The Hidden Power of Humble Interfaces (GopherCon Singapore 2017)

Learn how to design your own interfaces in Go that are simple yet powerful – just like io.Reader and error. Discover the techniques for correctly identifying the places where interfaces will improve our code, and the specific steps to ensuring that our interfaces are as powerful as they can be.

Transcript

1. The Hidden Power of Humble Interfaces Aditya Mukerjee @ChimeraCoder GopherCon Singapore May 26, 2017
2. @chimeracoder
5. Why use interfaces? • Write less code • Write robust code • Write flexible code @chimeracoder
6. Interfaces: The Basics
7. @chimeracoder
8. io.* interfaces @chimeracoder
9. Composite interfaces @chimeracoder
10. Interface helper functions @chimeracoder
11. What makes the io interfaces powerful? • Abstracting a lot of common functionality • Lots of granularity • Plethora of helper functions @chimeracoder
12. What makes error powerful? • Abstracts no functionality • Provides no granularity • Provides (almost) no helper functions @chimeracoder
13. So what makes a powerful interface, anyway? @chimeracoder
14. Humility and Discipline • Keep interfaces humble • Writing interfaces forces you to define the minimum required contract for using your types • Keep interfaces disciplined • Writing interfaces allows the compiler to enforce this contract @chimeracoder
15. type Foo struct interface { } @chimeracoder
16. Why Gophers avoid interfaces • Afraid of writing an interface that is too complicated • Afraid of specifying the wrong methods @chimeracoder
17. How I Learned To Stop Worrying and Love the interface • Interfaces reveal the assumptions you’re already making • “If it’s there, you will use it” @chimeracoder
18. Every time you access a field or method, you’re making an assumption @chimeracoder
19. So how should I design these interfaces? @chimeracoder
20. Writing interfaces like io.* • Don’t write helper methods until you actually find you need them • The contracts provided by each should be minimal • Create composite interface types @chimeracoder
21. Writing interfaces like error • Ask interfaces how they behave @chimeracoder
22. What if structs could never be exported? @chimeracoder
23. Aditya Mukerjee @chimeracoder https://github.com/ChimeraCoder Thank you!