get_or_create a widget instance

get_or_create.py

    def __init__(self):
        item = gtk.MenuItem("Manage Services")
        menu.append(item)
        item.connect('activate', self.get_or_create_widget('services'))

    def get_or_create_widget(self, widget_name):
        widget_name = '%s_dialog' % widget_name
        if hasattr(self, widget_name):
            return lambda cb: getattr(self, widget_name).show()
        return getattr(self, 'create_%s' % widget_name)