flag: remove dependencies on shared variables

See #1670 for context
This commit creates a new type separatorSpec that will get passed into
flag parser, instead of reading from shared variables.

app.go

@@ -121,7 +121,8 @@ type App struct {
 	// Treat all flags as normal arguments if true
 	SkipFlagParsing bool
 
-	didSetup bool
+	didSetup  bool
+	separator separatorSpec
 
 	rootCommand *Command
 }
@@ -216,15 +217,25 @@ func (a *App) Setup() {
 		})
 	}
 
+	if len(a.SliceFlagSeparator) != 0 {
+		a.separator.customized = true
+		a.separator.sep = a.SliceFlagSeparator
+	}
+
+	if a.DisableSliceFlagSeparator {
+		a.separator.customized = true
+		a.separator.disabled = true
+	}
+
 	var newCommands []*Command
 
 	for _, c := range a.Commands {
 		cname := c.Name
 		if c.HelpName != "" {
 			cname = c.HelpName
 		}
+		c.separator = a.separator
 		c.HelpName = fmt.Sprintf("%s %s", a.HelpName, cname)
-
 		c.flagCategories = newFlagCategoriesFromFlags(c.Flags)
 		newCommands = append(newCommands, c)
 	}
@@ -262,12 +273,6 @@ func (a *App) Setup() {
 	if a.Metadata == nil {
 		a.Metadata = make(map[string]interface{})
 	}
-
-	if len(a.SliceFlagSeparator) != 0 {
-		defaultSliceFlagSeparator = a.SliceFlagSeparator
-	}
-
-	disableSliceFlagSeparator = a.DisableSliceFlagSeparator
 }
 
 func (a *App) newRootCommand() *Command {
@@ -293,11 +298,12 @@ func (a *App) newRootCommand() *Command {
 		categories:             a.categories,
 		SkipFlagParsing:        a.SkipFlagParsing,
 		isRoot:                 true,
+		separator:              a.separator,
 	}
 }
 
 func (a *App) newFlagSet() (*flag.FlagSet, error) {
-	return flagSet(a.Name, a.Flags)
+	return flagSet(a.Name, a.Flags, a.separator)
 }
 
 func (a *App) useShortOptionHandling() bool {

app_test.go

@@ -2532,7 +2532,7 @@ func TestCustomHelpVersionFlags(t *testing.T) {
 
 func TestHandleExitCoder_Default(t *testing.T) {
 	app := newTestApp()
-	fs, err := flagSet(app.Name, app.Flags)
+	fs, err := flagSet(app.Name, app.Flags, separatorSpec{})
 	if err != nil {
 		t.Errorf("error creating FlagSet: %s", err)
 	}
@@ -2548,7 +2548,7 @@ func TestHandleExitCoder_Default(t *testing.T) {
 
 func TestHandleExitCoder_Custom(t *testing.T) {
 	app := newTestApp()
-	fs, err := flagSet(app.Name, app.Flags)
+	fs, err := flagSet(app.Name, app.Flags, separatorSpec{})
 	if err != nil {
 		t.Errorf("error creating FlagSet: %s", err)
 	}

command.go

@@ -69,6 +69,8 @@ type Command struct {
 
 	// if this is a root "special" command
 	isRoot bool
+
+	separator separatorSpec
 }
 
 type Commands []*Command
@@ -275,7 +277,7 @@ func (c *Command) Run(cCtx *Context, arguments ...string) (err error) {
 }
 
 func (c *Command) newFlagSet() (*flag.FlagSet, error) {
-	return flagSet(c.Name, c.Flags)
+	return flagSet(c.Name, c.Flags, c.separator)
 }
 
 func (c *Command) useShortOptionHandling() bool {

flag-spec.yaml

@@ -20,6 +20,8 @@ flag_types:
     skip_interfaces:
       - fmt.Stringer
     struct_fields:
+      - name: separator
+        type: separatorSpec
       - name: Action
         type: "func(*Context, []float64) error"
   int:
@@ -33,6 +35,8 @@ flag_types:
     skip_interfaces:
       - fmt.Stringer
     struct_fields:
+      - name: separator
+        type: separatorSpec
       - name: Action
         type: "func(*Context, []int) error"
   int64:
@@ -46,6 +50,8 @@ flag_types:
     skip_interfaces:
       - fmt.Stringer
     struct_fields:
+      - name: separator
+        type: separatorSpec
       - name: Action
         type: "func(*Context, []int64) error"
   uint:
@@ -59,6 +65,8 @@ flag_types:
     skip_interfaces:
       - fmt.Stringer
     struct_fields:
+      - name: separator
+        type: separatorSpec
       - name: Action
         type: "func(*Context, []uint) error"
   uint64:
@@ -72,6 +80,8 @@ flag_types:
     skip_interfaces:
       - fmt.Stringer
     struct_fields:
+      - name: separator
+        type: separatorSpec
       - name: Action
         type: "func(*Context, []uint64) error"
   string:
@@ -85,6 +95,8 @@ flag_types:
     skip_interfaces:
       - fmt.Stringer
     struct_fields:
+      - name: separator
+        type: separatorSpec
       - name: TakesFile
         type: bool
       - name: Action

