《GOF设计模式》—生成器(Builder)—Delphi源码示例：ClassBuilder

示例：ClassBuilder

实现：

ClassBuilder是一个生成器，Class使用它为自己创建子类。在这个例子中，一个Class既是Director也是Product。

代码：

 

 

unit uClassBuilder;

 

interface

 

uses

    SysUtils;

 

type

    TClassBuilder = class;

 

    TClass = class

    public

        procedure Construct(Builder: TClassBuilder);

    end;

 

    TClassBuilder = class

    public

        procedure BuildClass(AClass:TClass); virtual;

    end;

 

    TConcreteBuilder = class(TClassBuilder)

    private

        FClassInfo: string;

    public

        constructor Create;

        //---

        procedure BuildClass(AClass:TClass); override;

        function GetResult: string;

    end;

 

implementation

 

procedure TClassBuilder.BuildClass;

begin

 

end;

 

constructor TConcreteBuilder.Create;

begin

    FClassInfo := '';

end;

 

procedure TConcreteBuilder.BuildClass(AClass:TClass);

begin

    FClassInfo := format('%0:s1 = class(%0:s) end;',[AClass.ClassName]);

end;

 

function TConcreteBuilder.GetResult: string;

begin

    Result := FClassInfo;

end;

 

procedure TClass.Construct(Builder: TClassBuilder);

begin

    Builder.BuildClass(self);

end;

 

end.

 

procedure TForm1.Button1Click(Sender: TObject);

var

    AClass: TClass;

    Builder: TConcreteBuilder;

begin

    AClass := TClass.Create;

    Builder := TConcreteBuilder.Create;

    //--

    AClass.Construct(Builder);

    showmessage(Builder.GetResult);

    //---

    Builder.Free;

    AClass.Free;

end;