[qvtd-dev] Xtext nature

[Ed Willink <ed@xxxxxxxxxxxxx>]

Hi

The imports from *.xtext files have been a consistent problem.

Originally they were import 'platform:/resource/....' and that was fine 
in Xtext 2.3 but became solid warnings later.

On investigation it was because Xtext required import 'http:/...' so we 
switched and the warnings went away but reappeared as intermittent 
metamodel schizophrenia errors.

Xtext 2.8.0 introduces a 
"org.eclipse.xtext.grammar.InvalidPackageReference.external" preference 
that can now be set to 'ignore' so that we can revert back to import 
'platform:/resource/....' and get no warnings.

I've been using this for a couple of days and no warnings/no errors. 
Back to where we were with Xtext 2.3.

Now that imports are direct there is no need for the Xtext indexer to 
search all *.ecore's and everything else it can find to come up with an 
intermittently wrong answer. The Xtext nature has been removed from 
nearly all plugins.

Minor irritation: you will get a "Do you want to add the Xtext nature" 
pop-up the first time you open each *.xtext file. Answer No, checking 
the don't ask again box. We do not need the Xtext indexer to waste build 
resources. I've requested a no-pop-up preference.

I think that we only need the Xtext nature in plugins with *.mwe2 or 
*.xtend files.

Adolfo: you might care to try removing the Xtext nature from some of 
your cs2as plugins.

I may try to split ...build plugins into
    ...build containing *.mwe2 and *.xtend with Xtext nature
    ...resources containing *.ecore, *.uml without Xtext nature
so that no UML2 plugins appear on the ....build classpath.

The general guide seems to be, if there is an Xtext nature, then try as 
hard as possible to avoid models in the plugin or on the classpath. 
There are many different legacy UML *.ecore for the Xtext indexer to get 
its teeth into. Xtext-building org.eclipse.ocl.examples.build can take 
90 seconds!

    Regards

        Ed Willink