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Type safe enums for Go without code generation or reflection.

😎 Features:

• Type-safe, thanks to generics.
• No code generation.
• No reflection.
• Well-documented, with working examples for every function.
• Flexible, supports both static and runtime definitions.
• Zero-dependency.

go get github.com/orsinium-labs/enum

Define:

type Color enum.Member[string]

var (
  Red    = Color{"red"}
  Green  = Color{"green"}
  Blue   = Color{"blue"}
  Colors = enum.New(Red, Green, Blue)
)

Parse a raw value (nil is returned for invalid value):

parsed := Colors.Parse("red")

Compare enum members:

parsed == Red
Red != Green

Accept enum members as function arguments:

func SetPixel(x, i int, c Color)

Loop over all enum members:

for _, color := range Colors.Members() {
  // ...
}

Ensure that the enum member belongs to an enum (can be useful for defensive programming to ensure that the caller doesn't construct an enum member manually):

func f(color Color) {
  if !colors.Contains(color) {
    panic("invalid color")
  }
  // ...
}

Define custom methods on enum members:

func (c Color) UnmarshalJSON(b []byte) error {
  return nil
}

Dynamically create enums to pass multiple members in a function:

func SetPixel2(x, y int, colors enum.Enum[Color, string]) {
  if colors.Contains(Red) {
    // ...
  }
}

purple := enum.New(Red, Blue)
SetPixel2(0, 0, purple)

Enum members can be any comparable type, not just strings:

type ColorValue struct {
  UI string
  DB int
}
type Color enum.Member[ColorValue]
var (
  Red    = Color{ColorValue{"red", 1}}
  Green  = Color{ColorValue{"green", 2}}
  Blue   = Color{ColorValue{"blue", 3}}
  Colors = enum.New(Red, Green, Blue)
)

fmt.Println(Red.Value.UI)

If the enum has lots of members and new ones may be added over time, it's easy to forget to register all members in the enum. To prevent this, use enum.Builder to define an enum:

type Color enum.Member[string]

var (
  b      = enum.NewBuilder[string, Color]()
  Red    = b.Add(Color{"red"})
  Green  = b.Add(Color{"green"})
  Blue   = b.Add(Color{"blue"})
  Colors = b.Enum()
)

1. What happens when enums are added in Go itself? I'll keep it alive until someone uses it but I expect the project popularity to quickly die out when there is native language support for enums. When you can mess with the compiler itself, you can do more. For example, this package can't provide an exhaustiveness check for switch statements using enums (maybe only by implementing a linter) but proper language-level enums would most likely have it.
2. Is it reliable? Yes, pretty much. It has good tests but most importantly it's a small project with just a bit of the actual code that is hard to mess up.
3. Is it maintained? The project is pretty much feature-complete, so there is nothing for me to commit and release daily. However, I accept contributions (see below).
4. What if I found a bug? Fork the project, fix the bug, write some tests, and open a Pull Request. I usually merge and release any contributions within a day.