python - 关闭对话框时出现什么错误

Question

我刚刚开始学习 PyQt，我有一个小应用程序，它似乎工作正常，我点击对话框右上角的 X 将其关闭。当我这样做并返回到控制台时，我看到出现了如下异常:

To exit: use 'exit', 'quit', or Ctrl-D.
An exception has occurred, use %tb to see the full traceback.

SystemExit: 0


In [2]: %tb
Traceback (most recent call last):

  File "<ipython-input-1-4524246fa84a>", line 1, in <module>
    runfile('C:/Users/21025/simpleAdder.pyw', wdir='C:/Users/21025')

  File "C:\Users\21035\AppData\Local\Continuum\Anaconda\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py", line 586, in runfile
    execfile(filename, namespace)

  File "C:/Users/21035/simpleAdder.pyw", line 81, in <module>
    sys.exit(app.exec_())

SystemExit: 0

我做错了什么？应用代码如下所示:

from PyQt4 import QtCore, QtGui

try:
    _fromUtf8 = QtCore.QString.fromUtf8
except AttributeError:
    def _fromUtf8(s):
        return s

try:
    _encoding = QtGui.QApplication.UnicodeUTF8
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig, _encoding)
except AttributeError:
    def _translate(context, text, disambig):
        return QtGui.QApplication.translate(context, text, disambig)

class Ui_Dialog(object):
    def setupUi(self, Dialog):
        Dialog.setObjectName(_fromUtf8("Dialog"))
        Dialog.resize(673, 565)
        self.v1Input = QtGui.QLineEdit(Dialog)
        self.v1Input.setGeometry(QtCore.QRect(50, 70, 71, 20))
        self.v1Input.setObjectName(_fromUtf8("v1Input"))
        self.v2Input = QtGui.QLineEdit(Dialog)
        self.v2Input.setGeometry(QtCore.QRect(150, 70, 71, 20))
        self.v2Input.setObjectName(_fromUtf8("v2Input"))
        self.v3Input = QtGui.QLineEdit(Dialog)
        self.v3Input.setGeometry(QtCore.QRect(250, 70, 71, 20))
        self.v3Input.setObjectName(_fromUtf8("v3Input"))
        self.calc_result = QtGui.QLineEdit(Dialog)
        self.calc_result.setGeometry(QtCore.QRect(420, 70, 113, 20))
        self.calc_result.setObjectName(_fromUtf8("calc_result"))
        self.label = QtGui.QLabel(Dialog)
        self.label.setGeometry(QtCore.QRect(60, 50, 46, 13))
        self.label.setObjectName(_fromUtf8("label"))
        self.label_2 = QtGui.QLabel(Dialog)
        self.label_2.setGeometry(QtCore.QRect(160, 50, 46, 13))
        self.label_2.setObjectName(_fromUtf8("label_2"))
        self.label_3 = QtGui.QLabel(Dialog)
        self.label_3.setGeometry(QtCore.QRect(260, 50, 46, 13))
        self.label_3.setObjectName(_fromUtf8("label_3"))
        self.label_4 = QtGui.QLabel(Dialog)
        self.label_4.setGeometry(QtCore.QRect(450, 50, 46, 13))
        self.label_4.setObjectName(_fromUtf8("label_4"))
        self.pushButton = QtGui.QPushButton(Dialog)
        self.pushButton.setGeometry(QtCore.QRect(200, 230, 75, 23))
        self.pushButton.setObjectName(_fromUtf8("pushButton"))

        self.retranslateUi(Dialog)
        QtCore.QObject.connect(self.pushButton, QtCore.SIGNAL(_fromUtf8("clicked()")), self.v1Input.clear)
        QtCore.QObject.connect(self.pushButton, QtCore.SIGNAL(_fromUtf8("clicked()")), self.v2Input.clear)
        QtCore.QObject.connect(self.pushButton, QtCore.SIGNAL(_fromUtf8("clicked()")), self.v3Input.clear)
        QtCore.QMetaObject.connectSlotsByName(Dialog)


    def retranslateUi(self, Dialog):
        Dialog.setWindowTitle(_translate("Dialog", "Dialog", None))
        self.label.setText(_translate("Dialog", "Val 1", None))
        self.label_2.setText(_translate("Dialog", "Val 2", None))
        self.label_3.setText(_translate("Dialog", "Val 3", None))
        self.label_4.setText(_translate("Dialog", "Result", None))
        self.pushButton.setText(_translate("Dialog", "Clear Inputs", None))       


if __name__ == "__main__":
    import sys
    app = QtGui.QApplication(sys.argv)
    Dialog = QtGui.QDialog()
    ui = Ui_Dialog()
    ui.setupUi(Dialog)
    Dialog.show()
    sys.exit(app.exec_())

Answer 1

如消息所示，代码包含 sys.exit(app.exec_())，它将执行 GUI，然后调用退出例程。您是从交互式提示中调用它的，因此它没有退出，而是通知您您试图从您调用的对象中退出。如果您希望能够从交互式提示中调用此代码而不会出现错误，只需删除退出部分，将 sys.exit(app.exec_()) 更改为 app.exec_( )。