Delphi Language Guide Delphi for Microsoft Win32 Delphi for the Microsoft. Net framework

Overriding Versus Hiding
If a method declaration specifies the same method identifier and parameter signature as an inherited method, but
doesn't include override, the new declaration merely hides the inherited one without overriding it. Both methods exist
in the descendant class, where the method name is statically bound. For example,
type 
   T1 = class(TObject) 
      procedure Act; virtual; 
   end; 
   T2 = class(T1) 
      procedure Act;   // Act is redeclared, but not overridden 
   end; 
143

---

var
   SomeObject: T1; 
begin 
   SomeObject := T2.Create; 
   SomeObject.Act;    // calls T1.Act 
end;
Reintroduce
The reintroduce directive suppresses compiler warnings about hiding previously declared virtual methods. For
example,
procedure DoSomething; reintroduce;   // the ancestor class also has a DoSomething method
Use reintroduce when you want to hide an inherited virtual method with a new one.