Using Lua as a state machine

[amaroyo]

Hey guys! @vtikha

Are you still using Lua in yarp? I wanted to create a state machine in which, in different states it could send and receive information/commands from different modules. Do you recommend me to use Lua? Or is there something else which is better?

Thanks a lot!
Alex.

[pattacini]

Hi @amaroyo

Yep, I can confirm that using Lua is still our preferable way to code not only state machines but also behavior based applications within our infrastructure.

cc @vtikha @apaikan

[jgvictores]

Hi @amaroyo @pattacini @vtikha @apaikan !!

Disclaimer: no intention to go against any recommended best practice! Will begin Thinking in Lua asap! 😉

The robotic video-game I'm involved in is currently written in C/C++. Facts are we actually made a small state machine library for it (with some limited documentation and tests), and are going to present it at an upcoming workshop. Feel free to take a look, reuse, and/or file an issue if you see anything worthy of comment. Regarding code integration (for not having to install the video-game as a dependency), I've spoken with other project leaders and we have the intention of splitting several projects into mini-repositories and then unifying them through git submodules. We could give priority to this library if required.

[pattacini]

No problem @jgvictores, you're very welcome to advertise new solutions you're working on 😄.

Side note

Aiming to mini-repositories is a good way of organizing code and its dependencies, but using git submodules is discouraged, at least in our view; see discussion in robotology/icub-main#360.

By the way, why don't you try our superbuild mechanism instead?

cc @drdanz

[jgvictores]

@pattacini I was actually quite reluctant to git submodules, which is in part why we haven't been doing it more. Thanks for the pointer to the superbuild mechanism, I'll comment on there if I have any doubts!!

[pattacini]

@jgvictores that's good!

@amaroyo I've found this resource online: http://wiki.icub.org/images/4/46/Rfsm_yarp.pdf.
@apaikan do you have better locations where to point at?

[apaikan]

@pattacini thanks for sharing the tutorial. I guess that is the only tutorial using yarp with rfsm.

@amaroyo honestly, I do not see any special need for other doc or tutorials regarding rFSM and Lua.

What actually one needs is just to know:

• how to compile yarp-lua binding and use yarp from Lua.
• how to write state machines using rFSM.

@jgvictores there are plenty reasons why we decided to stay away from c++-implemented or pure xml-based state machines (e.g., SCXML). Using scripting for developing state machines for component coordination has distinct advantages as thoroughly discussed in this article.

[amaroyo]

@jgvictores Thanks, I will take a look to the code!

@pattacini Yes! I found the same slides in google, but I saw that the date was 2013 :)

@apaikan Thanks for the documentation, I will take them a look and tell you how it goes!