Question

In the older (1.x.x) versions of Groovy you can add constructors using metaClass.constructor

Example.metaClass.constructor << { String arg0 -> new Example(arg0, "") }

Is there a way to register constructors using the new Groovy 2.0 extension modules?

This seems to work:

Define an extension class as normal for Groovy 2 and just add the constructors in a static initialiser

public class ExampleHelper {
    static {
        Example.metaClass.constructor << { String arg0 -> new Example(arg0, "") }
    }
}

Answer 1

Not that I know of…

You could add a static factory method to the Example class ie:

class ExampleExtensionStatic {
  public static Example newInstance( Example type, String arg0 ) {
    new Example( arg0, '' )
  }
}

Then (after adding a link to this class in the staticExtensionClasses field of the org.codehaus.groovy.runtime.ExtensionModule file), you could do:

Example.newInstance( 'arg0' )

This is something worth asking on the mailing list to see if constructors are worth adding to the Module Extension system.