00001 #!/usr/bin/env python 00002 # Software License Agreement (BSD License) 00003 # 00004 # Copyright (c) 2008, Willow Garage, Inc. 00005 # All rights reserved. 00006 # 00007 # Redistribution and use in source and binary forms, with or without 00008 # modification, are permitted provided that the following conditions 00009 # are met: 00010 # 00011 # * Redistributions of source code must retain the above copyright 00012 # notice, this list of conditions and the following disclaimer. 00013 # * Redistributions in binary form must reproduce the above 00014 # copyright notice, this list of conditions and the following 00015 # disclaimer in the documentation and/or other materials provided 00016 # with the distribution. 00017 # * Neither the name of Willow Garage, Inc. nor the names of its 00018 # contributors may be used to endorse or promote products derived 00019 # from this software without specific prior written permission. 00020 # 00021 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 00022 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 00023 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 00024 # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 00025 # COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 00026 # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 00027 # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 00028 # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 00029 # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 00030 # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 00031 # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 00032 # POSSIBILITY OF SUCH DAMAGE. 00033 # 00034 # Revision $Id$ 00035 00036 ## Simple listener demo that demonstrates how to register additional 00037 ## arguments to be passed to a subscription callback 00038 00039 NAME = 'listener_with_user_data' 00040 00041 import sys 00042 00043 import rospy 00044 from std_msgs.msg import * 00045 00046 def callback(data, args): 00047 if args == 1: 00048 print "#1: I heard [%s]"%data.data 00049 elif args == 2: 00050 print "#2: I heard [%s]"%data.data 00051 else: 00052 print "I heard [%s] with userdata [%s]"%(data.data, str(args)) 00053 00054 def listener_with_user_data(): 00055 # Callback arguments (aka user data) allow you to reuse the same 00056 # callback for different topics, or they can even allow you to use 00057 # the same callback for the same topic, but have it do something 00058 # different based on the arguments. 00059 rospy.Subscriber("chatter", String, callback, 1) 00060 rospy.Subscriber("chatter", String, callback, 2) 00061 rospy.Subscriber("chatter", String, callback, ("chatter1", 4)) 00062 rospy.Subscriber("chatter2", String, callback, "This is from chatter2") 00063 rospy.init_node(NAME, anonymous=True) 00064 rospy.spin() 00065 00066 if __name__ == '__main__': 00067 try: 00068 listener_with_user_data() 00069 except KeyboardInterrupt, e: 00070 pass 00071 print "exiting"