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This is the 4Th Arcticle: Builder PATTERN

Separates the construction of a complex object from its representation so that the same construction process can create different representations.  --Gof

 The builder pattern can separate the representation and construction easily , while you building a big-pang object , and some of the object itself  is

diversified and  could be build separately , considering this pattern.

Participants:

  • Builder.
    • specifies an abstract interface for creating parts of a Product object
  • ConcreteBuilder.
    • constructs and assembles parts of the product by implementing the Builder interface
    • defines and keeps track of the representation it creates
    • provides an interface for retrieving the product
  • Director.
    • constructs an object using the Builder interface
  • Product.
    • represents the complex object under construction. ConcreteBuilder builds the product's internal representation and defines the process by which it's assembled
    • includes classes that define the constituent parts, including interfaces for assembling the parts into the final result 


  •  The diagram goes here:


    Code is the most clearly lauguage for out programmers , so  I will use code to expree this pattern clearly as follows:

      1
      2/* this is the diversfied part*/
      3
      4//abstract
      5class House
      6{
      7
      8}
    ;
      9//abstract
     10class Door
     11{
     12
     13}
    ;
     14
     15//concrete, transformation
     16class FeDoor: public Door
     17{
     18
     19}
    ;
     20//concreate, transformation
     21class WoodDoor: public Door
     22{
     23
     24}
    ;
     25
     26//abstract
     27class Window
     28{
     29
     30}
    ;
     31//concreate , transformation
     32class FeWindow :public Window
     33{
     34
     35}
    ;
     36//concreate, transformation
     37class WoodWindow :public Window
     38{
     39
     40}
    ;
     41
     42/*this is the builder the stable part*/
     43class Builder
     44{
     45
     46protected:
     47    //build every part here
     48    virtual  void BuildeDoor();
     49    virtual  void BuildeWindow();
     50    virtual void  BuildFloor();
     51    //to get the result
     52public:
     53    virtual void GetHouse();
     54    
     55}

     56
     57class FeHouseBuilder :public Builder
     58{
     59public:
     60    GetHouse()
     61    {
     62        return /*window + door */
     63    }

     64protected:
     65    void BuildeDoor()
     66    {
     67       
     68        aDoor=new FeDoor();
     69    }

     70    void BuildWindow()
     71    {
     72        aRedWindow=new FeWindow();
     73    }

     74private:
     75    Window aWindow;
     76    Door aDoor;
     77
     78}

     79
     80class WoodHouseBuilder :public Builder
     81{
     82public:
     83    House GetHouse()
     84    {
     85        return /*window + door */
     86    }

     87protected:
     88    void BuildeDoor()
     89    {
     90       
     91        aDoor=new WoodDoor(); //can change 
     92    }

     93    void BuildWindow()
     94    {
     95        aRedWindow=new WoodWindow(); //can change too
     96    }

     97private:
     98    Window aWindow;
     99    Door aDoor;
    100
    101}

    102
    103class Director
    104{
    105public:
    106    //Create a house that has two doors and a window , this is the creator part , It's usually Stable too
    107    static House Construct(Builder builder)
    108    {
    109       builder.BuildeDoor();
    110       builder.BuildeDoor();
    111       builder.BuildeWindow();
    112
    113       return builder.GetHouse();
    114    }

    115
    116}
    ;
    117
    118//client
    119int main(int argc , char * argv[])
    120{
    121   //read the config file 
    122   //build a fe House with two doors and a window
    123    Director::Construct(new FeHouseBuilder());
    124   //builder a wood house with two doors and a window 
    125    Director::Construct(new WoodHouseBuilder());
    126
    127    /*two doors and a window is stable , and  the house 's architecture is stable too ,but the material*/
    128
    129}


     1-40  is the diversification , the house's architecture is stable , you create a mixed house easily if you like ,  simply add a class called mixedhouseBuidler and use the right part(like the FeDoor  and WoodDoor ) to create the mixed house ,and use the mixedHouseBuilder to builde you work.

    simple and practible!
    posted on 2007-06-02 17:34 常兴龙 阅读(992) 评论(4)  编辑 收藏 引用 所属分类: Design Patterns & Engeering

    评论

    # re: Implement "GOF's Builder pattern" Using C++(Series of Gof patterns using C++ 4th article) 2007-06-02 20:28 万星星
    用设计模式来设计一个真实的系统,把理想的东西和现实的世界结合起来,或许可以学到更多,成长更快,理解的更加深刻。
    一个系统用上4、5个模式应该就比较成功了。  回复  更多评论
      

    # re: Implement "GOF's Builder pattern" Using C++(Series of Gof patterns using C++ 4th article) 2007-06-03 14:12 常兴龙
    设计模式,相似的代码很可能是不同的模式,不同的代码很可能是相同的模式思想。万变不离其踪,这里只给了一种自我思考的例子。放入工程中别人很难看清楚是什么,因而不能发表其也许更好的见解。多谢评论!  回复  更多评论
      

    # re: Implement "GOF's Builder pattern" Using C++(Series of Gof patterns using C++ 4th article) 2007-06-04 13:58 picasa
    谁能翻一下  回复  更多评论
      

    # re: Implement "GOF's Builder pattern" Using C++(Series of Gof patterns using C++ 4th article) 2007-09-28 20:12 马承志
    主人的想法非常好,当然如果能在现实的项目中使用模式解决问题才是根本.不过通过C++完成所有的模式也是一种实践.可以加深我们的理解.非常支持你的做法,不过我现在觉得重构到模式可能更能解决实际问题.你的目标非常具体,是我的学习榜样.希望我们以后能够多交流  回复  更多评论
      


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