使用strings.Replacer
,实现您所需的格式化程序非常容易且紧凑。
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上尝试):
File /data/test.txt had error file not found
通过在log()
函数中自动在参数名称中添加方括号,可以使使用起来更加愉快:
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上尝试):
File /data/test.txt had error file not found
是的,您可以说这仅接受string
参数值。这是真的。有了更多的改进,这将不是真的:
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上尝试):
File /data/test.txt had error 666
此方法的一种变体,接受params作为a map[string]interface{}
并以a形式返回结果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上尝试一下。
您的模板解决方案或建议也太冗长。可以这样紧凑地编写(省略错误检查):
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上尝试):
File /data/test.txt has error 666
如果要返回string
(而不是将其打印到标准输出),则可以这样做(在Go Playground上尝试):
func log5(format string, p P) string {
b := &bytes.Buffer{}
template.Must(template.New("").Parse(format)).Execute(b, p)
return b.String()
}
在另一个答案中已经提到了这一点,但是要完成此操作,请知道相同的显式参数索引可以任意使用多次,从而导致同一参数被多次替换。