Fix:(issue_2032) Support for post parse config loading

command.go

@@ -540,6 +540,12 @@ func (cmd *Command) Run(ctx context.Context, osArgs []string) (deferErr error) {
 		return nil
 	}
 
+	for _, flag := range cmd.Flags {
+		if err := flag.PostParse(); err != nil {
+			return err
+		}
+	}
+
 	if cmd.After != nil && !cmd.Root().shellCompletion {
 		defer func() {
 			if err := cmd.After(ctx, cmd); err != nil {

command_test.go

@@ -2306,6 +2306,10 @@ func (c *customBoolFlag) GetUsage() string {
 	return "usage"
 }
 
+func (c *customBoolFlag) PostParse() error {
+	return nil
+}
+
 func (c *customBoolFlag) Apply(set *flag.FlagSet) error {
 	set.String(c.Nombre, c.Nombre, "")
 	return nil

flag.go

@@ -104,6 +104,8 @@ type ActionableFlag interface {
 type Flag interface {
 	fmt.Stringer
 
+	PostParse() error
+
 	// Apply Flag settings to the given flag set
 	Apply(*flag.FlagSet) error
 

flag_bool_with_inverse.go

@@ -135,6 +135,20 @@ func (parent *BoolWithInverseFlag) inverseAliases() (aliases []string) {
 	return
 }
 
+func (parent *BoolWithInverseFlag) PostParse() error {
+	if parent.positiveFlag != nil {
+		if err := parent.positiveFlag.PostParse(); err != nil {
+			return err
+		}
+	}
+	if parent.negativeFlag != nil {
+		if err := parent.negativeFlag.PostParse(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func (parent *BoolWithInverseFlag) Apply(set *flag.FlagSet) error {
 	if parent.positiveFlag == nil {
 		parent.initialize()

flag_ext.go

@@ -6,6 +6,10 @@ type extFlag struct {
 	f *flag.Flag
 }
 
+func (e *extFlag) PostParse() error {
+	return nil
+}
+
 func (e *extFlag) Apply(fs *flag.FlagSet) error {
 	fs.Var(e.f.Value, e.f.Name, e.f.Usage)
 	return nil

flag_impl.go

@@ -98,35 +98,42 @@ func (f *FlagBase[T, C, V]) GetValue() string {
 	return fmt.Sprintf("%v", f.Value)
 }
 
-// Apply populates the flag given the flag set and environment
-func (f *FlagBase[T, C, V]) Apply(set *flag.FlagSet) error {
-	tracef("apply (flag=%[1]q)", f.Name)
-
-	// TODO move this phase into a separate flag initialization function
-	// if flag has been applied previously then it would have already been set
-	// from env or file. So no need to apply the env set again. However
-	// lots of units tests prior to persistent flags assumed that the
-	// flag can be applied to different flag sets multiple times while still
-	// keeping the env set.
-	if !f.applied || f.Local {
-		newVal := f.Value
+// PostParse populates the flag given the flag set and environment
+func (f *FlagBase[T, C, V]) PostParse() error {
+	tracef("postparse (flag=%[1]q)", f.Name)
 
+	if !f.hasBeenSet {
 		if val, source, found := f.Sources.LookupWithSource(); found {
-			tmpVal := f.creator.Create(f.Value, new(T), f.Config)
 			if val != "" || reflect.TypeOf(f.Value).Kind() == reflect.String {
-				if err := tmpVal.Set(val); err != nil {
+				if err := f.value.Set(val); err != nil {
 					return fmt.Errorf(
 						"could not parse %[1]q as %[2]T value from %[3]s for flag %[4]s: %[5]s",
 						val, f.Value, source, f.Name, err,
 					)
 				}
 			} else if val == "" && reflect.TypeOf(f.Value).Kind() == reflect.Bool {
-				_ = tmpVal.Set("false")
+				_ = f.value.Set("false")
 			}
 
-			newVal = tmpVal.Get().(T)
 			f.hasBeenSet = true
 		}
+	}
+
+	return nil
+}
+
+// Apply populates the flag given the flag set and environment
+func (f *FlagBase[T, C, V]) Apply(set *flag.FlagSet) error {
+	tracef("apply (flag=%[1]q)", f.Name)
+
+	// TODO move this phase into a separate flag initialization function
+	// if flag has been applied previously then it would have already been set
+	// from env or file. So no need to apply the env set again. However
+	// lots of units tests prior to persistent flags assumed that the
+	// flag can be applied to different flag sets multiple times while still
+	// keeping the env set.
+	if !f.applied || f.Local {
+		newVal := f.Value
 
