unit Factory;

interface
uses Windows, Messages, SysUtils, Controls, Product;

type
  IFactoryInterface = interface
    function factory(): IProductInterface;
  end;

  TFactory1 = class(TControl, IFactoryInterface)
  public
    function factory(): IProductInterface;
  end;

  TFactory2 = class(TControl, IFactoryInterface)
  public
    function factory(): IProductInterface;
  end;

implementation

function TFactory1.factory(): IProductInterface;
var
  AProduct: TProduct1;
begin
  AProduct := TProduct1.Create(nil);
  Result := AProduct.CreateProduct();
end;

function TFactory2.factory(): IProductInterface;
var
  AProduct: TProduct2;
begin
  AProduct := TProduct2.Create(nil);
  Result := AProduct.CreateProduct();
end;

end.

unit Product;

interface
uses Windows, Messages, SysUtils, Controls, Dialogs;

type
  IProductInterface = interface
    function CreateProduct(): IProductInterface;
  end;

  TProduct1 = class(TControl, IProductInterface)
  public
    function CreateProduct(): IProductInterface;
  end;
  TProduct2 = class(TControl, IProductInterface)
  public
    function CreateProduct(): IProductInterface;
  end;

implementation

function TProduct1.CreateProduct(): IProductInterface;
begin
  Result := Self;
  showmessage('Product1 Created');
end;

function TProduct2.CreateProduct(): IProductInterface;
begin
  Result := Self;
  showmessage('Product2 Created');
end;

end.

//测试

procedure TForm1.Button1Click(Sender: TObject);
var
  AFactory: TFactory1;
begin
  AFactory := TFactory1.Create(Self);
  AFactory.factory;
  FreeAndNil(AFactory);
end;

procedure TForm1.Button2Click(Sender: TObject);
var
  AFactory: TFactory2;
begin
  AFactory := TFactory2.Create(Self);
  AFactory.factory;
  FreeAndNil(AFactory);
end;