In c# what does 'where T : class' mean?

Question

In C# what does where T : class mean?

Ie.

public IList DoThis() where T : class

Answer 1

where T: class literally means that T has to be a class. It can be any reference type. Now whenever any code calls your DoThis() method it must provide a class to replace T. For example if I were to call your DoThis() method then I will have to call it like following:

DoThis();

If your metthod is like like the following:

public IList DoThis() where T : class
{
   T variablename = new T();

   // other uses of T as a type

}

Then where ever T appears in your method, it will be replaced by MyClass. So the final method that the compiler calls , will look like the following:

public IList DoThis() 
{
   MyClass variablename= new MyClass();

  //other uses of MyClass as a type

  // all occurences of T will similarly be replace by MyClass
 }