With strings.Replacer

使用 strings.Replacer，实现您的格式化程序欲望非常简单和紧凑.

With strings.Replacer

Using strings.Replacer, implementing a formatter of your desire is very easy and compact.

func main() {
    file, err := "/data/test.txt", "file not found"

    log("File {file} had error {error}", "{file}", file, "{error}", err)
}

func log(format string, args ...string) {
    r := strings.NewReplacer(args...)
    fmt.Println(r.Replace(format))
}

输出(在 Go Playground 上试试):

Output (try it on the Go Playground):

File /data/test.txt had error file not found

我们可以通过在log()函数中自动为参数名称添加括号来使其使用起来更愉快:

We can make it more pleasant to use by adding the brackets to the parameter names automatically in the log() function:

func main() {
    file, err := "/data/test.txt", "file not found"

    log2("File {file} had error {error}", "file", file, "error", err)
}

func log2(format string, args ...string) {
    for i, v := range args {
        if i%2 == 0 {
            args[i] = "{" + v + "}"
        }
    }
    r := strings.NewReplacer(args...)
    fmt.Println(r.Replace(format))
}

输出(在 Go Playground 上试试):

Output (try it on the Go Playground):

File /data/test.txt had error file not found

是的，您可以说这仅接受 string 参数值.这是真实的.再改进一点，就不会这样了:

Yes, you could say that this only accepts string parameter values. This is true. With a little more improvement, this won't be true:

func main() {
    file, err := "/data/test.txt", 666

    log3("File {file} had error {error}", "file", file, "error", err)
}

func log3(format string, args ...interface{}) {
    args2 := make([]string, len(args))
    for i, v := range args {
        if i%2 == 0 {
            args2[i] = fmt.Sprintf("{%v}", v)
        } else {
            args2[i] = fmt.Sprint(v)
        }
    }
    r := strings.NewReplacer(args2...)
    fmt.Println(r.Replace(format))
}

输出(在 Go Playground 上试试):

Output (try it on the Go Playground):

File /data/test.txt had error 666

此变体接受参数作为 map[string]interface{} 并将结果作为 string 返回:

A variant of this to accept params as a map[string]interface{} and return the result as a string:

type P map[string]interface{}

func main() {
    file, err := "/data/test.txt", 666

    s := log33("File {file} had error {error}", P{"file": file, "error": err})
    fmt.Println(s)
}

func log33(format string, p P) string {
    args, i := make([]string, len(p)*2), 0
    for k, v := range p {
        args[i] = "{" + k + "}"
        args[i+1] = fmt.Sprint(v)
        i += 2
    }
    return strings.NewReplacer(args...).Replace(format)
}

在 Go Playground 上试试.

您的模板解决方案或提案也过于冗长.它可以写成这样紧凑(省略错误检查):

Your template solution or proposal is also way too verbose. It can be written as compact as this (error checks omitted):

type P map[string]interface{}

func main() {
    file, err := "/data/test.txt", 666

    log4("File {{.file}} has error {{.error}}", P{"file": file, "error": err})
}

func log4(format string, p P) {
    t := template.Must(template.New("").Parse(format))
    t.Execute(os.Stdout, p)
}

输出(在 Go Playground 上试试):

Output (try it on the Go Playground):

File /data/test.txt has error 666

如果您想返回 string(而不是将其打印到标准输出)，您可以这样做(在 去游乐场):

If you want to return the string (instead of printing it to the standard output), you may do it like this (try it on the Go Playground):

func log5(format string, p P) string {
    b := &bytes.Buffer{}
    template.Must(template.New("").Parse(format)).Execute(b, p)
    return b.String()
}

使用显式参数索引

这在另一个答案中已经提到过，但要完成它，请知道相同的显式参数索引可能会被使用任意多次，从而导致多次替换相同的参数.在这个问题中阅读更多相关信息:用相同的变量替换 Sprintf 中的所有变量