S – I can find the thing I need to change.
O – My change will either be an extension or a replacement.
L – My replacement or extension needs to be a drop-in change.
I – Here’s what my replacement can do.
D – I have somewhere to put my replacement.
OOP the Easy Way
Object-Oriented Programming the Easy Way: a manifesto for reclaiming OOP from three decades of confusion and needless complexity.APPropriate Behaviour
APPosite Concerns
FSF