如何在Go中打印“枚举”的字符串表示形式？

Question

I've looked at the various official sources for how to do this but I can't find it. Imagine you have the following enum (I know golang doesn't have enums in the classic sense):

package main

import "fmt"

type LogLevel int

const (
    Off LogLevel = iota
    Debug
)

var level LogLevel = Debug

func main() {
    fmt.Printf("Log Level: %s", level)
}

The closest I can get with the above %s, which gives me:

Log Level: %!s(main.LogLevel=1)

I would like to have:

Log Level: Debug

Can anyone help me?

Answer 1

You can't directly within the language, but there's a tool for generating the supporting code: golang.org/x/tools/cmd/stringer

From the example in the stringer docs

type Pill int

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

Would produce code like

const _Pill_name = "PlaceboAspirinIbuprofenParacetamol"

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

func (i Pill) String() string {
    if i < 0 || i+1 >= Pill(len(_Pill_index)) {
        return fmt.Sprintf("Pill(%d)", i)
    }
    return _Pill_name[_Pill_index[i]:_Pill_index[i+1]]
}