rename PostSet to SetV and split the dynamic log level example/code

Author: ldemailly

dyngeneric.go

@@ -225,10 +225,14 @@ func (d *DynValue[T]) Set(rawInput string) error {
 	if err != nil {
 		return err
 	}
-	return d.PostSet(val)
+	return d.SetV(val)
 }
 
-func (d *DynValue[T]) PostSet(val T) error {
+// SetV is for when the value is already parsed/of the correct type.
+// Validators and notifiers are triggered (only input mutator and parsing from string is skipped).
+// Ideally this would be called Set() and the other SetAsString() but
+// the flag api needs Set() to be the one taking a string.
+func (d *DynValue[T]) SetV(val T) error {
 	if d.mutator != nil {
 		val = d.mutator(val)
 	}

dynjson.go

@@ -57,7 +57,7 @@ func (d *DynJSONValue) Set(rawInput string) error {
 	if err := json.Unmarshal([]byte(input), val); err != nil {
 		return err
 	}
-	return d.PostSet(val)
+	return d.SetV(val)
 }
 
 // String returns the canonical string representation of the type.

dynloglevel/dynloglevel.go

@@ -35,8 +35,9 @@ func LoggerFlagSetup() {
 		return // avoid redefining flag/make it ok for multiple function to init this.
 	}
 	// virtual dynLevel flag that maps back to actual level
-	_ = dflag.DynString(flag.CommandLine, "loglevel", log.GetLogLevel().String(),
-		fmt.Sprintf("loglevel, one of %v", log.LevelToStrA)).WithInputMutator(
+	defVal := log.GetLogLevel().String()
+	usage := fmt.Sprintf("`loglevel`, one of %v", log.LevelToStrA)
+	flag := dflag.New(defVal, usage).WithInputMutator(
 		func(inp string) string {
 			// The validation map has full lowercase and capitalized first letter version
 			return strings.ToLower(strings.TrimSpace(inp))
@@ -48,6 +49,7 @@ func LoggerFlagSetup() {
 		func(old, newStr string) {
 			_ = log.SetLogLevelStr(newStr) // will succeed as we just validated it first
 		})
+	dflag.Flag("loglevel", flag)
 	done = true
 }