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--- doc:beginner:package_for_turtlesim [2014/03/12 14:31] – simplified text hmess
+++ doc:beginner:package_for_turtlesim [2015/05/11 16:55] (current) – removed gkazhoya
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-====== Creating a CRAM package ======
-**Description:** In this tutorial you will set up a ROS package to use the CRAM plan language within the lisp repl.
-**Next Tutorial:** [[doc:beginner:controlling_turtlesim_2|Controlling turtlesim from Lisp_2]]
-===== Creating a ROS package =====
-First we need to create a ROS package that depends on ''cram_language''.
-You can do this with either catkin or rosbuild. On the Ros website there are two tutorials about creating a package: [[http://wiki.ros.org/catkin/Tutorials/CreatingPackage|Package creation]] and [[http://wiki.ros.org/ROS/Tutorials/Creating%20a%20Package%20by%20Hand|Package creation by hand]]. It is recommended that you work with catkin.
-In the ''src'' subdirectory of your catkin workspace execute the following command:
-<code bash>$ catkin_create_pkg cram_beginner_tutorial cram_language </code>
-If you have good reasons you can also follow the rosbuild instructions to create a package.
-===== Setting up the Lisp infrastructure =====
-Setting up the Common Lisp part is a little bit more work. First we need to create a Lisp 'project file', i.e. an ASDF system.
-After that we will need to create a Common Lisp package (i.e. the equivalent to C++ namespaces). You can learn roslisp in more detail at the [[http://wiki.ros.org/roslisp/Tutorials/BasicUsage|roslisp tutorial]]
-==== Creating an ASDF system ====
-Switch into the root directory of the ''cram_beginner_tutorial'' package
-and create a file ''cram-beginner-tutorial.asd''. You shouldn't use underscores but dashes in .asd file names. The reason is that the system that is defined in the .asd file should be named like the file itself and in Lisp it is very uncommon to use underscores in general.
-Put the following content into ''cram-beginner-tutorial.asd'':
-<code lisp>
-(defsystem cram-beginner-tutorial
-  :depends-on (cram-language)
-  :components
-  ((:module "src"
-            :components
-            ((:file "package")
-             (:file "tutorial" :depends-on ("package"))))))
-</code>
-The first line defines the name of the system. Then we specify the dependencies of the system, i.e. other systems that need to be loaded before we load our system.
-Finally, we define the components of the system. A component is a sort of sub-system and might be either a module (i.e. a sub-directory) or a file. ASDF knows some more component types but they are not relevant for us most of the time. We define that the system knows a sub-directory ''src''. Further, we define that this module contains two components, one file for the package definition ''package.lisp'' and one with the actual tutorial code ''tutorial.lisp'' that has exactly one dependency - the component ''package''. We will create these two source files next. Dependencies inside the system can be any component that is known in the current scope. That means that a component can only depend on those components that are defined in the same parent component. Please note that the file extension must be left out when defining files.
-==== Creating the Lisp Package ====
-Lisp packages are the equivalent to C++ namespaces or to Python modules. Lisp packages cannot be hierarchic. We can define which other packages should be used, i.e. which symbols should be accessible without a package prefix. Further, we can define which symbols should be exported from the package.
-Create a sub-directory ''src'' in your package. Then create the file ''package.lisp'' and put the following code into it:
-<code lisp>
-(defpackage cram-beginner-tutorial
-  (:nicknames :tut)
-  (:use #:cpl))
-</code>
-We define a package with the name ''cram-beginner-tutorial''. Packages in Common Lisp can have an arbitrary number of nicknames. In our case we nickname ''cram-beginner-tutorial'' as ''tut''. Finally, we define that the package uses another package ''cpl'' which is a nickname of the package  ''CRAM Plan Language''.
-==== Exporting the ASDF system to ROS ====
-To actually load the ASDF system, all files referenced in the system definition must be present and we are missing the file ''tutorial.lisp'' in ''src'', so create it with the following content:
-<code lisp>
-(in-package :tut)
-</code>
-This just selects the namespace of the file by the nickname '':tut'' we defined in ''package.lisp''. We will fill it with more content in later tutorials.
-Now we are ready to compile and load our new system. Launch the Lisp REPL.
-Then load your newly created system by typing:
-<code lisp>
-(ros-load:load-system "cram_beginner_tutorial" :cram-beginner-tutorial)
-</code>
-This loads the ''cram-beginner-tutorial'' of the package ''cram_beginner_tutorial''.
-Test it by evaluating
-<code lisp>
-(in-package :tut)
-</code>
-Now that we have created our first CRAM package, let's try controlling the ROS turtlesim from it...
-[[doc:beginner:controlling_turtlesim_2|Controlling turtlesim from Lisp_2]]