Groovy: Dynamically addings methods with a specific signature.

Question

So, I need to dynamically create (or inject) methods into an object that have a specific return type and method signature, because a Java tool we're using will be finding this methods via Reflection and checks for void type. Method names will be determined at runtime.

Using metaClass. = { ... } however adds a closure which doesn't show up as a regular method (even if it can be used as one) and also has a return type.

I can't modify the method finding code, and it it not Groovy-aware.

I can't use methodMissing() or invokeMethod() because the method needs to actually exist. If I could overload class.getMethods() I think it would be possible, but I can't figure out how.

Is there any way to do this in Groovy?

Answer 1

You could use AST Transformations to add the code at compile time, but it wont work on classes that you don't compile, so I'm guessing that probably wont work.

You could probably replace the object with a CGLIB based proxy. If you can be more specific about the code in question...

EDIT: A little more info. Groovy metaClass magic is not available in Java unless the Java code were to explicitly call groovyClass.invokeMethod("someMethod",args);. So there isn't a way to do what you're asking with MetaClasses. CGLIB maybe.