public abstract class BizEntity<IdentiferType> 
         where IdentiferType : struct, IComparable<IdentiferType>
{
  //...
  // По сути всё, что внешний мир должен о нём знать
  public IdentiferType EntityID {
    get {
    }
  }
  //...
}

public class BizEntityManager<IdentiferType> where IdentiferType : struct, IComparable<IdentiferType>
{
  //...

  E Load<E, IdentiferType>(IdentiferType ID) 
                 where E : BizEntity<IdentiferType>
                 where IdentiferType : struct, IComparable<IdentiferType>
  {
  }

  //...
}

using constraint IdentiferTypeC = struct, IComparable<IdentiferType>

public abstract class BizEntity<IdentiferType> where IdentiferType : IdentiferTypeC
{
  //...
  // По сути всё, что внешний мир должен о нём знать
  public IdentiferType EntityID {
    get {
    }
  }
  //...
}

Metaprogramming is the writing of programs that write or manipulate other programs (or themselves) as their data or that do part of the work that is otherwise done at runtime during compile time. This allows programmers to produce a larger amount of code and get more done in the same amount of time as they would take to write all the code manually.

In computer science, generics is a technique that allows one value to take different datatypes (so-called polymorphism) as long as certain contracts such as subtypes and signature are kept. The programming style emphasizing use of this technique is called generic programming.

Если вы все такие умные, чего же вы строем не ходите?

std::vector<int> v( 10 );
for (std::vector<int>::iterator i = v.begin(), e = v.end(); i != e; ++i)
   *i = e - i;

> ПК>std::vector<int> v( 10 );
> ПК>for (std::vector<int>::iterator i = v.begin(), e = v.end(); i != e; ++i)
> ПК>   *i = e - i;
> ПК>

Metaprogramming is the writing of programs that write or manipulate other programs (or themselves) as their data or that do part of the work that is otherwise done at runtime during compile time.

• writing of programs that write other programs (or themselves)
  
• writing of programs that manipulate other programs (or themselves) as their data
  
• writing of programs that do part of the work that is otherwise done at runtime during compile time