12-solid-design-principles.md

layout	title	date	comments	categories	language	references
post	SOLID Design Principles	2018-08-13 18:07	true	system design	en	https://www.amazon.com/Clean-Architecture-Craftsmans-Software-Structure/dp/0134494164

SOLID is an acronym of design principles that help software engineers write solid code within a project.

1. S - Single Responsibility Principle. A module should be responsible to one, and only one, actor. a module is just a cohesive set of functions and data structures.

2. O - Open/Closed Principle. A software artifact should be open for extension but closed for modification.

3. L - Liskov’s Substitution Principle. Simplify code with interface and implementation, generics, sub-classing, and duck-typing for inheritance.

4. I - Interface Segregation Principle. Segregate the monolithic interface into smaller ones to decouple modules.

5. D - Dependency Inversion Principle. The source code dependencies are inverted against the flow of control. most visible organizing principle in our architecture diagrams.

   1. Things should be stable concrete, Or stale abstract, not ==concrete and volatile.==
   2. So use ==abstract factory== to create volatile concrete objects (manage undesirable dependency.) 产生 interface 的 interface
   3. DIP violations cannot be entirely removed. Most systems will contain at least one such concrete component — this component is often called main.