Go naming

Go Naming Conventions

Go uses naming to encode visibility (UpperCamelCase = exported, lowerCamelCase = unexported), so naming is load-bearing — not cosmetic. Names should be short, contextual, and non-repetitive. The package name is always present at the call site; pretending otherwise is the single biggest source of bad Go names.

Core Rules

1. MixedCaps only. No underscores, no SCREAMING_SNAKE_CASE, no kHungarian. Exceptions: test subtests (TestFoo_BadInput), generated code, cgo.
2. Capitalization is visibility. Exported, unexported. Do not invent other conventions.
3. No stuttering. The package name is at the call site; http.HTTPClient is wrong, http.Client is right.
4. Scope drives length. i is fine in a 3-line loop; package-level vars need descriptive names.
5. Initialisms keep one case. userID, HTTPServer, ParseURL — never userId, HttpServer, ParseUrl.
6. Receivers are 1-2 letter abbreviations, consistent across all methods of the type. Never this/self.

Naming Decision Flow

What are you naming?
├─ Package        → lowercase single word, singular, specific (not util/common/helper)
├─ File           → lowercase, underscores OK (user_handler.go)
├─ Interface      → method + "-er" when single-method (Reader, Closer, Stringer)
├─ Struct/Type    → MixedCaps noun (Request, FileHeader)
├─ Constructor    → New() if package has one primary type; NewThing() if multiple
├─ Constant       → MixedCaps; never ALL_CAPS; role-based not value-based
├─ Enum (iota)    → type-prefix + Unknown/Invalid at position 0
├─ Sentinel error → ErrXxx (var ErrNotFound = errors.New("..."))
├─ Error type     → XxxError (type PathError struct{})
├─ Boolean field  → is/has/can prefix (isReady, hasPerm)
├─ Getter         → field name only (Owner()), never GetOwner()
├─ Setter         → SetXxx (SetOwner)
├─ Option         → WithXxx (WithLogger, WithPort)
├─ Variant        → WithContext suffix, In suffix (in-place), Must prefix (panics)
└─ Variable       → length proportional to scope distance

Quick Reference Table

Element	Convention	Example
Package	lowercase, singular	http, tabwriter
Exported	UpperCamelCase	ReadAll, HTTPClient
Unexported	lowerCamelCase	parseToken, userCount
Receiver	1-2 letters	func (s *Server)
Constant	MixedCaps	MaxRetries, defaultTimeout
Initialism	uniform case	URL, HTTPServer, xmlParser
Sentinel error	Err prefix	ErrNotFound
Error type	Error suffix	*PathError
Boolean field	is/has/can	isConnected
Option func	With + field	WithPort(8080)
Format func	f suffix	Errorf, Wrapf

Frequently Missed Conventions

These are correct but non-obvious — they account for most naming mistakes in code review.

Constructor: New vs NewThing

If the package exports one primary type, the constructor is New(). Callers write apiclient.New(), not apiclient.NewClient(). Only use NewThing when the package builds several things (http.NewRequest, http.NewServeMux).

Boolean Fields Get a Prefix

Unexported boolean fields use is/has/can. A bare adjective is ambiguous — is connected a method or a field, a state or a verb past tense?

type Conn struct { isOpen bool }
func (c *Conn) IsOpen() bool { return c.isOpen }

Error Strings Are Fully Lowercase

Including acronyms. Errors get concatenated: fmt.Errorf("parsing token: %w", err) becomes "parsing token: invalid message id". Mid-sentence capitals look wrong. Use "invalid message id" not "invalid message ID".

Sentinel errors should include the package name: errors.New("apiclient: not found").

Enum Zero Value Is a Sentinel

var s Status is silently 0. If 0 is StatusReady, uninitialised values look intentional. Put StatusUnknown (or Invalid) at iota 0.

type Status int
const (
    StatusUnknown Status = iota // zero-value catch
    StatusReady
    StatusRunning
)

Subtest Names Are Lowercase Phrases

t.Run("valid id", ...) // not "Valid ID"
t.Run("empty input", ...)

Read references/types-errors-constants.md when naming new struct/interface/enum/error families.

MixedCaps Is Load-Bearing

MaxPacketSize    // good
userCount        // good
parseHTTPResponse // good

MAX_PACKET_SIZE  // wrong — Go reserves casing for visibility
max_packet_size  // wrong — snake_case
kMaxBufferSize   // wrong — Hungarian

Avoid Stuttering

The package name is always present at the call site.

// In package http
type Client struct{} // not HTTPClient — caller writes http.Client

// In package user
func New() *User // not NewUser — caller writes user.New()

// In package dbpool
type Pool struct{}    // not DBPool
type Option func()    // not PoolOption

Read references/identifiers-and-scope.md for receivers, variable scope rules, and import aliasing.

Avoid Built-In Names

Never shadow error, string, len, cap, append, copy, new, make, nil, iota. The compiler allows it; readers and tools do not.

Anti-Patterns

Mistake	Fix
MAX_RETRIES = 3 constant	MaxRetries = 3 — MixedCaps
GetName() string getter	Name() string — Go omits Get
HttpClient, UserId, ParseUrl	HTTPClient, UserID, ParseURL — uniform initialism case
this/self receiver	One-letter abbreviation (s for Server)
util, common, helpers package	Specific name that describes content (stringutil, httpauth)
user.NewUser() constructor	user.New() — drop the type name
connected bool field	isConnected bool — prefix reads as a question
"invalid message ID" error	"invalid message id" — fully lowercase
StatusReady at iota 0	Add StatusUnknown at 0
userSlice []User	users []User — types do not belong in names

Verification Checklist

• No identifier contains _ outside of test subtests, generated code, or cgo.
• No Get prefix on getters; setters use Set.
• Initialisms are uniform case (grep Url\|Http\|Json\|Xml\|Id\b in source).
• Receivers across one type all use the same short name.
• All sentinel errors are ErrXxx; all error types are *XxxError.
• All iota-based enums place a Unknown/Invalid value at position 0.
• No package named util, common, helpers, misc.

Enforce With Linters

Most rules are mechanical and a linter will catch them in CI:

• revive — var-naming, exported, receiver-naming, error-naming.
• predeclared — flags identifiers that shadow built-ins.
• errname — enforces ErrXxx / *XxxError.
• misspell — keeps comments and identifiers consistent.

Add them to .golangci.yml and run golangci-lint run in CI.

References

• references/identifiers-and-scope.md — receivers, scope-based length, acronyms, import aliasing
• references/types-errors-constants.md — interfaces, structs, enums, sentinel vs typed errors
• references/functions-and-options.md — constructors, getters, variants, functional options