2.Software Myths 产身 粉道8 Case2cont)】 A week later the boss called the engineer into his office and asked, “Where are we?” “Everything's going wel,”said the youngster,“butI've run into a few small snags.I'll get them ironed out and be back on track soon." “How does the deadline look?”the boss asked “No problem,”said the engineer.“I'm close to 90 percent complete.” If you've been working in the software world for more than a few years,you can finish the story.It'll come as no surprise that the young engineer stayed 90 percent complete for the entire project duration and only finished(with the help of others)one month late
Slide 1.11 11/21 2. Software Myths
2.Software Myths Customer myths Myth:Project requirements continually change,but change can be easily accommodated because software is flexible. Reality:The impact of change is shown by the figure. 60-100 eBueyo Jo isoo 1.56x 1x 88 Definition Development After release
Slide 1.12 12/21 2. Software Myths
2.Software Myths Practitioner's myths Myth:Once we write the program and get it to work,our job is done. oo Cse3某公园有一游船码头，负责人希望开发一游船管理系统， 要求如下：当游客租船时，管理员输入S表示租船周期开始；当游客 还船时，管理员输入表示租船周期结束。一天结束时，要求系统打 印出粗船次数和平均租船时间。 新要求：输出一天中的最长 Realify:Someone once said that "the 租用时间。 sooner you begin 'writing code',the 新要求：将报告分上午和下 longer it'll take you to get done." 午输出。 Industry data indicate that between 60 新要求：当通信线路出问题 and 80 percent of all effort expended on 时，能从计算中刷除一切不 a program will be expended after it is 完整的租船信息。 delivered to the customer for the first time
Slide 1.13 13/21 2. Software Myths
2.Software Myths Practitioner Myths X写程序才算是真的干活，写文档不算 干活。 Vdocument:foundation guidance X软件工程只会给我们增加无数的文档， 降低进度。 Vsoftware:enhance quality speed
Slide 1.14 14/21 2. Software Myths Practitioner Myths ✘写程序才算是真的干活，写文档不算 干活。 ✔document: foundation & guidance ✘软件工程只会给我们增加无数的文档， 降低进度。 ✔software: enhance quality & speed
2.Software Myths ●Practitioner Myths 这里还有一个故事. 1980s,America,Internal Revenue Service(IRS),自动收税系统，耗资 $103 million,Inadequte?”,”cost twice ●1985，追加$90 nillion,不断修改. ●1996，情况并无改观，只产出了6000页 的文档。“a$4 billion fiasco(大失败) because of inadequate planning
Slide 1.15 15/21 2. Software Myths ⚫ Practitioner Myths 这里还有一个故事. ⚫1980s, America, Internal Revenue Service(IRS),自动收税系统，耗资 $103million, ”Inadequte”,”cost twice” ⚫1985，追加$90million，不断修改. ⚫1996，情况并无改观，只产出了6000页 的文档。“a $4 billion fiasco（大失败） because of inadequate planning