파란크리스마스

type
  IDatabase = interface
    function GetDatabaseName() : String;
  end;

  TDatabase = class(TInterfacedObject, IDatabase)
  private
    FDtabaseName : String;
  public
    procedure SetDatabaseName(ADatabaseName : String);
    function GetDatabaseName() : String;
  end;

{ TDatabase }

procedure TDatabase.SetDatabaseName(ADatabaseName : String);
begin
  Self.FDtabaseName := ADatabaseName;
end;

function TDatabase.GetDatabaseName() : String;
begin
  Result := Self.FDtabaseName;
end;

{ TForm1 }

procedure TForm1.Button1Click(Sender: TObject);
var
  DatabaseList : TInterfaceList;
  ADatabase : TDatabase;
  InterfaceDatabase : IDatabase;
  i : integer;
begin
  DatabaseList := TInterfaceList.Create;

  ADatabase := TDatabase.Create;
  ADatabase.SetDatabaseName('Oracle');
  InterfaceDatabase := ADatabase;
  DatabaseList.Add(InterfaceDatabase);

  ADatabase := TDatabase.Create;
  ADatabase.SetDatabaseName('MsSQL');
  InterfaceDatabase := ADatabase;
  DatabaseList.Add(InterfaceDatabase);

  for i :=0 to DatabaseList.Count-1 do begin
    Memo1.Lines.Add(IDatabase(DatabaseList[i]).GetDatabaseName());
  end;
end;