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I would like to get a single message from a topic. Is there a built-in, simple, elegant way to do this? Currently, I am creating a subscriber, and using a threading.Event object to signal when it receives a message, and automatically unregister itself. It works, but it seems unwieldy for a task that I presume to be fairly common.

class SomeClass:
    def __init__(self):
        self.data = None
        self.get_data_subscriber = None
        self.get_data_event = threading.Event()

    def get_data_callback(self, data):
        self.data = data
        self.get_data_subscriber = None

    def run(self):
        rospy.init_node('myNodeName', anonymous=True)

        self.get_data_subscriber = rospy.Subscriber('/sometopic', SomeType, self.get_data_callback)

        while True:
            self.get_data_event.wait(0.1)  # sleep 100ms or wakeup sooner if event was set

            # wait() didn't have a return value until python 2.7, so for compatibility, don't rely on the return val.
            # is_set() method was added in python 2.6, so for compatibility, use isSet() instead.
            if self.get_current_pose_event.isSet():
            if rospy.is_shutdown():

        rospy.loginfo("data is: {}".format(data))

if __name__ == "__main__":
    foo = SomeClass()

Originally posted by rahvee on ROS Answers with karma: 30 on 2018-05-29

Post score: 0


1 Answer 1


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Please see #q270298.

In Python this should be available through rospy.wait_for_message(..) (docs).

Originally posted by gvdhoorn with karma: 86574 on 2018-05-29

This answer was ACCEPTED on the original site

Post score: 6

Original comments

Comment by rahvee on 2018-05-30:
Perfect, thanks!


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