Automatically validate project when a metamodel in the ALE environment changes

[echebbi]

Motivation

Validators are only triggered when making changes in the editor. However, adding/removing/renaming a class/method/attribute to/from a metamodel should also trigger a new validation.

Proposed Solution

Detect when the a metamodel changes and programmatically trigger a new Xtext validation every time.

Proposed Implementation

Not sure about the best implementation; I see two possibilities:

• use a couple resource/preferences listeners
• use a project builder.

[dvojtise]

the metamodel (ie. ecore file) is probably in another project, you'll need a workspace listener in order to detect changes

It will need to be carefully filtered in order to not trigger computation too often

https://www.eclipse.org/articles/Article-Resource-deltas/resource-deltas.html

about were the build should be done, I usually prefer a builder because it is convenient for a user to do a "clean all" in order to launch all validations and compilations (a couple of resource/preference listener doesn't allow that)