[nradov]

Well that is one approach and it sometimes works. But usually it fails or least forces excessive rework because much of what you thought you knew at the beginning of the project later turns out to be incorrect. Another more agile approach is to avoid big up front design. Treat design as an emergent property and keep the internal OO design clean through constant refactoring.

https://en.wikipedia.org/wiki/Big_Design_Up_Front#Arguments_...