Getting Scala as scripting language to work

dero · August 24, 2015, 4:13pm

Guys,

I am trying to follow https://github.com/openhab/openhab/wiki/Jsr223-Script-Engine to install Scala as a scripting language.

Whatever I tried, I could not make openhab discover the Scala ScriptEngine. What did I wrong?

dero

johannes_stickel · August 27, 2015, 9:17pm

I think it is not possible at the moment. I tried, but it results in a ClassNotFoundException.

I believe - without really understanding the issue yet - it requires only a small change in the add-on. It must initialize the embeddedDefaults setting. This is described here:
http://www.scala-sbt.org/0.13/docs/Faq.html#How+do+I+use+the+Scala+interpreter+in+my+code%3F

A more detailed explanation for the issue can be found here:

gist.github.com

https://gist.github.com/harrah/404272

gistfile1.txt

Proposal: Default compiler/interpreter classpath in a managed environment

The compiler uses a default classpath of 'java.class.path'.  Because many
applications do not use custom class loaders, this default is often sufficient
and no classpath configuration is required.  This is because all jars- the
application and its dependencies, including the Scala compiler and library- are
in 'java.class.path' and the class loader for the application is the same as
that for Scala.

However, it does not work in more complicated setups, including various managed

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dero · August 27, 2015, 10:29pm

Passing a custom classpath through OSGI is next to impossible because OSGI hacks all the classloaders and hooks in bundle resolution.

However, Scala can be installed as a bundle in OSGI and then the ScriptEngineManager needs to find the engines using OSGI resolution. There are some code snippets out there showing that this is quite easy.

But, the main paintpoint of using a scriptengine is rather making scripts work across multiple file (scoping, imports, etc.)…

Dero

marius_kotsbak · January 20, 2017, 1:21pm

Any news here?