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Criando um Pacote ROS

Quick Environment Variable Setup

For this tutorial, you will need to know two key environment variables:

• ROS_ROOT: this is the directory where ROS is installed and contains many ROS-related packages

• ROS_PACKAGE_PATH: this is a of directories that ROS looks to find more ROS packages.

Using roscreate

Before we create a package, let's see how the roscreate-pkg command-line tool works. This creates a new ROS package: manifest, CMakeLists.txt, mainpage.dox, and Makefile. It addresses the common problem of packages being created by hand using pre-existing packages, which leads to errors in build files and manifests.

To create a new package in the current directory:

$ roscreate-pkg pkgname

You can also specify dependencies of that package:

$ roscreate-pkg pkgname depend1 depend2 depend3

Creating a New ROS Package

Now we're going to go into the ros_tutorials directory and create our beginner_tutorials package. We going to make it depend on roscpp and rospy, which are common ROS packages, as well as rospy_tutorials, which has some programs we're going to use later.

$ roscd ros_tutorials
$ roscreate-pkg beginner_tutorials std_msgs rospy roscpp rospy_tutorials roscpp_tutorials turtlesim

You will see:

• Creating package directory ~/ros/ros_tutorials/beginner_tutorials
  Creating include directory ~/ros/ros_tutorials/beginner_tutorials/include/beginner_tutorials
  Creating cpp source directory ~/ros/ros_tutorials/beginner_tutorials/src
  Creating python source directory ~/ros/ros_tutorials/beginner_tutorials/src/beginner_tutorials
  Creating package file ~/ros/ros_tutorials/beginner_tutorials/Makefile
  Creating package file ~/ros/ros_tutorials/beginner_tutorials/manifest.xml
  Creating package file ~/ros/ros_tutorials/beginner_tutorials/CMakeLists.txt
  Creating package file ~/ros/ros_tutorials/beginner_tutorials/mainpage.dox
  
  Please edit beginner_tutorials/manifest.xml and mainpage.dox to finish creating your package

You're going to want to spend some time looking at beginner_tutorials/manifest.xml. manifests play an important role in ROS as they define how Packages are built, run, and documented.

Now lets make sure that ROS can find your new package:

$ rospack find beginner_tutorials 

• ~/ros/ros_tutorials/beginner_tutorials

Try moving to the directory for the package.

$ roscd beginner_tutorials 
$ pwd

• ~/ros/ros_tutorials/beginner_tutorials

First-order package dependencies

Some depencancies where provided earlier to roscreate-pkg. These first-order dependencies can be provided by the rospack tool.

$ rospack depends1 beginner_tutorials 

• std_msgs
  rospy
  roscpp
  rospy_tutorials
  roscpp_tutorials
  turtlesim

These are the same dependencies that were specified when using roscreate-pkg. This dependencies for a package are stored in the manifest file. Take a look at the manifest file.

$ roscd beginner_tutorials
$ cat manifest.xml

• <package>
  
  ...
  
    <depend package="std_msgs"/>
    <depend package="rospy"/>
    <depend package="roscpp"/>
    <depend package="rospy_tutorials"/>
    <depend package="roscpp_tutorials"/>
    <depend package="turtlesim"/>
  
  </package>

Indirect package dependencies

In many cases a dependency will also have its own dependencies. For instance rospy has some dependencies.

$ rospack depends1 rospy

• roslib
  roslang

A package can have quite a few indirect dependencies. Luckily rospack can recursively determine all nested dependencies.

$ rospack depends beginner_tutorials

• enmsg_cpp
  roslib
  std_msgs
  roslang
  rospy
  xmlrpc++
  rosconsole
  roscpp
  pycrypto
  paramiko
  rosout
  roslaunch
  rostest
  std_srvs
  roscpp_tutorials
  rospy_tutoria

Now that you've made a new ROS package, let's create a ROS msg and srv.