In C++, use the std::less and std::greater functors. Both of these methods inherit std::binary_function, so your generic function should accept instances of this type.
In .NET, the equivalent to std::binary_function is Func<T, U, R>. There are no equivalents to std::less and std::greater, but it is fairly trivial to create them. See the following example.
static class Functor
{
static Func<T, T, bool> Greater<T>()
where T : IComparable<T>
{
return delegate(T lhs, T rhs) { return lhs.CompareTo(rhs) > 0; };
}
static Func<T, T, bool> Less<T>()
where T : IComparable<T>
{
return delegate(T lhs, T rhs) { return lhs.CompareTo(rhs) < 0; };
}
}
Note, the above code uses the Func<> class from .NET 3.5. If this is not acceptable, consider defining you own delegate.
C++ invocation example:
void DoWork(const std::binary_function<int, int, bool>& myOperator,
int arg1, int arg2)
{
if (myOperator(arg1, arg2)) { /* perform rest of work */ }
}
void main()
{
DoWork(std::less<int>(), 100, 200);
DoWork(std::greater<int>(), 100, 200);
}
C# invocation example:
void DoWork(Func<int, int, bool> myOperator, int arg1, int arg2)
{
if (myOperator(arg1, arg2)) { /* perform rest of work */ }
}
void main()
{
DoWork(Functor.Less<int>(), 100, 200);
DoWork(Functor.Greater<int>(), 100, 200);
}
EDIT: I corrected the example of the functor class as applying < or > operators to a generic type doesn't work (in the same manner as it does with C++ templates).
