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POAdd Scala operators to final Java class
 

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    <p>I am using the jMonkeyEngine (Java Game Engine) in Scala, which works out pretty well so far, but now I am asking myself whether there is an elegant way of overloading operators for the <code>Vector3f</code> (and similar) classes. My first idea was to inherit from <code>Vector3f</code> and overload the operators, but <code>Vector3f</code> is final, so that is not an option. Next I thought maybe I could have a singleton/scala object with static methods that operate on <code>Vector3f</code>, like below, but that does not work either:</p> <pre><code>object VectorMath { def *(factor: Float, vector: Vector3f) = vector.mult(factor) } //and then somewhere import VectorMath._ var v = new Vector3f(1,2,3); var u = 1.2f * v; //this does not work, because Float does not have * overloaded for Vector3f var u = VectorMath.*(1.2f, v); //this does work, but defeats the purpose </code></pre> <p>So all I can think of now is to wrap the Vector3f in a new Scala class and delegate the operator calls to the appropriate Java methods. This has, however, three downsides:</p> <ol> <li>I will have to do to a lot of back and forth conversions (a <code>toVector3f</code> and a <code>fromVector3f</code> method or something like that).</li> <li>This problem becomes even worse when I have arrays of Vector3f/ScalaVectors. Since the classes are not related (except by composition), I would have to manually cast every element of the array every time I call a method in jME. </li> <li>Even then I know of no way to overload an operator for my new ScalaVector class in such a way that I could have the factor in front, i.e. <code>1.2f * v</code>.</li> </ol> <p>My question: Can someone think of a way to make this more natural/elegant? How do you tackle similar problems? Or is there maybe a Scala syntax that I don know of to do these kinds of things? In C++ I would make a global operator that takes float and Vector3f as arguments and possibly friend it. Whats the Scala way to do this, or is that simply not possible?</p>
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