IDispatch = interface(IUnknown)
['{00020400-0000-0000-C000-000000000046}']
function GetTypeInfoCount(out Count: Integer): HResult; stdcall; 
function GetTypeInfo(Index, LocaleID: Integer; out TypeInfo): HResult; stdcall; 
function GetIDsOfNames(const IID: TGUID; Names: Pointer; NameCount, LocaleID: Integer; DispIDs: Pointer): HResult; stdcall; 
function Invoke(DispID: Integer; const IID: TGUID; LocaleID: Integer; Flags: Word; var Params; VarResult, ExcepInfo, ArgErr: Pointer): HResult; stdcall; 
end;

type
IFoo = Interface
['{2137BF60-AA33-11D0-A9BF-9A4537A42701}'] 
function F1 : Integer; 
end;

type
IBar = Interface(IFoo)
['{2137BF61-AA33-11D0-A9BF-9A4537A42701}'] 
function F2 : Integer; 
end;

type
TFooBar = class(TInterfacedObject, IFoo, IBar) 
function F1 : Integer; 
function F2 : Integer; 
end;

function TFooBar.F1 : Interger;
begin
Result := 0; 
end;

function TFooBar.F2 : Interger;
begin
Result := 0; 
end;

type
IFoo = Interface 
['{2137BF60-AA33-11D0-A9BF-9A4537A42701}'] 
function F1 : Integer; 
end;

type
IBar = Interface
['{2137BF61-AA33-11D0-A9BF-9A4537A42701}'] 
function F1 : Integer; 
end;

TFooBar = class(TInterfacedObject, IFoo, IBar)
//为同名方法取别名
function IFoo.F1 = FooF1; 
function IBar.F1 = BarF1; 
//接口方法 
function FooF1 : Integer; 
function BarF1 : Integer; 
end;

function TFooBar.FooF1 : Interger;
begin
Result := 0; 
end;

function TFooBar.BarF1 : Interger;
begin
Result := 0; 
end;

type
TSomeClass = class(TInterfacedObject, IFoo)
//Stuff 
function GetFoo : TFoo; 
property Foo : TFoo read GetFoo implements GetFoo; 
//Stuff 
end;

var
I : ISomeInterface; 
begin

//I被初始化为nil
I := FunctionReturningAnInterface; //I的引用计数加1

I.SomeFunc;

//I的引用计数减1，如果为0，则自动释放。

end;

procedure Test(FB : TFooBar)
var
F : IFoo; 
begin

F :=FB; //合法，因为FB支持IFoo
.
. 
.

var
FB : TFooBar; 
F : IFoo; 
B : IBar; 
begin
FB := TFooBar.create;

F :=FB; //合法，因为FB支持IFoo
B := F as IBar; //把F转换为IBar