Conditional behaviour based on concrete type for generic class

Question

Since my question from yesterday was perhaps not completely clear and I did not get the answer I wanted, I will try to formulate it in a more general way:

Is there a way to implement special behaviour based on the actual type of an instantiated generic type either using explict conditional statements or using some kind of specialization? Pseudocode:

TGenericType <T> = class
  function Func : Integer;
end;
...
function TGenericType <T>.Func : Integer;
begin
  if (T = String) then Exit (0);
  if (T is class) then Exit (1);
end;
...
function TGenericType <T : class>.Func : Integer;
begin
Result := 1;
end;
function TGenericType <String>.Func : Integer;
begin
Result := 0;
end;

Answer 1

You can fall back to RTTI, by using TypeInfo(T) = TypeInfo(string). To test to see if something is a class, you could use something like PTypeInfo(TypeInfo(T))^.Kind = tkClass.

The PTypeInfo type and tkClass enumeration member are defined in the TypInfo unit.