Go Documentation

Go Documentation

Resource Routing

• scripts/check-docs.sh - Run when checking exported functions, types, methods, constants, and packages for missing doc comments.
• scripts/check-docs-ast.go - Implementation helper invoked by check-docs.sh; patch this when changing documentation analysis behavior.
• assets/doc-template.go - Use when starting a documented package or exported API.
• references/CONVENTIONS.md - Read when documenting parameters, context behavior, concurrency safety, cleanup, errors, or named results.
• references/EXAMPLES.md - Read when adding runnable examples or package examples.
• references/FORMATTING.md - Read when formatting Godoc lists, paragraphs, links, and code blocks.

Doc Comments

Normative: All top-level exported names must have doc comments.

Basic Rules

1. Begin with the name of the object being described
2. An article ("a", "an", "the") may precede the name
3. Use full sentences (capitalized, punctuated)

// A Request represents a request to run a command.
type Request struct { ...

// Encode writes the JSON encoding of req to w.
func Encode(w io.Writer, req *Request) { ...

Unexported types/functions with unobvious behavior should also have doc comments.

Validation: After adding doc comments, run bash scripts/check-docs.sh to verify no exported symbols are missing documentation. Fix any gaps before proceeding.

Comment Sentences

Normative: Documentation comments must be complete sentences.

• Capitalize the first word, end with punctuation
• Exception: may begin with uncapitalized identifier if clear
• End-of-line comments for struct fields can be phrases

Comment Line Length

Advisory: Aim for ~80 columns, but no hard limit.

Break based on punctuation. Don't split long URLs.

Struct Documentation

Group fields with section comments. Mark optional fields with defaults:

type Options struct {
    // General setup:
    Name  string
    Group *FooGroup

    // Customization:
    LargeGroupThreshold int // optional; default: 10
}

Package Comments

Normative: Every package must have exactly one package comment.

// Package math provides basic constants and mathematical functions.
package math

• For main packages, use the binary name: // The seed_generator command ...
• For long package comments, use a doc.go file

What to Document

Advisory: Document non-obvious behavior, not obvious behavior.

Key principles:

• Context cancellation returning ctx.Err() is implied — don't restate it
• Read-only ops are assumed thread-safe; mutations assumed unsafe — don't restate
• Always document cleanup requirements (e.g., Call Stop to release resources)
• Use pointer in error type docs (*PathError) for correct errors.Is/errors.As
• Don't name results just to enable naked returns — clarity > brevity

Runnable Examples

Advisory: Provide runnable examples in test files (*_test.go).

func ExampleConfig_WriteTo() {
    cfg := &Config{Name: "example"}
    cfg.WriteTo(os.Stdout)
    // Output:
    // {"name": "example"}
}

Examples appear in Godoc attached to the documented element.

Quick Reference

Related Skills

• Naming conventions: See go-naming when choosing names for the identifiers your doc comments describe
• Testing examples: See go-testing when writing runnable Example test functions that appear in godoc
• Linting enforcement: See go-linting when using revive or other linters to enforce doc comment presence
• Style principles: See go-style-core when balancing documentation verbosity against clarity and concision