Cannot override methods via metaclass that are part of an interface implementation

Todd Greenwood added a comment - 22/Oct/09 4:17 PM - edited Adding repro steps for java classes. //-------------------------------------------- // REPRO 2: Override a java class instance...should work, and does //-------------------------------------------- #JavaClass.java public class JavaClass { public Object doSomething( Object o) { throw new IllegalStateException( "This method should be overriden" ); } } #MyScript.groovy class Dog { String name; } JavaClass jc = new JavaClass(); jc.metaClass.doSomething = { Object o -> println o; return o; } def dog = new Dog().name= "fido" ; assert (jc.doSomething(dog).equals(dog)); //-------------------------------------------- // REPRO 3: Override a java class instance // based on an interface...this does not work //-------------------------------------------- #IWorker.java public interface IWorker { public Object doSomething( Object o); } #LazyWorker.java public class LazyWorker implements IWorker { @Override public Object doSomething( final Object o ) { throw new IllegalStateException( "should be overridden" ); } } #MyScript.groovy IWorker lw = new LazyWorker(); lw.metaClass.doSomething = { Object o -> println o; return o; } assert (lw.doSomething(dog).equals(dog)); ERROR: The metaClass override is ignored, and the IllegalStateException from the original impl is used.