NOTE
Object-Oriented Design Principles
A practical view of SOLID and related principles for controlling coupling, responsibilities, and change.
This is a historical learning note and may contain outdated or incomplete understanding.
Design principles such as SOLID are heuristics for keeping responsibilities clear and dependencies manageable as software changes. They are not laws that require more interfaces or classes.
Apply them where they reduce the cost of change: isolate independent reasons to change, depend on stable abstractions where useful, keep contracts focused, preserve substitutability, and prefer composition when inheritance creates coupling. Simpler code wins when extra abstraction has no real payoff.