#17 Restricting Scope

Congratulations for putting this series of screencasts about Xtext.

I jumped straight on episode 17, since I am currently implementing scoping in a DSL, and I am a beginner with Xtext.

Some comments on the episode:

• Really liked it – extremely useful
• It would be nice to show the version of Xtext that you are using. I could see some differences between Xtext 2.4 documentation and episode 17.
• What version of Xtext / Xtend are you using? I am using Xtext SDK 2.4.2.v201306120542 ; any possibility of upgrading the tutorials to the latest version of Xtext? For example, xtend scoping is automatically generated (raher than java). The main problem I had was with the fact that Xtext 2.4 automatically generates Xtend code; no need to create Xtend source file copied from a Java source file.
• The documentation for Xtext version 2.4 is of limited help. Section 8.6.2 "Local scoping" does not use the def keyword nor the :: operator. Also the syntax for filtering presented in your video is very useful, and not at all obvious from the Xtext doc.
• An extended scoping tutorial would be welcome, explaining the declarative scoping in detail.

I'm happy you like XtextCasts!

Also thank you for the advice with the version information. I already put the versions of the used software at the bottom on the show notes of the episode 17. I will do it for all other episodes soon.

And here again:

• Eclipse version: 4.2 (Juno)
• Xtext version: 2.3

There shouldn't be so much differences between Xtext 2.3 and 2.4 considering episode 17. What problems do you have exactly?

Operators:

• The documentation uses def keyword. For example, see definition of the compile method def compile(Entity e) (page 28).
• The '::' operator is good, if you want to call a static method, see "Character::isUpperCase(..)" (page 32)

The extended scoping tutorial is planed, but the topic is pretty complicated and because of this very time consuming :-(

Awesome, really helpful!
Had to bring this together with an ImportedNamespaceAwareScopeProvider (INASP). Just learned that, by default, the AbstractDeclarativeScopeProvider (ADSP) delegates to INASP when it cannot find a scope itself.

So, when you have a specialization of INASP and one for ADSP, you are fine by just binding them like this in the RuntimeModule of your language:

@Override
public Class<? extends IScopeProvider> bindIScopeProvider() {
return YourADSP.class;
}

public Class<? extends ImportedNamespaceAwareLocalScopeProvider> bindImportScopeProvider() {
return YourINASP.class;
}

Will have a look at the other casts.

this is an example to limit scope to the active DSL file only
(based on the standard XTEXT project)
with a lot of help from the forum:
"reducing cross reference to current DSL file" http://www.eclipse.org/forums/index.php/t/635607/

Greetings from Frankfurt/Germany
Uli

P.S. @Boris: your screencasts are a great support for XTEXT newbies like me

// ##### our new ScopeProvider (NullGlobalScopeProvider.java)
package org.xtext.example.mydsl;

import org.eclipse.emf.ecore.EReference;
import org.eclipse.emf.ecore.resource.Resource;
import org.eclipse.xtext.resource.IEObjectDescription;
import org.eclipse.xtext.scoping.IGlobalScopeProvider;
import org.eclipse.xtext.scoping.IScope;
import com.google.common.base.Predicate;

public class NullGlobalScopeProvider implements IGlobalScopeProvider {

  @Override
  public IScope getScope(Resource context, EReference reference,
                Predicate<IEObjectDescription> filter) {
    return IScope.NULLSCOPE;
  }
}

// ##### binding it in MyDslRuntimeModule.java
package org.xtext.example.mydsl;

import org.eclipse.xtext.scoping.IGlobalScopeProvider;

public class MyDslRuntimeModule 
  extends org.xtext.example.mydsl.AbstractMyDslRuntimeModule {
  @Override
  public Class<? extends IGlobalScopeProvider> bindIGlobalScopeProvider() {
    return NullGlobalScopeProvider.class;
  }
}