• <ins id="pjuwb"></ins>
    <blockquote id="pjuwb"><pre id="pjuwb"></pre></blockquote>
    <noscript id="pjuwb"></noscript>
          <sup id="pjuwb"><pre id="pjuwb"></pre></sup>
            <dd id="pjuwb"></dd>
            <abbr id="pjuwb"></abbr>

            linux&c++ R&D

            programing is a pleasure!

            Understand decorator design pattern

                The Decorator Pattern is used for adding additional functionality to a particular object as opposed to a class of objects. It is easy to add functionality to an entire class of objects by subclassing an object, but it is impossible to extend a single object this way. With the Decorator Pattern, you can add functionality to a single object and leave others like it unmodified.
               A Decorator, also known as a Wrapper, is an object that has an interface identical to an object that it contains. Any calls that the decorator gets, it relays to the object that it contains, and adds its own functionality along the way, either before or after the call. This gives you a lot of flexibility, since you can change what the decorator does at runtime, as opposed to having the change be static and determined at compile time by subclassing. Since a Decorator complies with the interface that the object that it contains, the Decorator is indistinguishable from the object that it contains.  That is, a Decorator is a concrete instance of the abstract class, and thus is indistinguishable from any other concrete instance, including other decorators.   This can be used to great advantage, as you can recursively nest decorators without any other objects being able to tell the difference, allowing a near infinite amount of customization.



            An example:

            #include <iostream>
            class IntCompute{
            public:
                virtual 
            int Compute(int,int=0;
            }
            ;
            class IntComputeAdd:public IntCompute{
            public:
            int Compute(int a,int b){
                
            return a+b;
            }

            }
            ;
            class DecorateMinusAdd:public IntCompute{
            private:
                IntComputeAdd intadd;
            public:
                
            int Compute(int a,int b)
                
            {
                  
            return -(intadd.Compute(a,b));

                }

            }
            ;
            class DecorateSumSquare:public IntCompute{
            private:
                IntComputeAdd intadd;
            public:
                
            int Compute(int a,int b)
                
            {
                    
            int result=intadd.Compute(a,b);
                    
            return result*result;

                }

            }
            ;
            int main()
            {
             
            DecorateMinusAdd minadd;
            DecorateSumSquare sumsquare;
            std::cout
            <<minadd.Compute(10,20)<<std::endl;
            std::cout
            <<sumsquare.Compute(10,20)<<std::endl;
             
            return 0;
            }

            posted on 2007-05-11 21:38 丑石 閱讀(479) 評論(0)  編輯 收藏 引用 所屬分類: software engineering


            只有注冊用戶登錄后才能發(fā)表評論。
            網(wǎng)站導(dǎo)航: 博客園   IT新聞   BlogJava   博問   Chat2DB   管理


            My Links

            Blog Stats

            News

            常用鏈接

            留言簿(1)

            隨筆分類(13)

            隨筆檔案(17)

            文章檔案(1)

            相冊

            收藏夾(1)

            Friends' blog

            useful sites

            搜索

            積分與排名

            最新評論

            閱讀排行榜

            評論排行榜

            久久久无码精品亚洲日韩京东传媒 | 蜜臀av性久久久久蜜臀aⅴ| 欧美日韩精品久久久久| 无码国内精品久久综合88| 波多野结衣久久一区二区| 亚洲国产另类久久久精品小说| 国产精品久久久久9999| 亚洲精品乱码久久久久久蜜桃 | 91精品国产乱码久久久久久| 伊人丁香狠狠色综合久久| 中文字幕精品久久久久人妻| 色婷婷综合久久久久中文一区二区| 青青草原综合久久| 久久久久人妻精品一区二区三区 | 久久婷婷五月综合色奶水99啪| 国产精品青草久久久久福利99| 久久人人爽人人爽人人片AV东京热| 国产精品久久影院| 日本人妻丰满熟妇久久久久久 | 国产精品99久久久精品无码| 久久精品国产99国产电影网 | 国产精品美女久久久免费| 久久久久久免费视频| 99久久精品费精品国产一区二区| 国产精品欧美久久久久无广告| 成人资源影音先锋久久资源网| 久久人人爽人人爽人人爽 | 2021国产精品久久精品| 久久播电影网| 日韩精品久久久久久| 亚洲国产另类久久久精品小说| 久久99精品国产麻豆宅宅| 人妻丰满?V无码久久不卡| 久久艹国产| 亚洲国产综合久久天堂| 久久笫一福利免费导航| 久久九色综合九色99伊人| 久久久艹| 久久夜色精品国产亚洲| 99久久做夜夜爱天天做精品| 四虎亚洲国产成人久久精品|