Rename M3 property id -> key

[enikao]

As discussed in meeting on 2023-03-03, we'll rename M3 NamespacedEntity.id to NamespacedEntity.key and Metamodel.id to Metamodel.key.

Rationale: Clearly separate node ids (#31) from meta-links (#89).

[dslmeinte]

I thought the key was going to be an extra key. If it's a renaming we're violating the “M2s are also (just) models” principle.

[ftomassetti]

I think this is an extra key: M3 elements will still have the id as all nodes. At the moment they both have the "natural" Node ID and also a property called "id". We are rename that latter property to key, and keeping the Node.ID.

[joswarmer]

I think this is an extra key: M3 elements will still have the id as all nodes. At the moment they both have the "natural" Node ID and also a property called "id". We are rename that latter property to key, and keeping the Node.ID.

What do you mean my "natural node id"? Isn't that just the "id" property?

[ftomassetti]

What do you mean my "natural node id"? Isn't that just the "id" property?

A Node has a field id defined in the interface of Node. In addition to that it has properties, one of which may be called id.

Given all M3 elements extends Node, they had this id common to all nodes, and in addition to that some defined a property named id. So that was extremely confusing and this is way we are now renaming the property id to key, while keeping the Node.id with the current name

[ftomassetti]

Should we create an interface for things that have a Key? It would be implemented by Metamodel and MetamodelElement

[dslmeinte]

Should we create an interface for things that have a Key? It would be implemented by Metamodel and MetamodelElement

We probably should, although for the TS-impl. it seems to be sufficient to adapt M3Node.

I'm still not sure whether renaming id → key is the right thing to do, or to just add key, though. Not having an id breaks the assumption of a metamodel also being just a model of Nodes with every Node having an id.

[ftomassetti]

I think that every node would still have an id, I think at some point they had the id, as all nodes, and they had a property also called id. I think that is being renamed to key, while still keeping the Node.id, for all nodes including metamodel elements

[enikao]

I agree with Federico: Conceptually, id is an inherent "piece of information" of any node -- similar to the memory address of an object in C++. We're renaming the explicitly named property id to key, exactly to avoid that mix-up.