vendor: spf13/pflags v1.0.0

cmd/vendor/github.com/spf13/pflag/flag.go

@@ -16,9 +16,9 @@ pflag is a drop-in replacement of Go's native flag package. If you import
 pflag under the name "flag" then all code should continue to function
 with no changes.
 
-	import flag "github.com/ogier/pflag"
+	import flag "github.com/spf13/pflag"
 
-	There is one exception to this: if you directly instantiate the Flag struct
+There is one exception to this: if you directly instantiate the Flag struct
 there is one more field "Shorthand" that you will need to set.
 Most code never instantiates this struct directly, and instead uses
 functions such as String(), BoolVar(), and Var(), and is therefore
@@ -134,14 +134,21 @@ type FlagSet struct {
 	// a custom error handler.
 	Usage func()
 
+	// SortFlags is used to indicate, if user wants to have sorted flags in
+	// help/usage messages.
+	SortFlags bool
+
 	name              string
 	parsed            bool
 	actual            map[NormalizedName]*Flag
+	orderedActual     []*Flag
+	sortedActual      []*Flag
 	formal            map[NormalizedName]*Flag
+	orderedFormal     []*Flag
+	sortedFormal      []*Flag
 	shorthands        map[byte]*Flag
 	args              []string // arguments after flags
 	argsLenAtDash     int      // len(args) when a '--' was located when parsing, or -1 if no --
-	exitOnError       bool     // does the program exit if there's an error?
 	errorHandling     ErrorHandling
 	output            io.Writer // nil means stderr; use out() accessor
 	interspersed      bool      // allow interspersed option/non-option args
@@ -156,7 +163,7 @@ type Flag struct {
 	Value               Value               // value as set
 	DefValue            string              // default value (as text); for usage message
 	Changed             bool                // If the user set the value (or if left to default)
-	NoOptDefVal         string              //default value (as text); if the flag is on the command line without any options
+	NoOptDefVal         string              // default value (as text); if the flag is on the command line without any options
 	Deprecated          string              // If this flag is deprecated, this string is the new or now thing to use
 	Hidden              bool                // used by cobra.Command to allow flags to be hidden from help/usage text
 	ShorthandDeprecated string              // If the shorthand of this flag is deprecated, this string is the new or now thing to use
@@ -194,11 +201,13 @@ func sortFlags(flags map[NormalizedName]*Flag) []*Flag {
 // "--getUrl" which may also be translated to "geturl" and everything will work.
 func (f *FlagSet) SetNormalizeFunc(n func(f *FlagSet, name string) NormalizedName) {
 	f.normalizeNameFunc = n
-	for k, v := range f.formal {
-		delete(f.formal, k)
-		nname := f.normalizeFlagName(string(k))
-		f.formal[nname] = v
+	f.sortedFormal = f.sortedFormal[:0]
+	for k, v := range f.orderedFormal {
+		delete(f.formal, NormalizedName(v.Name))
+		nname := f.normalizeFlagName(v.Name)
 		v.Name = string(nname)
+		f.formal[nname] = v
+		f.orderedFormal[k] = v
 	}
 }
 
@@ -229,10 +238,25 @@ func (f *FlagSet) SetOutput(output io.Writer) {
 	f.output = output
 }
 
-// VisitAll visits the flags in lexicographical order, calling fn for each.
+// VisitAll visits the flags in lexicographical order or
+// in primordial order if f.SortFlags is false, calling fn for each.
 // It visits all flags, even those not set.
 func (f *FlagSet) VisitAll(fn func(*Flag)) {
-	for _, flag := range sortFlags(f.formal) {
+	if len(f.formal) == 0 {
+		return
+	}
+
+	var flags []*Flag
+	if f.SortFlags {
+		if len(f.formal) != len(f.sortedFormal) {
+			f.sortedFormal = sortFlags(f.formal)
+		}
+		flags = f.sortedFormal
+	} else {
+		flags = f.orderedFormal
+	}
+
+	for _, flag := range flags {
 		fn(flag)
 	}
 }
@@ -242,22 +266,50 @@ func (f *FlagSet) HasFlags() bool {
 	return len(f.formal) > 0
 }
 
-// VisitAll visits the command-line flags in lexicographical order, calling
-// fn for each.  It visits all flags, even those not set.
+// HasAvailableFlags returns a bool to indicate if the FlagSet has any flags
+// definied that are not hidden or deprecated.
+func (f *FlagSet) HasAvailableFlags() bool {
+	for _, flag := range f.formal {
+		if !flag.Hidden && len(flag.Deprecated) == 0 {
+			return true
+		}
+	}
+	return false
+}
+
+// VisitAll visits the command-line flags in lexicographical order or
+// in primordial order if f.SortFlags is false, calling fn for each.
+// It visits all flags, even those not set.
 func VisitAll(fn func(*Flag)) {
 	CommandLine.VisitAll(fn)
 }
 
