# go-functions

Organizes Go file structure, formats long function signatures, and enforces Printf naming conventions. Helpful when writing or refactoring Go methods.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 1000 installs · ★ 181
- Author: cxuu
- License: Apache-2.0 · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/cxuu/golang-skills/tree/HEAD/skills/go-functions/SKILL.md
- Updated: 2026-06-20
- HTML: https://affpapa.org/en/nevibecode/skills/go-functions

## What it does

The skill organizes functions inside a Go file by a strict hierarchy. Types come first, followed by `NewXxx` constructors, exported functions, unexported functions, and plain utilities at the bottom. Functions are grouped by receiver and arranged in rough call order. When signatures exceed line limits, every parameter wraps onto its own line with a trailing comma.

It prevents passing pointers to interfaces because Go interfaces should pass by value. Format functions must end with the `f` suffix, or `go vet` checks will break. For logging and error messages, it mandates `%q` instead of manual quoting with `%s` to escape special characters safely.

This skill intentionally omits functional option constructors and error-handling patterns. If your code needs options like `WithTimeout`, install the separate `go-functional-options` skill instead.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add cxuu/golang-skills --skill go-functions -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/go-functions/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/go-functions/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add cxuu/golang-skills --skill go-functions -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/go-functions/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add cxuu/golang-skills --skill go-functions -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/go-functions/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install cxuu/golang-skills go-functions
```

2. **Manually: put the files in place**
- File: `.github/skills/go-functions/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add cxuu/golang-skills --skill go-functions -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/cxuu/golang-skills --path skills/go-functions
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/go-functions/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add cxuu/golang-skills --skill go-functions -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/cxuu/golang-skills/tree/HEAD/skills/go-functions/SKILL.md

## When to use it
- organize method declarations and constructors inside a Go file
- format multi-line Go function signatures with trailing commas
- ensure Printf-style functions pass go vet validation
- replace naked boolean function arguments with custom types

## Example prompts
- Reorder the functions in this Go file by receiver and call order
- Format this long Go function signature across multiple lines
- Refactor this Printf-style helper to follow Go formatting standards

## Source text · SKILL.md · Apache-2.0

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BEGIN THIRD-PARTY FILE 3f6875a70eec3a61
````text
---
name: go-functions
description: Use when organizing functions within a Go file, formatting function signatures, designing return values, or following Printf-style naming conventions. Also use when a user is adding or refactoring any Go function, even if they don't mention function design or signature formatting. Does not cover functional options constructors (see go-functional-options).
---

# Go Function Design

## Resource Routing

- `references/SIGNATURES.md` - Read when designing parameters, return values, named results, or signature readability.
- `references/PRINTF-STRINGER.md` - Read when using fmt verbs, Stringer, GoStringer, Formatter, or Printf-style function naming.

> **When this skill does NOT apply**: For functional options constructors (`WithTimeout`, `WithLogger`), see [go-functional-options](../go-functional-options/SKILL.md). For error return conventions, see [go-error-handling](../go-error-handling/SKILL.md). For naming functions and methods, see [go-naming](../go-naming/SKILL.md).

---

## Function Grouping and Ordering

Organize functions in a file by these rules:

1. Functions sorted in **rough call order**
2. Functions **grouped by receiver**
3. **Exported** functions appear first, after `struct`/`const`/`var` definitions
4. `NewXxx`/`newXxx` constructors appear right after the type definition
5. Plain utility functions appear toward the end of the file

```go
type something struct{ ... }

func newSomething() *something { return &something{} }

func (s *something) Cost() int { return calcCost(s.weights) }

func (s *something) Stop() { ... }

func calcCost(n []int) int { ... }
```

---

## Function Signatures

Keep the signature on a single line when possible. When it must wrap, put **all
arguments on their own lines** with a trailing comma:

```go
func (r *SomeType) SomeLongFunctionName(
    foo1, foo2, foo3 string,
    foo4, foo5, foo6 int,
) {
    foo7 := bar(foo1)
}
```

Add `/* name */` comments for ambiguous arguments, or better yet, replace naked
`bool` parameters with custom types.

---

## Pointers to Interfaces

You almost never need a pointer to an interface. Pass interfaces as values — the
underlying data can still be a pointer.

```go
// Bad: pointer to interface
func process(r *io.Reader) { ... }

// Good: pass the interface value
func process(r io.Reader) { ... }
```

---

## Printf and Stringer

### Printf-style Function Names

Functions that accept a format string should end in `f` for `go vet` support.
Declare format strings as `const` when used outside `Printf` calls.

Prefer `%q` over `%s` with manual quoting when formatting strings for logging
or error messages — it safely escapes special characters and wraps in quotes:

```go
return fmt.Errorf("unknown key %q", key) // produces: unknown key "foo\nbar"
```

See **go-functional-options** when designing a constructor with 3+ optional
parameters.

---

## Quick Reference

| Topic | Rule |
|-------|------|
````
END THIRD-PARTY FILE 3f6875a70eec3a61

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