Cannot access members of NodeIds and StatusCodes from a Scala environment

[an-nie]

Hi!

We're using milo in a Scala 2.12.19 environment. We're upgrading from stack-core, sdk-client 0.6.8 to milo-stack-core, milo-sdk-client 1.1.0 and have encountered a problem with the classes NodeIds and StatusCodes.

import org.eclipse.milo.opcua.stack.core.StatusCodes
import org.eclipse.milo.opcua.stack.core.NodeIds

val node = NodeIds.ObjectsFolder              // does not compile
val code = StatusCodes.Bad_UserAccessDenied   // does not compile

In Scala, accessing inherited static members of parent classes like NodeIds0, NodeIds1, ... is not possible. This is a feature as described here.

Generally, the workaround seems to be to import the parent classes, but NodeIds0, ... are package-private and thus not accessible.

Is there a recommended way around this problem in milo for Scala developers?

[kevinherron]

I don’t have any recommendations other than creating your own application level objects containing only the NodeId and StatusCode constants you need/use, but I can look at changing the visibility on the inherited classes as well.

[an-nie]

It's a shame they had to be split into multiple classes in the first place, but the amount of NodeIds and StatusCodes grew beyond what the JVM would compile in a single class.

When you put it like that, seeing how the inheritance structure already is a solution to an uninteresting problem, copying the classes into our project and changing the signatures doesn't seem quite so brutally pedestrian anymore. That way we can use the IDE autocompletion. I will do that for now and keep an eye on the project in the meantime.

[kevinherron]

@an-nie can you verify this change actually does something towards making it usable in Scala? #1687

[an-nie]

It works:

I've only stumbled across this pattern with NodeIds and StatusCodes, but are there other instances in the project?

[kevinherron]

I think these are the only instances of this.

[an-nie]

Great!
Thank you again for your quick help!