go-stringer-gen

This tool is a programmatic wrapper for standard stringer utility. Unlike the basic CLI, go-stringer-gen can be configured to handle multiple packages or types with distinct options in a single pass.

go-stringer-gen can be used as a standalone CLI tool or integrated into your own custom generator as a library. This is a component of my code generation toolbox.

Requirements

When running as a standalone generator, go-stringer-gen requires the pkl binary to be available on your PATH. It is used at runtime to evaluate .pkl configuration files. You can install it via:

# macOS
brew install pkl

For other platforms, see pkl-lang installation docs.

Usage

As a standalone generator

First let's set up a golang module

module github.com/gen/project

go 1.24

pkl config

// file: stringer.pkl
amends "package://nhatp.com/go/stringer-gen/pkl@0.5.0#/Config.pkl"

packages {
  ["github.com/gen/project"] {
    types { "Pill" }
  }
}

source code

// file: input.go

package painkiller

type Pill int

const (
	Placebo Pill = iota
	Aspirin
	Ibuprofen
	Paracetamol
	Acetaminophen = Paracetamol
)

expected generated code

// golden-file: gen_stringer.go
// Code generated by go-stringer-gen - dev. DO NOT EDIT.

package painkiller

import "strconv"

// Unnamed variable used to ensure `import "strconv"` is generated, as it is required below.
var _ = strconv.FormatInt(0, 10)

// --- Code generated by go run golang.org/x/tools/cmd/stringer@latest -type Pill -output /dev/stdout

func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[Placebo-0]
	_ = x[Aspirin-1]
	_ = x[Ibuprofen-2]
	_ = x[Paracetamol-3]
}

const _Pill_name = "PlaceboAspirinIbuprofenParacetamol"

var _Pill_index = [...]uint8{0, 7, 14, 23, 34}

func (i Pill) String() string {
	idx := int(i) - 0
	if i < 0 || idx >= len(_Pill_index)-1 {
		return "Pill(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _Pill_name[_Pill_index[idx]:_Pill_index[idx+1]]
}

// --- End code generated by go run golang.org/x/tools/cmd/stringer@latest -type Pill -output /dev/stdout

As a library

Example code

package yourgenerator

import (
	"fmt"

	"nhatp.com/go/stringer-gen"
)

func UseAsLibrary(sourceDir string) {
	// fileManager instance can be shared between commands in the toolbox
	fileManager := stringergen.NewFileManager(sourceDir, stringergen.WithBinaryName("your-generator"))
	
	var configs []stringergen.Config // build your configs here ...

	generator := stringergen.New(fileManager)

	pkgs, err := stringergen.LoadPackages(sourceDir)
	if err != nil {
		panic(err)
	}

	for _, pkg := range pkgs {
		if err := generator.Generate(pkg, configs); err != nil {
			panic(err)
		}
	}

	fmt.Println(fileManager.Files())
}

Features

Explore the features directory to see how go-stringer-gen handles various real-world scenarios:

• configs types, line comments or trim prefixed
• config multiple types with different configuration

Contributing & License

PRs are welcome! See the CONTRIBUTING. Distributed under the Apache License 2.0.

If you like the project, feel free to buy me a coffee. Thank you!