Testing the type of a generic in delphi

Question

I want some way to write a function in delphi like the following

procedure Foo<T>;
begin
    if T = String then
    begin
        //Do something
    end;

    if T = Double then
    begin
        //Do something else
    end;
end;

ie: I want to be able to do different things based on a generic type

I've tried using TypeInfo in System but this seems to be suited to objects rather than generic types.

I'm not even sure this is possible in pascal

Answer 1

TypeInfo should work:

type
  TTest = class
    class procedure Foo<T>;
  end;

class procedure TTest.Foo<T>;
begin
  if TypeInfo(T) = TypeInfo(string) then
    Writeln('string')
  else if TypeInfo(T) = TypeInfo(Double) then
    Writeln('Double')
  else
    Writeln(PTypeInfo(TypeInfo(T))^.Name);
end;

procedure Main;
begin
  TTest.Foo<string>;
  TTest.Foo<Double>;
  TTest.Foo<Single>;
end;