 		if f.Destination == nil {
 			f.value = f.creator.Create(newVal, new(T), f.Config)

flag_test.go

@@ -772,6 +772,8 @@ func TestStringSliceFlagApply_UsesEnvValues_noDefault(t *testing.T) {
 	_ = fl.Apply(set)
 
 	err := set.Parse(nil)
+
+	_ = fl.PostParse()
 	assert.NoError(t, err)
 	assert.Equal(t, []string{"vincent van goat", "scape goat"}, set.Lookup("goat").Value.(flag.Getter).Get())
 }
@@ -785,6 +787,7 @@ func TestStringSliceFlagApply_UsesEnvValues_withDefault(t *testing.T) {
 	set := flag.NewFlagSet("test", 0)
 	_ = fl.Apply(set)
 	err := set.Parse(nil)
+	_ = fl.PostParse()
 	assert.NoError(t, err)
 	assert.Equal(t, []string{"vincent van goat", "scape goat"}, set.Lookup("goat").Value.(flag.Getter).Get())
 }
@@ -798,6 +801,8 @@ func TestStringSliceFlagApply_DefaultValueWithDestination(t *testing.T) {
 	_ = fl.Apply(set)
 
 	err := set.Parse([]string{})
+
+	_ = fl.PostParse()
 	assert.NoError(t, err)
 	assert.Equal(t, defValue, dest)
 }
@@ -1056,6 +1061,7 @@ func TestIntSliceFlagApply_UsesEnvValues_noDefault(t *testing.T) {
 	r := require.New(t)
 	r.NoError(fl.Apply(set))
 	r.NoError(set.Parse(nil))
+	r.NoError(fl.PostParse())
 	r.Equal([]int64{1, 2}, set.Lookup("goat").Value.(flag.Getter).Get())
 }
 
@@ -1068,6 +1074,7 @@ func TestIntSliceFlagApply_UsesEnvValues_withDefault(t *testing.T) {
 	r := require.New(t)
 	r.NoError(fl.Apply(set))
 	r.NoError(set.Parse(nil))
+	r.NoError(fl.PostParse())
 	r.Equal([]int64{3, 4}, val)
 	r.Equal([]int64{1, 2}, set.Lookup("goat").Value.(flag.Getter).Get())
 }
@@ -1081,6 +1088,7 @@ func TestIntSliceFlagApply_DefaultValueWithDestination(t *testing.T) {
 	_ = fl.Apply(set)
 
 	err := set.Parse([]string{})
+	assert.NoError(t, fl.PostParse())
 	assert.NoError(t, err)
 	assert.Equal(t, defValue, dest)
 }
@@ -1184,6 +1192,7 @@ func TestUintSliceFlagApply_UsesEnvValues_noDefault(t *testing.T) {
 	r.NoError(fl.Apply(set))
 
 	r.NoError(set.Parse(nil))
+	r.NoError(fl.PostParse())
 	r.Equal([]uint64{1, 2}, set.Lookup("goat").Value.(flag.Getter).Get().([]uint64))
 }
 
@@ -1195,6 +1204,7 @@ func TestUintSliceFlagApply_UsesEnvValues_withDefault(t *testing.T) {
 	r := require.New(t)
 	r.NoError(fl.Apply(set))
 	r.NoError(set.Parse(nil))
+	r.NoError(fl.PostParse())
 	r.Equal([]uint64{3, 4}, val.Value())
 	r.Equal([]uint64{1, 2}, set.Lookup("goat").Value.(flag.Getter).Get().([]uint64))
 }
@@ -1209,6 +1219,7 @@ func TestUintSliceFlagApply_DefaultValueWithDestination(t *testing.T) {
 
 	err := set.Parse([]string{})
 	assert.NoError(t, err)
+	assert.NoError(t, fl.PostParse())
 	assert.Equal(t, defValue, dest)
 }
 
@@ -1328,6 +1339,7 @@ func TestUint64SliceFlagApply_UsesEnvValues_noDefault(t *testing.T) {
 
 	err := set.Parse(nil)
 	assert.NoError(t, err)
+	assert.NoError(t, fl.PostParse())
 	assert.Equal(t, []uint64{1, 2}, set.Lookup("goat").Value.(flag.Getter).Get().([]uint64))
 }
 
@@ -1341,6 +1353,7 @@ func TestUint64SliceFlagApply_UsesEnvValues_withDefault(t *testing.T) {
 	_ = fl.Apply(set)
 	err := set.Parse(nil)
 	assert.NoError(t, err)
+	assert.NoError(t, fl.PostParse())
 	assert.Equal(t, []uint64{1, 2}, set.Lookup("goat").Value.(flag.Getter).Get().([]uint64))
 }
 
