Add TextFlag

flag_text.go

@@ -0,0 +1,53 @@
+package cli
+
+import (
+	"encoding"
+)
+
+type TextMarshalUnmarshaler interface {
+	encoding.TextMarshaler
+	encoding.TextUnmarshaler
+}
+
+// TextFlag enables you to set types that satisfies [TextMarshalUnmarshaler] using flags such as log levels.
+type TextFlag = FlagBase[TextMarshalUnmarshaler, NoConfig, TextValue]
+
+type TextValue struct {
+	Value TextMarshalUnmarshaler
+}
+
+func (f TextValue) String() string {
+	text, err := f.Value.MarshalText()
+	if err != nil {
+		return ""
+	}
+
+	return string(text)
+}
+
+func (f TextValue) Set(s string) error {
+	return f.Value.UnmarshalText([]byte(s))
+}
+
+func (f TextValue) Get() any {
+	return f.Value
+}
+
+func (f TextValue) Create(v TextMarshalUnmarshaler, p *TextMarshalUnmarshaler, _ NoConfig) Value {
+	pp := *p
+	if v != nil {
+		if b, err := v.MarshalText(); err == nil {
+			_ = pp.UnmarshalText(b)
+		}
+	}
+
+	return &TextValue{
+		Value: pp,
+	}
+}
+
+func (f TextValue) ToString(v TextMarshalUnmarshaler) string {
+	text, _ := v.MarshalText()
+
+	return string(text)
+}

flag_text_test.go

@@ -0,0 +1,168 @@
+package cli
+
+import (
+	"encoding"
+	"errors"
+	"io"
+	"log/slog"
+	"slices"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+type badMarshaller struct{}
+
+func (badMarshaller) UnmarshalText(_ []byte) error {
+	return nil
+}
+
+func (badMarshaller) MarshalText() ([]byte, error) {
+	return nil, errors.New("bad")
+}
+
+func ptr[T any](v T) *T {
+	return &v
+}
+
+func TestTextFlag(t *testing.T) {
+	tests := []struct {
+		name    string
+		flag    *TextFlag
+		args    []string
+		want    string
+		wantErr bool
+	}{
+		{
+			name: "empty",
+			flag: &TextFlag{
+				Name:        "log-level",
+				Value:       &slog.LevelVar{},
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
+			},
+			want: "INFO",
+		},
+		{
+			name: "info",
+			flag: &TextFlag{
+				Name:        "log-level",
+				Value:       &slog.LevelVar{},
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
+				Validator: func(v TextMarshalUnmarshaler) error {
+					text, err := v.MarshalText()
+					if err != nil {
+						return err
+					}
+
+					if !slices.Equal(text, []byte("INFO")) {
+						return errors.New("expected \"INFO\"")
+					}
+
+					return nil
+				},
+			},
+			args: []string{"--log-level", "info"},
+			want: "INFO",
+		},
+		{
+			name: "debug",
+			flag: &TextFlag{
+				Name:        "log-level",
+				Value:       &slog.LevelVar{},
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
+			},
+			args: []string{"--log-level", "debug"},
+			want: "DEBUG",
+		},
+		{
+			name: "invalid",
+			flag: &TextFlag{
+				Name:        "log-level",
+				Value:       &slog.LevelVar{},
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
+			},
+			args:    []string{"--log-level", "invalid"},
+			want:    "INFO",
+			wantErr: true,
+		},
+		{
+			name: "bad_marshaller",
+			flag: &TextFlag{
+				Name:        "text",
+				Value:       &badMarshaller{},
+				Destination: ptr[TextMarshalUnmarshaler](&badMarshaller{}),
+			},
+			args:    []string{"--text", "foo"},
+			wantErr: true,
+		},
+		{
+			name: "default",
+			flag: &TextFlag{
+				Name: "log-level",
+				Value: func() *slog.LevelVar {
+					var l slog.LevelVar
+
+					l.Set(slog.LevelWarn)
+
+					return &l
+				}(),
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
+			},
+			args: []string{},
+			want: "WARN",
+		},
+		{
+			name: "override_default",
+			flag: &TextFlag{
+				Name: "log-level",
+				Value: func() *slog.LevelVar {
+					var l slog.LevelVar
+
+					l.Set(slog.LevelWarn)
+
+					return &l
+				}(),
+				Destination: ptr[TextMarshalUnmarshaler](&slog.LevelVar{}),
+			},
+			args: []string{"--log-level", "error"},
+			want: "ERROR",
+		},
+	}
+
+	t.Parallel()
+
+	for _, tt := range tests {
+		t.Parallel()
+
+		t.Run(tt.name, func(t *testing.T) {
+			cmd := &Command{
+				Name:      tt.name,
+				Flags:     []Flag{tt.flag},
+				Writer:    io.Discard,
+				ErrWriter: io.Discard,
+			}
+
+			err := cmd.Run(buildTestContext(t), append([]string{"mock"}, tt.args...))
+
+			if err != nil && !tt.wantErr {
+				require.NoError(t, err)
+
+				return
+			} else if err != nil {
+				return
+			}
+
+			var got []byte
+
+			got, err = tt.flag.Get().(encoding.TextMarshaler).MarshalText()
+			if tt.wantErr {
+				require.Error(t, err)
+
+				return
+			}
+
+			assert.Equal(t, tt.want, string(got))
+		})
+	}
+}

