SOLID — Interface Segregation Principle: Question bank

Before we begin, the words we lean on repeatedly:

ISP — Interface Segregation Principle: no client should be forced to depend on methods it does not use.
Client — any code that depends on an interface. This includes the caller AND the implementer. Both are dragged into whatever the interface declares.
Role interface — a small interface defined by what one kind of client needs, grouping only methods that are used together.
Fat interface — one interface bundling capabilities that different clients use separately.

The forced-dependency metric (symbols defined once, used throughout)

Several traps below refer to a small counting formula. We define it carefully here so no symbol appears unexplained.

Parent: ISP
SOLID — Single Responsibility Principle — the class-level cousin of these traps.
SOLID — Liskov Substitution Principle — the stub trap lives here too.
SOLID — Dependency Inversion Principle — role interfaces as clean abstractions.
Cohesion and Coupling — the metric behind "split by role."
Design Patterns — Adapter — taming fat third-party contracts.