SOLID
A small acronym, that defines what we aim for in all out code.
This is almost a natural result of persuing unit testing (and mocking) to it's conclusion.
I try to follow these principals for each and every class and allow these principles to guide and refactoring or code review sessions.
Where I do have to violate these pinciples I try to limit the number of places where this happens within any single piece of sofware
and make sure that the offending code is as decoupled and isolated as possible.
Straight from Wikipedia...
Single responsibility principle
a class should have only a single responsibility (i.e. changes to only one part of the software's specification should be able to affect the specification of the class).
Open/closed principle
software entities … should be open for extension, but closed for modification.
Liskov substitution principle
objects in a program should be replaceable with instances of their subtypes without altering the correctness of that program.
Interface segregation principle
many client-specific interfaces are better than one general-purpose interface.
Dependency inversion principle
one should "depend upon abstractions, [not] concretions.