-// Visit visits the flags in lexicographical order, calling fn for each.
+// Visit visits the flags in lexicographical order or
+// in primordial order if f.SortFlags is false, calling fn for each.
 // It visits only those flags that have been set.
 func (f *FlagSet) Visit(fn func(*Flag)) {
-	for _, flag := range sortFlags(f.actual) {
+	if len(f.actual) == 0 {
+		return
+	}
+
+	var flags []*Flag
+	if f.SortFlags {
+		if len(f.actual) != len(f.sortedActual) {
+			f.sortedActual = sortFlags(f.actual)
+		}
+		flags = f.sortedActual
+	} else {
+		flags = f.orderedActual
+	}
+
+	for _, flag := range flags {
 		fn(flag)
 	}
 }
 
-// Visit visits the command-line flags in lexicographical order, calling fn
-// for each.  It visits only those flags that have been set.
+// Visit visits the command-line flags in lexicographical order or
+// in primordial order if f.SortFlags is false, calling fn for each.
+// It visits only those flags that have been set.
 func Visit(fn func(*Flag)) {
 	CommandLine.Visit(fn)
 }
@@ -267,6 +319,22 @@ func (f *FlagSet) Lookup(name string) *Flag {
 	return f.lookup(f.normalizeFlagName(name))
 }
 
+// ShorthandLookup returns the Flag structure of the short handed flag,
+// returning nil if none exists.
+// It panics, if len(name) > 1.
+func (f *FlagSet) ShorthandLookup(name string) *Flag {
+	if name == "" {
+		return nil
+	}
+	if len(name) > 1 {
+		msg := fmt.Sprintf("can not look up shorthand which is more than one ASCII character: %q", name)
+		fmt.Fprintf(f.out(), msg)
+		panic(msg)
+	}
+	c := name[0]
+	return f.shorthands[c]
+}
+
 // lookup returns the Flag structure of the named flag, returning nil if none exists.
 func (f *FlagSet) lookup(name NormalizedName) *Flag {
 	return f.formal[name]
@@ -308,7 +376,7 @@ func (f *FlagSet) MarkDeprecated(name string, usageMessage string) error {
 	if flag == nil {
 		return fmt.Errorf("flag %q does not exist", name)
 	}
-	if len(usageMessage) == 0 {
+	if usageMessage == "" {
 		return fmt.Errorf("deprecated message for flag %q must be set", name)
 	}
 	flag.Deprecated = usageMessage
@@ -323,7 +391,7 @@ func (f *FlagSet) MarkShorthandDeprecated(name string, usageMessage string) erro
 	if flag == nil {
 		return fmt.Errorf("flag %q does not exist", name)
 	}
-	if len(usageMessage) == 0 {
+	if usageMessage == "" {
 		return fmt.Errorf("deprecated message for flag %q must be set", name)
 	}
 	flag.ShorthandDeprecated = usageMessage
@@ -347,6 +415,12 @@ func Lookup(name string) *Flag {
 	return CommandLine.Lookup(name)
 }
 
+// ShorthandLookup returns the Flag structure of the short handed flag,
+// returning nil if none exists.
+func ShorthandLookup(name string) *Flag {
+	return CommandLine.ShorthandLookup(name)
+}
+
 // Set sets the value of the named flag.
 func (f *FlagSet) Set(name, value string) error {
 	normalName := f.normalizeFlagName(name)
@@ -354,17 +428,28 @@ func (f *FlagSet) Set(name, value string) error {
 	if !ok {
 		return fmt.Errorf("no such flag -%v", name)
 	}
+
 	err := flag.Value.Set(value)
 	if err != nil {
-		return err
+		var flagName string
+		if flag.Shorthand != "" && flag.ShorthandDeprecated == "" {
+			flagName = fmt.Sprintf("-%s, --%s", flag.Shorthand, flag.Name)
+		} else {
+			flagName = fmt.Sprintf("--%s", flag.Name)
+		}
+		return fmt.Errorf("invalid argument %q for %q flag: %v", value, flagName, err)
 	}
+
 	if f.actual == nil {
 		f.actual = make(map[NormalizedName]*Flag)
 	}
 	f.actual[normalName] = flag
+	f.orderedActual = append(f.orderedActual, flag)
+
 	flag.Changed = true
-	if len(flag.Deprecated) > 0 {
-		fmt.Fprintf(os.Stderr, "Flag --%s has been deprecated, %s\n", flag.Name, flag.Deprecated)
+
+	if flag.Deprecated != "" {
+		fmt.Fprintf(f.out(), "Flag --%s has been deprecated, %s\n", flag.Name, flag.Deprecated)
 	}
 	return nil
 }
@@ -405,45 +490,214 @@ func Set(name, value string) error {
 // otherwise, the default values of all defined flags in the set.
 func (f *FlagSet) PrintDefaults() {
 	usages := f.FlagUsages()
-	fmt.Fprintf(f.out(), "%s", usages)
+	fmt.Fprint(f.out(), usages)
 }
 