flag.go

@@ -15,7 +15,7 @@ import (
 
 const defaultPlaceholder = "value"
 
-var (
+const (
 	defaultSliceFlagSeparator = ","
 	disableSliceFlagSeparator = false
 )
@@ -167,10 +167,13 @@ type Countable interface {
 	Count() int
 }
 
-func flagSet(name string, flags []Flag) (*flag.FlagSet, error) {
+func flagSet(name string, flags []Flag, spec separatorSpec) (*flag.FlagSet, error) {
 	set := flag.NewFlagSet(name, flag.ContinueOnError)
 
 	for _, f := range flags {
+		if c, ok := f.(customizedSeparator); ok {
+			c.WithSeparatorSpec(spec)
+		}
 		if err := f.Apply(set); err != nil {
 			return nil, err
 		}
@@ -389,10 +392,28 @@ func flagFromEnvOrFile(envVars []string, filePath string) (value string, fromWhe
 	return "", "", false
 }
 
-func flagSplitMultiValues(val string) []string {
-	if disableSliceFlagSeparator {
+type customizedSeparator interface {
+	WithSeparatorSpec(separatorSpec)
+}
+
+type separatorSpec struct {
+	sep        string
+	disabled   bool
+	customized bool
+}
+
+func (s separatorSpec) flagSplitMultiValues(val string) []string {
+	var (
+		disabled bool   = s.disabled
+		sep      string = s.sep
+	)
+	if !s.customized {
+		disabled = disableSliceFlagSeparator
+		sep = defaultSliceFlagSeparator
+	}
+	if disabled {
 		return []string{val}
 	}
 
-	return strings.Split(val, defaultSliceFlagSeparator)
+	return strings.Split(val, sep)
 }

flag_float64_slice.go

@@ -11,6 +11,7 @@ import (
 // Float64Slice wraps []float64 to satisfy flag.Value
 type Float64Slice struct {
 	slice      []float64
+	separator  separatorSpec
 	hasBeenSet bool
 }
 
@@ -29,6 +30,10 @@ func (f *Float64Slice) clone() *Float64Slice {
 	return n
 }
 
+func (f *Float64Slice) WithSeparatorSpec(spec separatorSpec) {
+	f.separator = spec
+}
+
 // Set parses the value into a float64 and appends it to the list of values
 func (f *Float64Slice) Set(value string) error {
 	if !f.hasBeenSet {
@@ -43,7 +48,7 @@ func (f *Float64Slice) Set(value string) error {
 		return nil
 	}
 
-	for _, s := range flagSplitMultiValues(value) {
+	for _, s := range f.separator.flagSplitMultiValues(value) {
 		tmp, err := strconv.ParseFloat(strings.TrimSpace(s), 64)
 		if err != nil {
 			return err
@@ -148,11 +153,12 @@ func (f *Float64SliceFlag) Apply(set *flag.FlagSet) error {
 		setValue = f.Value.clone()
 	default:
 		setValue = new(Float64Slice)
+		setValue.WithSeparatorSpec(f.separator)
 	}
 
 	if val, source, found := flagFromEnvOrFile(f.EnvVars, f.FilePath); found {
 		if val != "" {
-			for _, s := range flagSplitMultiValues(val) {
+			for _, s := range f.separator.flagSplitMultiValues(val) {
 				if err := setValue.Set(strings.TrimSpace(s)); err != nil {
 					return fmt.Errorf("could not parse %q as float64 slice value from %s for flag %s: %s", val, source, f.Name, err)
 				}
@@ -172,6 +178,10 @@ func (f *Float64SliceFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+func (f *Float64SliceFlag) WithSeparatorSpec(spec separatorSpec) {
+	f.separator = spec
+}
+
 // Get returns the flag’s value in the given Context.
 func (f *Float64SliceFlag) Get(ctx *Context) []float64 {
 	return ctx.Float64Slice(f.Name)

flag_int64_slice.go

@@ -11,6 +11,7 @@ import (
 // Int64Slice wraps []int64 to satisfy flag.Value
 type Int64Slice struct {
 	slice      []int64
+	separator  separatorSpec
 	hasBeenSet bool
 }
 
