简约之美-软件设计之道-附录-笔记

《简约之美-软件设计之道-附录-笔记》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、简约之美-软件设计之道-附录-笔记APPENDIXA附录ＡTheLawsofSoftwareDesign软件设计的法则Thisappendixsummarizesalloftheactuallawsdiscussedinthisbook:本附录总结了书中讨论的所有可行的法则：1.Thepurposeofsoftwareistohelppeople.1.软件的目的是帮助他人.2.TheEquationofSoftwareDesign:D=(Vn+Vf)/(Ei+Em)　where:DStandsforthedesirabilityofthechange.VnStandsf

2、orvaluenow.VfStandsforfuturevalue.EiStandsfortheeffortofimplementation.EmStandsfortheeffortofmaintenance.Thisistheprimarylawofsoftwaredesign.Astimegoeson,thisequationreducesto:D=Vf/EmWhichdemonstratesthatitismoreimportanttoreducetheeffortofmaintenancethanitistoreducetheeffortofimplementa

3、tion.2.软件设计的方程式是：D=(Vn+Vf)/(Ei+Em)其中：D表示变化的合意程度(可行性).Vn表示当前价值.Vf表示未来价值.Ei表示开发成本.Em表示维护成本.这是软件设计的主要法则．随着时间的推移，这个方程式简化为：D=Vf/Em也就是说，相比降低实现成本，降低维护成本更重要．3.TheLawofChange:Thelongeryourprogramexists,themoreprobableitisthatanypieceofitwillhavetochange.3.变化定律：程序存在的时间越久，它的某个部分需要变化的可能性越大．4.TheLawo

4、fDefectProbability:Thechanceofintroducingadefectintoyourprogramisproportionaltothesizeofthechangesyoumaketoit.4.缺陷定律：在程序中新增缺陷的可能性与代码修改量成正比.5.TheLawofSimplicity:Theeaseofmaintenanceofanypieceofsoftwareisproportionaltothesimplicityofitsindividualpieces.5.简洁定律：软件任何一部分的维护难度，反比于该部分的简洁程度．6.The

5、LawofTesting:Thedegreetowhichyouknowhowyoursoftwarebehavesisthedegreetowhichyouhaveaccuratelytestedit.6.测试定律：你对软件行为的了解程度，等于你真正测试它的程度．That’sit.Manymorefactsandideaswerediscussedinthisbook,butthesesixitemsarethelawsofsoftwaredesign.Notethatofallofthese,themostimportanttobearinmindarethepur

6、poseofsoftware,thereducedformoftheEquationofSoftwareDesign,andtheLawofSimplicity.就是这么多．本书讨论了很多的事实和想法，但这６条是软件设计的法则．请注意，其中最重要的是牢记软件的目的，软件设计方程式的简化形式及简洁定律．Ifyouwantedtosumupthemostimportantfactstokeepinmindaboutsoftwaredesignintwosimplesentences,theywouldbe:.Itismoreimportanttoreducetheeffor

7、tofmaintenancethanitistoreducetheeffortofimplementation..Theeffortofmaintenanceisproportionaltothecomplexityofthesystem.Armedwithonlythosetwostatementsandanunderstandingofthepurposeofsoftware,youcouldverypossiblyre-evolvetheentirescienceofsoftwaredesign,providedthatyouals