try_get_topic_class.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-
"""
Created on 6/16/15

@author: Sammy Pfeiffer

try_get_topic_class.py contains a little test
demonstrating that get_topic_class from rostopic
does not give the original name of a topic given a
topic string of a subfield
"""


import rospy
from rostopic import get_topic_class
from geometry_msgs.msg import PoseStamped

TESTING_TOPIC = '/posestamped'

if __name__ == '__main__':
    rospy.init_node('test_get_topic_class', anonymous=True)

    # First we need a publisher that publishes some class that has subfields
    # I like PoseStamped, as it has a header and also some subfields
    ps_pub = rospy.Publisher(TESTING_TOPIC, PoseStamped, queue_size=1, latch=True)

    # We need it publishing, so lets publish, and check if get_topic_class correctly
    # gives us the topic name as it's docstring states:
    #   Get the topic message class
    #   :returns: message class for topic, real topic
    #   name, and function for evaluating message objects into the subtopic

    # Publish a message
    ps_pub.publish(PoseStamped())
    # Wait for some time to let the universe get comfy
    rospy.sleep(0.1)


    # Let's check the "real topic", after the print line you can see the output given
    _, real_topic, _ = get_topic_class(TESTING_TOPIC)
    print "get_topic_class says real_topic of '" + TESTING_TOPIC + "' is: '" + real_topic + "'"
    # get_topic_class says real_topic of '/posestamped' is: '/posestamped'

    SUBFIELD_HEADER = TESTING_TOPIC + '/header'
    _, real_topic, _ = get_topic_class(SUBFIELD_HEADER)
    print "get_topic_class says real_topic of '" + SUBFIELD_HEADER + "' is: '" + real_topic + "'"
    # get_topic_class says real_topic of '/posestamped/header' is: '/posestamped/header'

    SUBFIELD_POSE = TESTING_TOPIC + '/pose'
    _, real_topic, _ = get_topic_class(SUBFIELD_POSE)
    print "get_topic_class says real_topic of '" + SUBFIELD_POSE + "' is: '" + real_topic + "'"
    # get_topic_class says real_topic of '/posestamped/pose' is: '/posestamped/pose'

    SUBFIELD_POSE_POSITION = TESTING_TOPIC + '/pose/position'
    _, real_topic, _ = get_topic_class(SUBFIELD_POSE_POSITION)
    print "get_topic_class says real_topic of '" + SUBFIELD_POSE_POSITION + "' is: '" + real_topic + "'"
    # get_topic_class says real_topic of '/posestamped/pose/position' is: '/posestamped/pose'

    SUBFIELD_POSE_POSITION_X = TESTING_TOPIC + '/pose/position/x'
    _, real_topic, _ = get_topic_class(SUBFIELD_POSE_POSITION_X)
    print "get_topic_class says real_topic of '" + SUBFIELD_POSE_POSITION_X + "' is: '" + real_topic + "'"
    # get_topic_class says real_topic of '/posestamped/pose/position/x' is: '/posestamped/pose'

    # Leaving the process open for debugging purposes
    rospy.spin()