godoc-current.txt

@@ -1347,6 +1347,29 @@ type SuggestCommandFunc func(commands []*Command, provided string) string
 
 type SuggestFlagFunc func(flags []Flag, provided string, hideHelp bool) string
 
+type TextFlag = FlagBase[TextMarshalUnmarshaler, NoConfig, TextValue]
+    TextFlag enables you to set types that satisfies TextMarshalUnmarshaler
+    using flags such as log levels.
+
+type TextMarshalUnmarshaler interface {
+	encoding.TextMarshaler
+	encoding.TextUnmarshaler
+}
+
+type TextValue struct {
+	Value TextMarshalUnmarshaler
+}
+
+func (f TextValue) Create(v TextMarshalUnmarshaler, p *TextMarshalUnmarshaler, _ NoConfig) Value
+
+func (f TextValue) Get() any
+
+func (f TextValue) Set(s string) error
+
+func (f TextValue) String() string
+
+func (f TextValue) ToString(v TextMarshalUnmarshaler) string
+
 type TimestampArg = ArgumentBase[time.Time, TimestampConfig, timestampValue]
 
 type TimestampArgs = ArgumentsBase[time.Time, TimestampConfig, timestampValue]

testdata/godoc-v3.x.txt

@@ -1347,6 +1347,29 @@ type SuggestCommandFunc func(commands []*Command, provided string) string
 
 type SuggestFlagFunc func(flags []Flag, provided string, hideHelp bool) string
 
+type TextFlag = FlagBase[TextMarshalUnmarshaler, NoConfig, TextValue]
+    TextFlag enables you to set types that satisfies TextMarshalUnmarshaler
+    using flags such as log levels.
+
+type TextMarshalUnmarshaler interface {
+	encoding.TextMarshaler
+	encoding.TextUnmarshaler
+}
+
+type TextValue struct {
+	Value TextMarshalUnmarshaler
+}
+
+func (f TextValue) Create(v TextMarshalUnmarshaler, p *TextMarshalUnmarshaler, _ NoConfig) Value
+
+func (f TextValue) Get() any
+
+func (f TextValue) Set(s string) error
+
+func (f TextValue) String() string
+
+func (f TextValue) ToString(v TextMarshalUnmarshaler) string
+
 type TimestampArg = ArgumentBase[time.Time, TimestampConfig, timestampValue]
 
 type TimestampArgs = ArgumentsBase[time.Time, TimestampConfig, timestampValue]