An interesting Evolutionary Design talk

I'm finally getting up to date with a non-trivial backlog of pending talks to watch, and today I watched one that resonated so much with me that I wanted to a) express how interesting it is and b) keep some notes about it in the blog, because it is so nicely explained.

If you like concepts like Test-Driven Development, the old Extreme Programming, or simply like to do true lean development and real iterative software building, I'm confident you will enjoy it. But I encourage everybody to watch it, even if you don't fully share the principles ¹.

The talk is Evolutionary Design Animated, by James Shore, presented at YOW! 2019. Consists of two parts, each around 25 minutes: Part I, Part II

Notes:

Evolutionary design:

1. Simple Design
2. Continuous Design
3. Reflective Design

All of them enabled by fast & reliable automated tests

Simple Design

• Start with a walking skeleton
• Do the simplest thing that could possibly work
• You Aren't Gonna Need It
• Simple, not sloppy

Rules for simple design:

"When, not if, I need to change this decision in the future, how hard will it be?"

• Every concept once
• ...And only once (don't repeat yourself)
• Design intent clear and obvious
• Concrete, not speculative
• Cohesive: code that changes together, stays together
• Decoupled: if it's out of sight, it's safely out of mind
• Isolated: if it's widely used, it's abstracted by an interface

Continuous Design

• Constantly review and improve the design
• Merciless refactoring
• Collective ownership
• Pairing and/or mobbing
• Continuous Integration
• Camp site rule: Don't make it perfect; just make it better

Reflective Design

• Review the code you're about to work on
• Identify flaws ("code smells", difficulty understanding)
• Reverse engineer design of code, if necessary
• Imagine how to improve the design of the code
• Incrementally refactor the code to reach desired design