@@ -29,6 +30,10 @@ func (i *Int64Slice) clone() *Int64Slice {
 	return n
 }
 
+func (i *Int64Slice) WithSeparatorSpec(spec separatorSpec) {
+	i.separator = spec
+}
+
 // Set parses the value into an integer and appends it to the list of values
 func (i *Int64Slice) Set(value string) error {
 	if !i.hasBeenSet {
@@ -43,7 +48,7 @@ func (i *Int64Slice) Set(value string) error {
 		return nil
 	}
 
-	for _, s := range flagSplitMultiValues(value) {
+	for _, s := range i.separator.flagSplitMultiValues(value) {
 		tmp, err := strconv.ParseInt(strings.TrimSpace(s), 0, 64)
 		if err != nil {
 			return err
@@ -149,10 +154,11 @@ func (f *Int64SliceFlag) Apply(set *flag.FlagSet) error {
 		setValue = f.Value.clone()
 	default:
 		setValue = new(Int64Slice)
+		setValue.WithSeparatorSpec(f.separator)
 	}
 
 	if val, source, ok := flagFromEnvOrFile(f.EnvVars, f.FilePath); ok && val != "" {
-		for _, s := range flagSplitMultiValues(val) {
+		for _, s := range f.separator.flagSplitMultiValues(val) {
 			if err := setValue.Set(strings.TrimSpace(s)); err != nil {
 				return fmt.Errorf("could not parse %q as int64 slice value from %s for flag %s: %s", val, source, f.Name, err)
 			}
@@ -171,6 +177,10 @@ func (f *Int64SliceFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+func (f *Int64SliceFlag) WithSeparatorSpec(spec separatorSpec) {
+	f.separator = spec
+}
+
 // Get returns the flag’s value in the given Context.
 func (f *Int64SliceFlag) Get(ctx *Context) []int64 {
 	return ctx.Int64Slice(f.Name)

flag_int_slice.go

@@ -11,6 +11,7 @@ import (
 // IntSlice wraps []int to satisfy flag.Value
 type IntSlice struct {
 	slice      []int
+	separator  separatorSpec
 	hasBeenSet bool
 }
 
@@ -40,6 +41,10 @@ func (i *IntSlice) SetInt(value int) {
 	i.slice = append(i.slice, value)
 }
 
+func (i *IntSlice) WithSeparatorSpec(spec separatorSpec) {
+	i.separator = spec
+}
+
 // Set parses the value into an integer and appends it to the list of values
 func (i *IntSlice) Set(value string) error {
 	if !i.hasBeenSet {
@@ -54,7 +59,7 @@ func (i *IntSlice) Set(value string) error {
 		return nil
 	}
 
-	for _, s := range flagSplitMultiValues(value) {
+	for _, s := range i.separator.flagSplitMultiValues(value) {
 		tmp, err := strconv.ParseInt(strings.TrimSpace(s), 0, 64)
 		if err != nil {
 			return err
@@ -160,10 +165,11 @@ func (f *IntSliceFlag) Apply(set *flag.FlagSet) error {
 		setValue = f.Value.clone()
 	default:
 		setValue = new(IntSlice)
+		setValue.WithSeparatorSpec(f.separator)
 	}
 
 	if val, source, ok := flagFromEnvOrFile(f.EnvVars, f.FilePath); ok && val != "" {
-		for _, s := range flagSplitMultiValues(val) {
+		for _, s := range f.separator.flagSplitMultiValues(val) {
 			if err := setValue.Set(strings.TrimSpace(s)); err != nil {
 				return fmt.Errorf("could not parse %q as int slice value from %s for flag %s: %s", val, source, f.Name, err)
 			}
@@ -182,6 +188,10 @@ func (f *IntSliceFlag) Apply(set *flag.FlagSet) error {
 	return nil
 }
 
+func (f *IntSliceFlag) WithSeparatorSpec(spec separatorSpec) {
+	f.separator = spec
+}
+
 // Get returns the flag’s value in the given Context.
 func (f *IntSliceFlag) Get(ctx *Context) []int {
 	return ctx.IntSlice(f.Name)