type TClass = class
protected f: integer;
internal
procedure Test(a : integer); abstract;
end;

TClass2 = class(TClass)
procedure Test(a : integer); override;
begin
end;
end;

TClass3 = class(TClass)
procedure Test2(k : real); abstract;
end;

TClass4 = class(TClass3)
constructor;
begin
  f := 4;
end;
procedure Test(a : integer); override;
begin
  assert(f = 4);
end;
procedure Test2(k : real); override;
begin
  assert(f = 4);
end;
end;

TClass5 = class(TClass2)
procedure Test3; abstract;
end;

TClass6 = class(TClass5)
constructor;
begin
  f := 6;
end;
procedure Test3; override;
begin
  assert(f = 6);
end;
end;

TClass7 = abstract class
a: integer;
procedure Test; virtual;
begin
a := 5;
end;
end;

TClass8 = class(TClass7)
procedure Test; override;
begin
a := 3;
end;
end;

var t : TClass;
    t2 : TClass3;
    t3 : TClass5;
    
begin
t := new TClass2;
t.Test(2);
t2 := new TClass4;
t2.Test2(2.3);
t3 := new TClass6;
t3.Test3;
var t4 := new TClass8;
t4.Test;
assert(t4.a=3);
end.