Merge pull request #55 from rjeczalik/flag-value

multiconfig: add partial support for flag.Value

flag_test.go

@@ -1,6 +1,8 @@
 package multiconfig
 
 import (
+	"flag"
+	"net/url"
 	"strings"
 	"testing"
 
@@ -120,6 +122,49 @@ func TestCustomUsageFunc(t *testing.T) {
 	}
 }
 
+type URL struct {
+	*url.URL
+}
+
+var _ flag.Value = (*URL)(nil)
+
+func (u *URL) Set(s string) error {
+	ur, err := url.Parse(s)
+	if err != nil {
+		return err
+	}
+	u.URL = ur
+	return nil
+}
+
+type Endpoint struct {
+	Private *URL `required:"true"`
+	Public  *URL `required:"true"`
+}
+
+func TestFlagValueSupport(t *testing.T) {
+	m := &FlagLoader{}
+
+	m.Args = []string{
+		"-private", "http://127.0.0.1/kloud/kite",
+		"-public", "http://127.0.0.1/kloud/kite",
+	}
+
+	var e Endpoint
+
+	if err := m.Load(&e); err != nil {
+		t.Fatalf("Load()=%s", err)
+	}
+
+	if e.Private.String() != m.Args[1] {
+		t.Fatalf("got %q, want %q", e.Private, m.Args[3])
+	}
+
+	if e.Public.String() != m.Args[3] {
+		t.Fatalf("got %q, want %q", e.Public, m.Args[3])
+	}
+}
+
 // getFlags returns a slice of arguments that can be passed to flag.Parse()
 func getFlags(t *testing.T, structName, prefix string) []string {
 	if structName == "" {

multiconfig.go

@@ -1,6 +1,7 @@
 package multiconfig
 
 import (
+	"flag"
 	"fmt"
 	"os"
 	"reflect"
@@ -114,6 +115,24 @@ func (d *DefaultLoader) MustValidate(conf interface{}) {
 // string value in a sane way and is usefulf or environment variables or flags
 // which are by nature in string types.
 func fieldSet(field *structs.Field, v string) error {
+	switch f := field.Value().(type) {
+	case flag.Value:
+		if v := reflect.ValueOf(field.Value()); v.IsNil() {
+			typ := v.Type()
+			if typ.Kind() == reflect.Ptr {
+				typ = typ.Elem()
+			}
+
+			if err := field.Set(reflect.New(typ).Interface()); err != nil {
+				return err
+			}
+
+			f = field.Value().(flag.Value)
+		}
+
+		return f.Set(v)
+	}
+
 	// TODO: add support for other types
 	switch field.Kind() {
 	case reflect.Bool: