# Solid Book
这是本开源书，讲软件架构的
# Complexity
The goal of software design is to build products that server the needs of customer and can be cost-effectively changed by developers.
# Types of complexity
- essential complexity (业务本身引起的复杂性, 不可避免)
- Accidental complexity (可控的)
# Cause of accidental complexity
- High Coupling
- Low Cohesion
- More Developers (人多引起的inconsistent)
- Language And API capabilities (语言框架过于灵活引起的复杂性)
- Premature Optimization ( Premature optimization is the root of all evil )
# How to detect complexity
- Ripple 一个很小的需求改动可能要该很多地方
- Cognitive Load 认知负担
- Poor Discoverability (代码没有很好的组织 难以找到要修改的地方)
- Poor Understandability
- hard to understand how to use something
- hard to understand if we're using something the correct way. when tools provide too many options to do the same thing , it leaves us to question whether we made the correct decison or not
- hard to understand if what we did worked
# Mitigating Complexity
为了减少复杂性，作者推荐 Extreme Programming (敏捷的一种) ，并且指出如下实践:
- Pair programming
- TDD
- CI/CD
- Refactoring
- Coding Standard
- Code Ownership
- DDD