首次提交：初始化项目代码

flag/enum_validation.go

@@ -0,0 +1,51 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"strings"
+)
+
+// Environment 运行环境枚举类型
+type Environment string
+
+const (
+	EnvDev  Environment = "dev"
+	EnvTest Environment = "test"
+	EnvProd Environment = "prod"
+)
+
+// 合法环境白名单
+var validEnvs = map[Environment]bool{
+	EnvDev:  true,
+	EnvTest: true,
+	EnvProd: true,
+}
+
+func (e *Environment) Set(s string) error {
+	env := Environment(strings.ToLower(s))
+	if !validEnvs[env] {
+		return fmt.Errorf("无效运行环境，仅支持 dev/test/prod")
+	}
+	*e = env
+	return nil
+}
+
+func (e *Environment) String() string {
+	if *e == "" {
+		return string(EnvDev)
+	}
+	return string(*e)
+}
+
+func (e *Environment) Get() any {
+	return *e
+}
+
+func main() {
+	var env Environment = EnvDev // 默认值为 dev
+	flag.Var(&env, "env", "运行环境：dev/test/prod")
+	flag.Parse()
+
+	fmt.Printf("当前运行环境：%s\n", env)
+}