Good Design is Easier to Change than Bad Design
From Pragmatic Programmers Book -> The Essence of Good Design:
Good Design Is Easier to Change Than Bad Design.
A thing is well designed if it adapts to the people who use it. For code, that means it must adapt by changing. So we believe in the ETC principle: Easier to Change. ETC. That’s it.
As far as we can tell, every design principle out there is a special case of ETC.
Why is decoupling good? Because by isolating concerns we make each easier to change. ETC.
Why is the single responsibility principle useful? Because a change in requirements is mirrored by a change in just one module. ETC.
Why is naming important? Because good names make code easier to read, and you have to read it to change it. ETC!