Groovy metaprogramming with Java

Question

Say I have a large collection of Java static methods in a class of only static methods. All of them apply to some type of collection class. How can I scan this class, and using Groovy add each of them to the respective metaclasses?

So a sample might look something like this:

public class CollectionUtilities {    
    public static <T> T duplicates(Collection<T> coll) {
       return // some code to isolate the duplicates
    }
}

I'd want that to end up so I could call [1, 2, 2].duplicates() => [2]

Collection.metaClass.duplicates = { -> // replace coll usages with delegate }

Has anyone done anything like this?

Any idea of a good way to go about it?

Northover · Accepted Answer · 2011-02-16 03:21:32Z

1

You're on the right track with categories. A category can be employed locally as you demonstrated with your answer, or globally via mixin.

To add every method of your CollectionUtilities class to Collections at runtime, you can simply do the following:

Collection.mixin CollectionUtilities

answered Feb 16, 2011 at 3:21

Northover

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Comments

Alex Baranosky · Accepted Answer · 2011-02-16 02:21:19Z

0

I've found I can use the 'use' keyword to magically pull in a class like so:

use(src.CollectionUtilities) { 
   [1, 2, 3, 3].duplicates() 
} 
=> [3]

This is more of a brute force technique, and the code using the methods has to be contained within the clojure, I wonder still if there is a more precise way to do this......

answered Feb 16, 2011 at 2:21

Alex Baranosky

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