text: #!/usr/bin/env python
  # Software License Agreement (BSD License)
  #
  # Copyright (c) 2008, Willow Garage, Inc.
  # All rights reserved.
  #
  # Redistribution and use in source and binary forms, with or without
  # modification, are permitted provided that the following conditions
  # are met:
  #
  #  * Redistributions of source code must retain the above copyright
  #    notice, this list of conditions and the following disclaimer.
  #  * Redistributions in binary form must reproduce the above
  #    copyright notice, this list of conditions and the following
  #    disclaimer in the documentation and/or other materials provided
  #    with the distribution.
  #  * Neither the name of Willow Garage, Inc. nor the names of its
  #    contributors may be used to endorse or promote products derived
  #    from this software without specific prior written permission.
  #
  # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  # COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  # POSSIBILITY OF SUCH DAMAGE.
  #
  # Revision $Id: listener.py 5263 2009-07-17 23:30:38Z sfkwc $
  
  ## Simple talker demo that listens to std_msgs/Strings published 
  ## to the 'chatter' topic
  
  import rospy
  from std_msgs.msg import String
  
  def param_talker():
      rospy.init_node('param_talker')
  
      # Fetch values from the Parameter Server. In this example, we fetch
      # parameters from three different namespaces:
      #
      # 1) global (/global_example)
      # 2) parent (/foo/utterance)
      # 3) private (/foo/param_talker/topic_name)
  
      # fetch a /global parameter
      global_example = rospy.get_param("/global_example")
      rospy.loginfo("%s is %s", rospy.resolve_name('/global_example'), global_example)
      
      # fetch the utterance parameter from our parent namespace
      utterance = rospy.get_param('utterance')
      rospy.loginfo("%s is %s", rospy.resolve_name('utterance'), utterance)
      
      # fetch topic_name from the ~private namespace
      topic_name = rospy.get_param('~topic_name')
      rospy.loginfo("%s is %s", rospy.resolve_name('~topic_name'), topic_name)
  
      # fetch a parameter, using 'default_value' if it doesn't exist
      default_param = rospy.get_param('default_param', 'default_value')
      rospy.loginfo('%s is %s', rospy.resolve_name('default_param'), default_param)
      
      # fetch a group (dictionary) of parameters
      gains = rospy.get_param('gains')
      p, i, d = gains['P'], gains['I'], gains['D']
      rospy.loginfo("gains are %s, %s, %s", p, i, d)    
  
      # set some parameters
      rospy.loginfo('setting parameters...')
      rospy.set_param('list_of_floats', [1., 2., 3., 4.])
      rospy.set_param('bool_True', True)
      rospy.set_param('~private_bar', 1+2)
      rospy.set_param('to_delete', 'baz')
      rospy.loginfo('...parameters have been set')
  
      # delete a parameter
      if rospy.has_param('to_delete'):
          rospy.delete_param('to_delete')
          rospy.loginfo("deleted %s parameter"%rospy.resolve_name('to_delete'))
      else:
          rospy.loginfo('parameter %s was already deleted'%rospy.resolve_name('to_delete'))
  
      # search for a parameter
      param_name = rospy.search_param('global_example')
      rospy.loginfo('found global_example parameter under key: %s'%param_name)
      
      # publish the value of utterance repeatedly
      pub = rospy.Publisher(topic_name, String, queue_size=10)
      while not rospy.is_shutdown():
          pub.publish(utterance)
          rospy.loginfo(utterance)
          rospy.sleep(1)
          
  if __name__ == '__main__':
      try:
          param_talker()
      except rospy.ROSInterruptException: pass
      
  