using own usage func

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

flag.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"os"
 	"reflect"
+	"strings"
 	"time"
 
 	"go.unistack.org/micro/v3/config"
@@ -30,6 +31,8 @@ var (
 type flagConfig struct {
 	fset *flag.FlagSet
 	opts config.Options
+	name string
+	env  string
 }
 
 func (c *flagConfig) Options() config.Options {
@@ -40,19 +43,23 @@ func (c *flagConfig) Init(opts ...config.Option) error {
 	for _, o := range opts {
 		o(&c.opts)
 	}
+	c.configure()
 
 	fields, err := rutil.StructFields(c.opts.Struct)
 	if err != nil {
 		return err
 	}
 
-	// flag.CommandLine.Init(os.Args[0], flag.ContinueOnError)
 	for _, sf := range fields {
 		tf, ok := sf.Field.Tag.Lookup(c.opts.StructTag)
 		if !ok {
 			continue
 		}
+
 		fn, fd, fv := getFlagOpts(tf)
+		if tf, ok = sf.Field.Tag.Lookup(c.env); ok {
+			fd += fmt.Sprintf(" (env %s)", tf)
+		}
 
 		rcheck := true
 
@@ -67,7 +74,6 @@ func (c *flagConfig) Init(opts ...config.Option) error {
 			return nil
 		}
 
-		fmt.Printf("register %s flag\n", fn)
 		switch vi.(type) {
 		case time.Duration:
 			err = c.flagDuration(sf.Value, fn, fv, fd)
@@ -149,42 +155,125 @@ func (c *flagConfig) Watch(ctx context.Context, opts ...config.WatchOption) (con
 	return nil, fmt.Errorf("not implemented")
 }
 
+func (c *flagConfig) usage() {
+	mapDelim := DefaultMapDelim
+	sliceDelim := DefaultSliceDelim
+
+	if c.opts.Context != nil {
+		if d, ok := c.opts.Context.Value(mapDelimKey{}).(string); ok {
+			mapDelim = d
+		}
+		if d, ok := c.opts.Context.Value(sliceDelimKey{}).(string); ok {
+			sliceDelim = d
+		}
+	}
+
+	if c.name == "" {
+		fmt.Fprintf(c.fset.Output(), "Usage:\n")
+	} else {
+		fmt.Fprintf(c.fset.Output(), "Usage of %s:\n", c.name)
+	}
+
+	c.fset.VisitAll(func(f *flag.Flag) {
+		var b strings.Builder
+		fmt.Fprintf(&b, "  -%s", f.Name) // Two spaces before -; see next two comments.
+		_, usage := flag.UnquoteUsage(f)
+		name := "value"
+		v := reflect.TypeOf(f.Value).String()
+		b.WriteString(" ")
+		switch v {
+		case "*flag.boolFlag":
+			name = "bool"
+		case "*flag.durationValue":
+			name = "duration"
+		case "*flag.float64Value":
+			name = "float"
+		case "*flag.intValue", "*flag.int64Value":
+			name = "int"
+		case "*flag.stringValue":
+			name = "string"
+		case "*flag.uintValue", "*flag.uint64Value":
+			name = "uint"
+		case "*flag.mapValue":
+			//	nv := f.Value.(*mapValue)
+			name = fmt.Sprintf("string key=val with %q as separator", mapDelim)
+		case "*flag.sliceValue":
+			//	nv := f.Value.(*sliceValue)
+			name = fmt.Sprintf("string with %q as separator", sliceDelim)
+		}
+		b.WriteString(name)
+
+		// Boolean flags of one ASCII letter are so common we
+		// treat them specially, putting their usage on the same line.
+		if b.Len() <= 4 { // space, space, '-', 'x'.
+			b.WriteString("\t")
+		} else {
+			// Four spaces before the tab triggers good alignment
+			// for both 4- and 8-space tab stops.
+			b.WriteString("\n    \t")
+		}
+		b.WriteString(strings.ReplaceAll(usage, "\n", "\n    \t"))
+
+		if rutil.IsZero(f.Value) || f.Value.String() == f.DefValue {
+			fmt.Fprintf(&b, " (default %q)", f.DefValue)
+		} else {
+			fmt.Fprintf(&b, " (default %q current %q)", f.DefValue, f.Value)
+		}
+
+		fmt.Fprint(c.fset.Output(), b.String(), "\n")
+	})
+}
+
+func (c *flagConfig) configure() {
+	flagSet := flag.CommandLine
+	flagSetName := os.Args[0]
+	flagSetErrorHandling := flag.ExitOnError
+	flagEnv := "env"
+	var flagUsage func()
+	var isSet bool
+
+	if c.opts.Context != nil {
+		if v, ok := c.opts.Context.Value(flagSetNameKey{}).(string); ok {
+			isSet = true
+			flagSetName = v
+		}
+		if v, ok := c.opts.Context.Value(flagSetErrorHandlingKey{}).(flag.ErrorHandling); ok {
+			isSet = true
+			flagSetErrorHandling = v
+		}
+		if v, ok := c.opts.Context.Value(flagSetKey{}).(*flag.FlagSet); ok {
+			flagSet = v
+		}
+		if v, ok := c.opts.Context.Value(flagSetUsageKey{}).(func()); ok {
+			flagUsage = v
+		}
+		if v, ok := c.opts.Context.Value(flagEnvKey{}).(string); ok {
+			flagEnv = v
+		}
+	}
+	c.fset = flagSet
+
+	if isSet {
+		c.fset.Init(flagSetName, flagSetErrorHandling)
+	}
+	if flagUsage != nil {
+		c.fset.Usage = flagUsage
+	} else {
+		c.fset.Usage = c.usage
+	}
+	c.env = flagEnv
+
+	c.name = flagSetName
+}
+
 func NewConfig(opts ...config.Option) config.Config {
 	options := config.NewOptions(opts...)
 	if len(options.StructTag) == 0 {
 		options.StructTag = DefaultStructTag
 	}
-	flagSet := flag.CommandLine
-	flagSetName := os.Args[0]
-	flagSetErrorHandling := flag.ExitOnError
-	var flagUsage func()
-	var isSet bool
 
