import sys

from PyQt4 import QtCore, QtGui

class MainWindow(QtGui.QWidget):

    def __init__(self, parent = None):

        QtGui.QWidget.__init__(self, parent)

        self.setWindowTitle('emit')

        self.resize(250, 150)

        # 创建一个新的信号closeEmitApp()，该信号在按下鼠标事件发生时被发射

        self.connect(self, QtCore.SIGNAL('closeEmitApp()'), QtCore.SLOT('close()'))

        # 使用connect函数将手动创建的closeEmitApp()信号和程序的close()槽函数连接起来。这样在用户按下鼠标的任意键时，程序就会结束。

    def mousePressEvent(self, event):

        self.emit(QtCore.SIGNAL('closeEmitApp()'))  #使用PyQt内建的emit函数发射信号closeEmitApp()

app = QtGui.QApplication(sys.argv)

main = MainWindow()

main.show()

sys.exit(app.exec_())