Chapter 11. Reflection and code generation

In this chapter, we turn our attention to some of Go’s most interesting features. First, we present Go’s reflection system. Reflection, in software development, refers to a program’s ability to examine its own structure. Although Go’s reflection subsystem isn’t as versatile as Java’s, it’s still powerful. One feature that has enjoyed novel use is the annotation of structs. You’ll see in this chapter how to write custom tags for struct fields. As useful as Go’s reflection system is, though, sometimes it’s cleaner to avoid complex and expensive runtime reflection, and instead write code that writes code. Code generation can accomplish some of the things that are typically done in other languages with generics. That practice, called metaprogramming, is the last thing you’ll look at in this chapter.

11.1. Three features of reflection

Software developers use reflection to examine objects during runtime. In a strongly typed language like Go, you may want to find out whether a particular object satisfies an interface. Or discover what its underlying kind is. Or walk over its fields and modify the data.

11.2. Structs, tags, and annotations

11.3. Generating Go code with Go code

11.4. Summary