-	if options.Context != nil {
-		if v, ok := options.Context.Value(flagSetNameKey{}).(string); ok {
-			isSet = true
-			flagSetName = v
-		}
-		if v, ok := options.Context.Value(flagSetErrorHandlingKey{}).(flag.ErrorHandling); ok {
-			isSet = true
-			flagSetErrorHandling = v
-		}
-		if v, ok := options.Context.Value(flagSetKey{}).(*flag.FlagSet); ok {
-			flagSet = v
-		}
-		if v, ok := options.Context.Value(flagSetUsageKey{}).(func()); ok {
-			flagUsage = v
-		}
-	}
-
-	if isSet {
-		flagSet.Init(flagSetName, flagSetErrorHandling)
-	}
-	if flagUsage != nil {
-		flagSet.Usage = flagUsage
-	}
-
-	c := &flagConfig{opts: options, fset: flagSet}
+	c := &flagConfig{opts: options}
+	c.configure()
 
 	return c
 }

options.go

@@ -54,3 +54,11 @@ type flagSetUsageKey struct{}
 func FlagUsage(fn func()) config.Option {
 	return config.SetOption(flagSetUsageKey{}, fn)
 }
+
+
+type flagEnvKey struct{}
+
+// FlagEnv set flag set usage func
+func FlagEnv(n string) config.Option {
+	return config.SetOption(flagEnvKey{}, n)
+}

util.go

@@ -15,7 +15,7 @@ type mapValue struct {
 	v     reflect.Value
 }
 
-func (v mapValue) String() string {
+func (v *mapValue) String() string {
 	if v.v.Kind() != reflect.Invalid {
 		var kv []string
 		it := v.v.MapRange()
@@ -29,7 +29,11 @@ func (v mapValue) String() string {
 	return v.def
 }
 
-func (v mapValue) Set(s string) error {
+func (v *mapValue) Get() interface{} {
+return v.v.Interface()
+}
+
+func (v *mapValue) Set(s string) error {
 	ps := strings.Split(s, v.delim)
 	if len(ps) == 0 {
 		return nil
@@ -72,7 +76,7 @@ type sliceValue struct {
 	v     reflect.Value
 }
 
-func (v sliceValue) String() string {
+func (v *sliceValue) String() string {
 	if v.v.Kind() != reflect.Invalid {
 		var kv []string
 		for idx := 0; idx < v.v.Len(); idx++ {
@@ -83,7 +87,12 @@ func (v sliceValue) String() string {
 	return v.def
 }
 
-func (v sliceValue) Set(s string) error {
+
+func (v *sliceValue) Get() interface{} {
+	return v.v.Interface()
+	}
+
+func (v *sliceValue) Set(s string) error {
 	p := strings.Split(s, v.delim)
 	v.v.Set(reflect.MakeSlice(v.v.Type(), len(p), len(p)))
 	switch v.v.Type().Elem().Kind() {
@@ -398,3 +407,19 @@ func getFlagOpts(tf string) (string, string, string) {
 	}
 	return name, desc, def
 }
+
+
+
+func isZeroValue(f *flag.Flag, value string) bool {
+	// Build a zero value of the flag's Value type, and see if the
+	// result of calling its String method equals the value passed in.
+	// This works unless the Value type is itself an interface type.
+	typ := reflect.TypeOf(f.Value)
+	var z reflect.Value
+	if typ.Kind() == reflect.Pointer {
+		z = reflect.New(typ.Elem())
+	} else {
+		z = reflect.Zero(typ)
+	}
+	return value == z.Interface().(flag.Value).String()
+}