Criteria for good design
Uncle Bob listed a few Design smells -- the odors of rotting software in his book Agile Software Development. Take the inverse of that and what do you get? Criteria for good design -- that's the approach that the author of the book PHP in Action took.
Here are the characteristics of good design.
- Flexibility - easy to change
- Robustness - hard to break
- Mobility - easy to disentagle into reusable components
- Fluidity - easy to do things right
- Simplicity
- Once and only once
- Transparency - easy to read and understand
Very good criteria, in my opinion.