NewModule

How to create a new module?

The goal of this tutorial is to create a new module to be used in cs::APEX.

The package you are going to create will be in the main catkin workspace, if you are an experienced catkin user, you can also use another workspace.

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Next Tutorial: How to create a new node?

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Open a terminal and navigate to your catkin workspace where you cloned cs::APEX.

$ cd $WS/src/csapex/

Plugin packages can be built in any catkin workspace. For now we assume, that plugins are in the subdirectory plugins, which contains a few bash scripts that are helpful for maintance.

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We are now creating a new package called csapex_tutorial:

$ cd plugins
$ catkin_create_pkg csapex_tutorial csapex csapex_opencv

Which tells catkin that our package is dependent upon csapex and csapex_opencv (for image message support) and will produce output like

Created file csapex_tutorial/CMakeLists.txt
Created file csapex_tutorial/package.xml
Successfully created files in .../src/csapex_tutorial. Please adjust the values in package.xml.

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Next we take a look at the meta files:

cd csapex_tutorial
gedit package.xml

Here we provide all necessary information (See the catkin tutorials). When you are finished, you need to export a list of all provided plug-ins. Therefore we add an export to package.xml:

  <export>
    <csapex plugin="${prefix}/plugins.xml" />
  </export>

Which tells cs::APEX, in which file to look for plug-ins.

Next we create the file where we tell the plug-in system to use a dynamic library called libcsapex_tutorial, which we will create in the next tutorial

echo '<library path="libcsapex_tutorial"></library>' > plugins.xml

We also need to install this file using catkin. This is achieved by adding

install(FILES plugins.xml
        DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}) 

to CMakeLists.txt.

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At last we create a directory for our source code to be compliant to the convention. This is were all your code should go:

mkdir src

Now we can test if everything went okay by invoking catkin_make:

cd $WS
catkin_make

and verifying that csapex_tutorial is listed under the list of all packages

-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- ~~  traversing xxx packages in topological order:
..
-- ~~  - csapex_tutorial
..

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In the next tutorial we are going to create a new node