Examples/test-suite/csharp/virtual_poly_runme.cs

using System;
using virtual_polyNamespace;

public class runme {
    static void Main() {

        NDouble d = new NDouble(3.5);
        NInt i = new NInt(2);

        //
        // These two natural 'copy' forms fail because no covariant (polymorphic) return types 
        // are supported in C#. 
        //
        // NDouble dc = d.copy();
        // NInt ic = i.copy();

        //
        // Unlike C++, we have to downcast instead.
        //
        NDouble dc = (NDouble)d.copy();
        NInt ic = (NInt)i.copy();

        NDouble ddc = NDouble.narrow(dc);
        NInt dic = NInt.narrow(ic);
        dc = ddc; ic = dic; // warning suppression

        virtual_poly.incr(ic);
        if ( (i.get() + 1) != ic.get() )
            throw new Exception("incr test failed");

        //
        // Checking a pure user downcast
        //
        NNumber n1 = d.copy();
        NNumber n2 = d.nnumber();
        NDouble dn1 = NDouble.narrow(n1);
        NDouble dn2 = NDouble.narrow(n2);

        if ( (dn1.get()) != dn2.get() )
          throw new Exception("copy/narrow test failed");

        //
        // Checking the ref polymorphic case
        //
        NNumber nr = d.ref_this();
        NDouble dr1 = NDouble.narrow(nr);
        NDouble dr2 = (NDouble)d.ref_this();
        if ( dr1.get() != dr2.get() )
          throw new Exception("copy/narrow test failed");
  }
}