Is there a technique to differentiate class behavior on generic types?

Question

I'd like to do something like the following, but because T is essentially just a System.Object this won't work. I know T can be constrained by an interface, but that isn't an option.

public class Vborr<T> where T : struct
  {

    public Vborr()
    {
    public T Next()
    {
      if ( typeof( T ) == typeof( Double ) )
      {
         // do something for doubles
      }
      if ( typeof( T ) == typeof( Float ) )
      {
         // do something different for floats..
      }
    }
  }

I frequently find C# generics lacking.

Thanks!

Paul

Answer 1

The whole point of generics is that you can do the same thing for any valid type.

If you're truly doing something specific for the types, then the method isn't generic anymore and should be overloaded for each specific type.

public class Vborr<T> where T : struct
{
    public virtual T Next() { // Generic Implementation }
}

public class VborrInt : Vborr<int>
{
    public override int Next() { // Specific to int }
}

public class VborrDouble : Vborr<double>
{
    public override double Next() { // Specific to double }
}

Answer 2

The approach I would take here would be that of a factory pattern and creating specialized instances of Vborr based off of the type. For example

public class Vborr<T> where T : struct {
  protected Vborr() { }
  abstract T Next();
}

public static class VborrFactory { 
  private sealed class VborrFloat : Vborr<float> {
    public VborrFloat() {}
    public override float Next() {
      ...
    }
  }
  private sealed class VborrDouble : Vborr<double> {
    public VborrDobule() {}
    public override double Next() {
      ...
    }
  }
  private sealed class VborrDefault<U> : Vborr<U> {
    public VborrDefault() {}
    public override U Next() {
      ...
    }
  }
  public static Vborr<T> Create<T>() {
    if (typeof(T) == typeof(double) ) { 
      return new VborrDouble();
    } else if ( typeof(T) == typeof(float) ) {
      return new VborrFloat();
    } else {
      return new VborrDefault<T>();
    }
  }
}