@@ -1354,6 +1367,7 @@ func TestUint64SliceFlagApply_DefaultValueWithDestination(t *testing.T) {
 
 	err := set.Parse([]string{})
 	assert.NoError(t, err)
+	assert.NoError(t, fl.PostParse())
 	assert.Equal(t, defValue, dest)
 }
 
@@ -1519,6 +1533,7 @@ func TestFloat64SliceFlagApply_UsesEnvValues_noDefault(t *testing.T) {
 
 	err := set.Parse(nil)
 	assert.NoError(t, err)
+	assert.NoError(t, fl.PostParse())
 	assert.Equal(t, []float64{1, 2}, set.Lookup("goat").Value.(flag.Getter).Get().([]float64))
 }
 
@@ -1532,6 +1547,7 @@ func TestFloat64SliceFlagApply_UsesEnvValues_withDefault(t *testing.T) {
 	_ = fl.Apply(set)
 	err := set.Parse(nil)
 	assert.NoError(t, err)
+	assert.NoError(t, fl.PostParse())
 	assert.Equal(t, []float64{1, 2}, set.Lookup("goat").Value.(flag.Getter).Get().([]float64))
 }
 
@@ -3056,7 +3072,9 @@ func TestStringMapFlagApply_UsesEnvValues_noDefault(t *testing.T) {
 	_ = fl.Apply(set)
 
 	err := set.Parse(nil)
+
 	assert.NoError(t, err)
+	assert.NoError(t, fl.PostParse())
 	assert.Nil(t, val)
 	assert.Equal(t, map[string]string{"vincent van goat": "scape goat"}, set.Lookup("goat").Value.(flag.Getter).Get())
 }
@@ -3071,6 +3089,7 @@ func TestStringMapFlagApply_UsesEnvValues_withDefault(t *testing.T) {
 	_ = fl.Apply(set)
 	err := set.Parse(nil)
 	assert.NoError(t, err)
+	assert.NoError(t, fl.PostParse())
 	assert.Equal(t, map[string]string{`some default`: `values here`}, val)
 	assert.Equal(t, map[string]string{"vincent van goat": "scape goat"}, set.Lookup("goat").Value.(flag.Getter).Get())
 }

godoc-current.txt

@@ -285,6 +285,8 @@ func (parent *BoolWithInverseFlag) IsSet() bool
 
 func (parent *BoolWithInverseFlag) Names() []string
 
+func (parent *BoolWithInverseFlag) PostParse() error
+
 func (parent *BoolWithInverseFlag) RunAction(ctx context.Context, cmd *Command) error
 
 func (parent *BoolWithInverseFlag) String() string
@@ -625,6 +627,8 @@ type ExitErrHandlerFunc func(context.Context, *Command, error)
 type Flag interface {
 	fmt.Stringer
 
+	PostParse() error
+
 	// Apply Flag settings to the given flag set
 	Apply(*flag.FlagSet) error
 
@@ -734,6 +738,9 @@ func (f *FlagBase[T, C, V]) IsVisible() bool
 func (f *FlagBase[T, C, V]) Names() []string
     Names returns the names of the flag
 
+func (f *FlagBase[T, C, V]) PostParse() error
+    PostParse populates the flag given the flag set and environment
+
 func (f *FlagBase[T, C, V]) RunAction(ctx context.Context, cmd *Command) error
     RunAction executes flag action if set
 

testdata/godoc-v3.x.txt

@@ -285,6 +285,8 @@ func (parent *BoolWithInverseFlag) IsSet() bool
 
 func (parent *BoolWithInverseFlag) Names() []string
 
+func (parent *BoolWithInverseFlag) PostParse() error
+
 func (parent *BoolWithInverseFlag) RunAction(ctx context.Context, cmd *Command) error
 
 func (parent *BoolWithInverseFlag) String() string
@@ -625,6 +627,8 @@ type ExitErrHandlerFunc func(context.Context, *Command, error)
 type Flag interface {
 	fmt.Stringer
 
+	PostParse() error
+
 	// Apply Flag settings to the given flag set
 	Apply(*flag.FlagSet) error
 
@@ -734,6 +738,9 @@ func (f *FlagBase[T, C, V]) IsVisible() bool
 func (f *FlagBase[T, C, V]) Names() []string
     Names returns the names of the flag
 
+func (f *FlagBase[T, C, V]) PostParse() error
+    PostParse populates the flag given the flag set and environment
+
 func (f *FlagBase[T, C, V]) RunAction(ctx context.Context, cmd *Command) error
     RunAction executes flag action if set