Re: Porting C++ Template to Java Generic

Daniel Pitts <>
Mon, 19 May 2008 14:59:18 -0700
Aadain wrote:

On May 17, 12:19 pm, "Chronic Philharmonic" <>

Port the design, not the code.

This is exactly what I am attempting to do. I've porting the
functionality of the program, which itself is pretty efficient and
mostly language neutral. There were plenty of operations that took
advantage of C++ functionality, such as the original problem I
demonstrated in the original post. After doing some digging and some
thinking on my own, I'm beginning to think that the solution is create
a simple master class that implements basic math for all possible
types that the generic types will take (there are only a handful) and
requiring the generic class to extend that master class. Then instead
of the command

return t1.Evaluate() * t2.Evaluate();

It would look like

return t1.Evaluate().mult(t2.Evaluate());

Since Java doesn't support operator overloading, that does make sense.

Has anyone else done something similar with generics before?

You don't even *need* generics for this, you *can* use a simple
interface, although it could help.

interface Addible<R,T> {
    R add(T t);

class MyInt extends Addible<MyInt, MyInt> {
    private final int value;
    public MyInt(int value) {
      this.value = value;
    public MyInt add(MyInt other) {
      return new MyInt(value + other.value);

public class DoesSomeWork {
   public static <T extends Addible<T,T>> T sumOf(Collection<T> addable){
     Iterator<T> it = addible.iterator();
     if (!it.hasNext()) {
        return null;

     T current =;
     while (it.hasNext() {
        current = current.add(;
     return current;

MyInt total = DoesSomeWork.sumOf(myIntList);

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His body a blood-ruby radiant
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