top_layout_2)

        top_layout.addLayout(top_layout_1)
        top_layout.addWidget(timestamp_groupbox)
        self.setLayout(top_layout)

if __name__ == '__main__':
    import sys
    app = QtWidgets.QApplication(sys.argv)
    ex = Win()
    ex.show()
    sys.exit(app.exec_())