Characteristics of a Good API

• • Easy to learn
• • Easy to use, even without documentation
• • Hard to misuse
• • Expose only what is required
• • Easy to read and maintain code that uses it
• • Sufficiently powerful to satisfy requirements
• • Easy to extend
• • Appropriate to audience

General Principles

• API Should Be As Small As Possible But No Smaller
• Implementation Should Not Impact API
• Minimize Accessibility of Everything
• Names Matter–API is a Little Language
• Documentation Matters
• Document Religiously
• Consider Performance Consequences of API Design Decisions
• Effects of API Design Decisions on Performance are Real and Permanent
• API Must Coexist Peacefully with Platform