support unknown flag

Author: yangxikun

flag.go

@@ -85,7 +85,35 @@ func (f *FlagLoader) Load(s interface{}) error {
 		args = f.Args
 	}
 
-	return flagSet.Parse(args)
+	// support unknown flag
+	var newArgs []string
+	type BoolFlag interface {
+		IsBoolFlag() bool
+	}
+	for i := 0; i < len(args); i++ {
+		if strings.HasPrefix(args[i], "-") {
+			flagName := strings.TrimLeft(args[i], "-")
+			if flagName == "help" || flagName == "h" {
+				newArgs = append(newArgs, args[i])
+				continue
+			}
+			cmdlineFlag := f.flagSet.Lookup(flagName)
+			if cmdlineFlag != nil  {
+				newArgs = append(newArgs, args[i])
+				if bf, ok := cmdlineFlag.Value.(BoolFlag); ok && bf.IsBoolFlag() {
+					continue
+				}
+				i++
+				if i < len(args) {
+					newArgs = append(newArgs, args[i])
+				}
+			}
+		}
+	}
+
+	fmt.Println(newArgs)
+
+	return flagSet.Parse(newArgs)
 }
 
 func filterArgs(args []string) []string {