add support for time.Duration fields

parse.go

@@ -5,7 +5,6 @@ import (
 	"fmt"
 	"os"
 	"reflect"
-	"strconv"
 	"strings"
 )
 
@@ -329,42 +328,3 @@ func setSlice(dest reflect.Value, values []string) error {
 	}
 	return nil
 }
-
-// set a value from a string
-func setScalar(v reflect.Value, s string) error {
-	if !v.CanSet() {
-		return fmt.Errorf("field is not exported")
-	}
-
-	switch v.Kind() {
-	case reflect.String:
-		v.Set(reflect.ValueOf(s))
-	case reflect.Bool:
-		x, err := strconv.ParseBool(s)
-		if err != nil {
-			return err
-		}
-		v.Set(reflect.ValueOf(x))
-	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		x, err := strconv.ParseInt(s, 10, v.Type().Bits())
-		if err != nil {
-			return err
-		}
-		v.Set(reflect.ValueOf(x).Convert(v.Type()))
-	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
-		x, err := strconv.ParseUint(s, 10, v.Type().Bits())
-		if err != nil {
-			return err
-		}
-		v.Set(reflect.ValueOf(x).Convert(v.Type()))
-	case reflect.Float32, reflect.Float64:
-		x, err := strconv.ParseFloat(s, v.Type().Bits())
-		if err != nil {
-			return err
-		}
-		v.Set(reflect.ValueOf(x).Convert(v.Type()))
-	default:
-		return fmt.Errorf("not a scalar type: %s", v.Kind())
-	}
-	return nil
-}

parse_test.go

@@ -4,6 +4,7 @@ import (
 	"os"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -17,7 +18,7 @@ func parse(cmdline string, dest interface{}) error {
 	return p.Parse(strings.Split(cmdline, " "))
 }
 
-func TestStringSingle(t *testing.T) {
+func TestString(t *testing.T) {
 	var args struct {
 		Foo string
 	}
@@ -26,6 +27,42 @@ func TestStringSingle(t *testing.T) {
 	assert.Equal(t, "bar", args.Foo)
 }
 
+func TestInt(t *testing.T) {
+	var args struct {
+		Foo int
+	}
+	err := parse("--foo 7", &args)
+	require.NoError(t, err)
+	assert.EqualValues(t, 7, args.Foo)
+}
+
+func TestUint(t *testing.T) {
+	var args struct {
+		Foo uint
+	}
+	err := parse("--foo 7", &args)
+	require.NoError(t, err)
+	assert.EqualValues(t, 7, args.Foo)
+}
+
+func TestFloat(t *testing.T) {
+	var args struct {
+		Foo float32
+	}
+	err := parse("--foo 3.4", &args)
+	require.NoError(t, err)
+	assert.EqualValues(t, 3.4, args.Foo)
+}
+
+func TestDuration(t *testing.T) {
+	var args struct {
+		Foo time.Duration
+	}
+	err := parse("--foo 3ms", &args)
+	require.NoError(t, err)
+	assert.Equal(t, 3*time.Millisecond, args.Foo)
+}
+
 func TestMixed(t *testing.T) {
 	var args struct {
 		Foo  string `arg:"-f"`

scalar.go

@@ -0,0 +1,63 @@
+package arg
+
+import (
+	"encoding"
+	"fmt"
+	"reflect"
+	"strconv"
+	"time"
+)
+
+var (
+	durationType        = reflect.TypeOf(time.Duration(0))
+	textUnmarshalerType = reflect.TypeOf([]encoding.TextUnmarshaler{}).Elem()
+)
+
+// set a value from a string
+func setScalar(v reflect.Value, s string) error {
+	if !v.CanSet() {
+		return fmt.Errorf("field is not exported")
+	}
+
+	// If we have a time.Duration then use time.ParseDuration
+	if v.Type() == durationType {
+		x, err := time.ParseDuration(s)
+		if err != nil {
+			return err
+		}
+		v.Set(reflect.ValueOf(x))
+		return nil
+	}
+
+	switch v.Kind() {
+	case reflect.String:
+		v.SetString(s)
+	case reflect.Bool:
+		x, err := strconv.ParseBool(s)
+		if err != nil {
+			return err
+		}
+		v.SetBool(x)
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		x, err := strconv.ParseInt(s, 10, v.Type().Bits())
+		if err != nil {
+			return err
+		}
+		v.SetInt(x)
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		x, err := strconv.ParseUint(s, 10, v.Type().Bits())
+		if err != nil {
+			return err
+		}
+		v.SetUint(x)
+	case reflect.Float32, reflect.Float64:
+		x, err := strconv.ParseFloat(s, v.Type().Bits())
+		if err != nil {
+			return err
+		}
+		v.SetFloat(x)
+	default:
+		return fmt.Errorf("not a scalar type: %s", v.Kind())
+	}
+	return nil
+}