Useful principles of Obejct Oriented Design. These were introduced by Uncle Bob (Robert C. Martin).
| S | Singleton |
| T | Tight Coupling |
| U | Untestability |
| P | Premature Optimization |
| I | Indescriptive Naming |
| D | Duplication |
| S | Single Responsibility |
| O | Open-close |
| L | Liskov substitution |
| I | Interface segregation |
| D | Dependency inversion |
A class should have a single reason to change. - Separation of Concerns
The system should be open to extension and closed to modification.
- We want to avoid modifying code that already works.
- Extension can be done by inheritance.
Subtypes should be inmediatly substitutable by their base types.
- Methods designed to work on the Base class should keep working when a Derived instance is used.
- Named after Robert Liskov.
Avoid putting too much into a single interface. Don't force implementers to code too large interfaces.
- Partial implementers contain dummy methods and extra code.
- Partial implementers give a wrong API to the user.
- High-level modules should not depend on low-level modules. Both should depend on abstractions.
- Abstractions should not depend on details. Details should depend on abstractions.
Prefer depending on abstractions (abstract and interfaces) rather than specific classes. Avoid depending on the implementation details.