c# generic self-referencing declarations

Question

I\'ve been reading Albaharis\' \"C# 5.0 in A Nutshell\" and I\'ve encountered this in Generics section and it is said to be legal:

class Bar where T         


        

Answer 1

It is also helpful when you have a series of classes to write and you realize that 80% (pick a number) of the code is essentially the same except it varies by TYPE.

Writing a generic allows you to capture all that repetitive code in a base class and reuse it.

The specific pattern above is important/necessary because you want the T to be the class you are trying to write.

Imagine a framework where the crud object is based on crudBase and everything inherits from that. Imagine further that you have a base class that helps you query those objects (queryBase) and there will be a 1:1 with crudBase and queryBase classes.

Making queryBase a generic is simple because its fairly obvious how you would declare it

public abstract class queryBase where T : crudBase
{
 public list FindMatches(string SearchCriteria){}

  }

Without a generic, this would have to be in each concrete class because the return type changes. Generics are awesome.

what is a little less obvious is how to accomplish that same level of GENERIC nirvana with crudBase. Assume you have 70% of the boiler plate CRUD code already in a subclass, but there is another 10% where the logic needs to reference the type.
(pick a number, the % numbers are not important)

The GENERIC solution is less obvious here. In the first case you GENERIC class is referencing a different class with T. In this case, you want to reference the same class with T.

using the pattern described above you can in fact achieve this :

public class crudBaseGeneric where T : crudBaseGeneric
{
     public  CopyMe(){}
  }

Here you will redefine your base class as a generic and you will be able to capture that last 10%.

Again, without generics, I have to copy paste my CopyMe() function in each concrete class.