Beck: Thought on Design Cost

"Design isn't free. ... When you put more design in today, you increase the overhead of the system. There is more to test, more to understand, more to explain. So everyday ... you pay a little design tax."
- Kent Beck's Extreme Programming Explained.

With more experience this is becoming truer and truer. As the design gets more general and seems to be preparing for potential future needs then there is more to test, understand, and explain. And yes it is that simple. That is not even counting the cost of the thought and white board time ( meaning less coding time ) going into the extra design.

Is it often worth the cost?

I am beginning to think not necessarily. Maybe the YAGNI question needs to be applied more thoughtfully to design and design decisions.

Another Reason To Like Kent Beck

Kent, regarding your comment that "all methodologies are based on fear". Would I be way off if I were to guess your fear was the Change Cost Curve? -- Ben Aveling

No, my fears are more about not spending enough time with my kids, growing away from my wife, and dying young of heart trouble like my grandfather. The Change Cost Curve I know how to handle.

---

from c2/KentBeck

"I Can Sleep When The Wind Blows"

The following story, from a Kent Beck article, illustrates one reason we have enjoyed learning and doing XP.

---

Once, a farmer interviewed a young man for a job as a farm hand. One thing the young man said particularly puzzled the farmer, “I can sleep when the wind blows.” The farmer didn’t know what this meant, but the young man seemed competent and knowledgeable and so he was hired.

A few months later the farmer was awakened in the middle of the night by a thunderous wind storm. Panicked, he raced to the cot where he found the farm hand fast asleep. Shaking him roughly awake, he demanded, “We have to bring in the animals!”

“They are already in.”

“We need to fasten the windows.”

“They are already fastened.”

“We need to tarp the hay.”

“It’s done.”

After going down his list of worries and being reassured that they were already taken care of, the farmer finally realized the meaning of the young man’s puzzling statement. By taking care to finish every job and leave the farm safe every night, the farm hand could sleep when the wind blew.

The farmer went back to bed and told his wife what he had just learned. She just smiled knowingly and the two of them went back to sleep, lulled by the music of the storm.

---

The rest of the article is here: Accountability In Software Development