Keep namespace relative if base_prefix is empty string #40
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Suppose that rather than give a different string for the base_prefix, a user wishes to entirely remove the base prefix. If the param base_prefix is set to the empty string, then previously the topic names would become absolute, i.e., would begin with "/". This changeset ensures that they remain relative in this case.
| @@ -309,6 +309,8 @@ void GazeboRosKobuki::setupRosApi(std::string& model_name) | |||
| { | |||
| std::string base_prefix; | |||
| gazebo_ros_->node()->param("base_prefix", base_prefix, std::string("mobile_base")); | |||
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I believe the default value std::string("mobile_base") has to be dropped. Otherwise you won't be able to set the base_prefix to be an empty string.
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If the parameter server has the empty string as the value of "base_prefix", then ros::NodeHandle::param() will use it and not the default. The API description of param() claims that the default value is only used if the parameter value cannot be retrieved.
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You are right in case of the ROS parameter server, but this is not the case here. The parameter here comes from Gazebo and is set here: https://github.com/yujinrobot/kobuki_desktop/blob/indigo/kobuki_gazebo/launch/includes/robot.launch.xml#L9
If I provide an empty string, I believe the parameter is considered not set and the default is selected. At least this happend when I tried it. How did you make it work?
Suppose that rather than use
base_prefixto change the default of "mobile_base", auser wishes to entirely remove the base prefix. If the param
base_prefixis set to the empty string, then the topic nameswould become absolute, i.e., would begin with "/". This changeset
ensures that they remain relative in this case.
The motivating use-case is spawning multiple instances of the Kobuki model, each with a unique namespace, while trying to keep topic names short.