机制1：
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#!/usr/bin/env python
import sys

from PyQt4 import QtGui, uic

app = QtGui.QApplication(sys.argv)
widget = uic.loadUi("demo.ui")
widget.show()
app.exec_()


机制2：
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#!/usr/bin/env python
import sys

from PyQt4 import QtCore, QtGui, uic

class DemoImpl(QtGui.QDialog):
def __init__(self, *args):
QtGui.QWidget.__init__(self, *args)
uic.loadUi("demo.ui", self)

@QtCore.pyqtSignature("")
def on_button1_clicked(self):
for s in "This is a demo".split(" "):
self.list.addItem(s)

app = QtGui.QApplication(sys.argv)
widget = DemoImpl()
widget.show()
app.exec_()