Continuous Design

https://www.martinfowler.com/ieeeSoftware/continuousDesign.pdf

T

he

rising popularity of refactoring, tools

such as JUnit, and agile methodologies

such as Extreme Programming (XP) has

brought a new style of design into view.

Continuous design

is the process of us-

ing refactoring to continuously improve

a program’s design. Initially a skeptic, I’ve been

experimenting with continuous design for four

years, and it’s changed the way I program

Design Goals in Continuous Design

Continuous design makes change easy by focusing on these design goals:

■

DRY (Don’t Repeat Yourself):

There’s little duplication.

■

Explicit:

Code clearly states its purpose, usually without needing comments.

■

Simple:

Specific approaches are preferred over generic ones. Design pat-

terns support features, not extensibility.

■

Cohesive:

Related code and concepts are grouped together.

■

Decoupled:

Unrelated code and concepts can be changed independently.

■

Isolated:

Third-party code is isolated behind a single interface.

■

Present-day:

The design doesn’t try to predict future features.

■

No hooks:

Interfaces, factory methods, events, and other extensibility “hooks”

are left out unless they meet a current need

Cohesive

内聚 -- 相关的代码和逻辑，放在一起。不要离散存放。

Isolated & Decoupled

去耦合 -- 将无关和不必要的粘连，切除掉。目标为更加内聚。

隔离 -- 将不同内聚的模块，切分清楚，将模块之间的接口描述清楚。