Introduction

This is a simple helper-package for loading variables from the parameter server.

The main idea is to simplify the handling of parameters, which can be set to default values. The load() function will print if a parameter is loaded from the server or if its default value is used. In each case, the final value is printed, too.

Node

rosrun parameter_pa parameter_pa_node

roslaunch parameter_pa parameter_pa.launch

Services:

Service Name	Type	Description
"~/substitutePath"	parameter_pa/ParameterPaString	Replaces each "$(find xyz)" with the corresponding path - this is similar to calling loadPath().
"~/substituteRessource"	parameter_pa/ParameterPaString	Resolves ressource name - this is similar to calling loadTopic().

Functions

The main load() function can handle bool, int, double and string - all as single values and as vectors. Also matrices of double (float) can be loaded.

Additionaly, there are two more dedicated load functions: loadPath() and loadTopic(). Both are basically loading a simple string from the parameter server as descript above. Furthermore the strings are specificly manipulated:

loadPath()

Every "$(find xyz)" will be replaced with the path of package xyz.

loadTopic()

Names are resolved with additional operators.

For these examples assume that ROS_NAMESPACE is set to "/name/space" and that the nodes' name is "parameter_pa_node"

Regular ressource names

in_string	out_string	comment
ressource	ressource	relative name
ressource/	ressource/	relative name ending with slash
ns/ressource	ns/ressource	relative name with namespace
ns/ressource/	ns/ressource/	relative name with namespace ending with slash
/ressource	/ressource	absolute name
/ressource/	/ressource/	absolute name ending with slash
/ns/ressource	/ns/ressource	absolute name with namespace
/ns/ressource/	/ns/ressource/	absolute name with namespace ending with slash

Private ressource names

in_string	out_string	comment
~	/name/space/parameter_pa_node	private namespace
~/	/name/space/parameter_pa_node/	private namespace ending with slash
~/ressource	/name/space/parameter_pa_node/ressource	private namespace with relative name
~/ns/ressource/	/name/space/parameter_pa_node/ns/ressource/	private namespace with relative name and relative namespace ending in slash
/abc/~/xyz	Error	no private namespace within absolute name allowed

Locale ressource names

in_string	out_string	comment
.	/name/space	local namespace
./	/name/space/	local namespace ending with slash
./ressource/	/name/space/ressource/	local namespace with relative name ending in slash
./ns/ressource	/name/space/ns/ressource	local namespace with relative name and relative namespace
/abc/./xyz	/abc/xyz	local namespace within absolute name

Previous ressource names

in_string	out_string	comment
..	/name	previous namespace
../	/name/	previous namespace ending with slash
../ressource/	/name/ressource/	previous namespace with relative name ending in slash
../ns/ressource	/name/ns/ressource	previous namespace with relative name and relative namespace
/abc/def/../xyz	/abc/xyz	previous namespace within absolute name

Removal of double slashes

in_string	out_string	comment
ressource//	ressource/	relative name ending with slash
//ns/ressource	/ns/ressource	absolute name with namespace

More examples

in_string	out_string
~/abc/.//def/../ns//ressource/	/name/space/parameter_pa_node/abc/ns/ressource/
ns//.././..//ressource	/name/space/ressource
../../../../../../ressource/	/ressource/

Example Usage

A typical output looks like this:

[ INFO] [1499357951.543886548]: load parameter ~/tf_lookup_time (0.1)
[ INFO] [1499357951.544331412]: parameter ~/buffer_pointcloud not set (defaults to false)
[ INFO] [1499357951.544867951]: load parameter ~/debugging (true)

Here is the related source code, which is taken from pcdfilter_pa:

cParameterPaRos paramloader;
 
// ...
paramloader.load("~/tf_lookup_time"   , filters_.tf_lookup_time_     );
paramloader.load("~/buffer_pointcloud", rosparams_.buffer_pointcloud_);
paramloader.load("~/debugging"        , rosparams_.debugging_        );

Links and packages

Source code at github

https://github.com/TUC-ProAut/ros_parameter

ROS packages

ros-kinetic-parameter-pa

ros-melodic-parameter-pa _(upcoming)_

ros-noetic-parameter-pa _(upcoming)_

ROS Build-Status and Documentation

ROS-Distribution	Build-Status	Documentation
Indigo	EOL April 2019	docs.ros.org/indigo
Jade	EOL May 2017	docs.ros.org/jade
Kinetic	EOL April 2021	docs.ros.org/kinetic
Lunar	EOL May 2019	docs.ros.org/lunar
Melodic		docs.ros.org/melodic
Noetic		docs.ros.org/noetic