-// FlagUsages Returns a string containing the usage information for all flags in
-// the FlagSet
-func (f *FlagSet) FlagUsages() string {
-	x := new(bytes.Buffer)
+// defaultIsZeroValue returns true if the default value for this flag represents
+// a zero value.
+func (f *Flag) defaultIsZeroValue() bool {
+	switch f.Value.(type) {
+	case boolFlag:
+		return f.DefValue == "false"
+	case *durationValue:
+		// Beginning in Go 1.7, duration zero values are "0s"
+		return f.DefValue == "0" || f.DefValue == "0s"
+	case *intValue, *int8Value, *int32Value, *int64Value, *uintValue, *uint8Value, *uint16Value, *uint32Value, *uint64Value, *countValue, *float32Value, *float64Value:
+		return f.DefValue == "0"
+	case *stringValue:
+		return f.DefValue == ""
+	case *ipValue, *ipMaskValue, *ipNetValue:
+		return f.DefValue == "<nil>"
+	case *intSliceValue, *stringSliceValue, *stringArrayValue:
+		return f.DefValue == "[]"
+	default:
+		switch f.Value.String() {
+		case "false":
+			return true
+		case "<nil>":
+			return true
+		case "":
+			return true
+		case "0":
+			return true
+		}
+		return false
+	}
+}
 
+// UnquoteUsage extracts a back-quoted name from the usage
+// string for a flag and returns it and the un-quoted usage.
+// Given "a `name` to show" it returns ("name", "a name to show").
+// If there are no back quotes, the name is an educated guess of the
+// type of the flag's value, or the empty string if the flag is boolean.
+func UnquoteUsage(flag *Flag) (name string, usage string) {
+	// Look for a back-quoted name, but avoid the strings package.
+	usage = flag.Usage
+	for i := 0; i < len(usage); i++ {
+		if usage[i] == '`' {
+			for j := i + 1; j < len(usage); j++ {
+				if usage[j] == '`' {
+					name = usage[i+1 : j]
+					usage = usage[:i] + name + usage[j+1:]
+					return name, usage
+				}
+			}
+			break // Only one back quote; use type name.
+		}
+	}
+
+	name = flag.Value.Type()
+	switch name {
+	case "bool":
+		name = ""
+	case "float64":
+		name = "float"
+	case "int64":
+		name = "int"
+	case "uint64":
+		name = "uint"
+	}
+
+	return
+}
+
+// Splits the string `s` on whitespace into an initial substring up to
+// `i` runes in length and the remainder. Will go `slop` over `i` if
+// that encompasses the entire string (which allows the caller to
+// avoid short orphan words on the final line).
+func wrapN(i, slop int, s string) (string, string) {
+	if i+slop > len(s) {
+		return s, ""
+	}
+
+	w := strings.LastIndexAny(s[:i], " \t")
+	if w <= 0 {
+		return s, ""
+	}
+
+	return s[:w], s[w+1:]
+}
+
+// Wraps the string `s` to a maximum width `w` with leading indent
+// `i`. The first line is not indented (this is assumed to be done by
+// caller). Pass `w` == 0 to do no wrapping
+func wrap(i, w int, s string) string {
+	if w == 0 {
+		return s
+	}
+
+	// space between indent i and end of line width w into which
+	// we should wrap the text.
+	wrap := w - i
+
+	var r, l string
+
+	// Not enough space for sensible wrapping. Wrap as a block on
+	// the next line instead.
+	if wrap < 24 {
+		i = 16
+		wrap = w - i
+		r += "\n" + strings.Repeat(" ", i)
+	}
+	// If still not enough space then don't even try to wrap.
+	if wrap < 24 {
+		return s
+	}
+
+	// Try to avoid short orphan words on the final line, by
+	// allowing wrapN to go a bit over if that would fit in the
+	// remainder of the line.
+	slop := 5
+	wrap = wrap - slop
+
+	// Handle first line, which is indented by the caller (or the
+	// special case above)
+	l, s = wrapN(wrap, slop, s)
+	r = r + l
+
+	// Now wrap the rest
+	for s != "" {
+		var t string
+
+		t, s = wrapN(wrap, slop, s)
+		r = r + "\n" + strings.Repeat(" ", i) + t
+	}
+
+	return r
+
+}
+
+// FlagUsagesWrapped returns a string containing the usage information
+// for all flags in the FlagSet. Wrapped to `cols` columns (0 for no
+// wrapping)
+func (f *FlagSet) FlagUsagesWrapped(cols int) string {
+	buf := new(bytes.Buffer)
+
+	lines := make([]string, 0, len(f.formal))
+
+	maxlen := 0
 	f.VisitAll(func(flag *Flag) {
-		if len(flag.Deprecated) > 0 || flag.Hidden {
+		if flag.Deprecated != "" || flag.Hidden {
 			return
 		}
-		format := ""
-		if len(flag.Shorthand) > 0 && len(flag.ShorthandDeprecated) == 0 {
-			format = "  -%s, --%s"
+
+		line := ""
+		if flag.Shorthand != "" && flag.ShorthandDeprecated == "" {
+			line = fmt.Sprintf("  -%s, --%s", flag.Shorthand, flag.Name)
 		} else {
-			format = "   %s   --%s"
+			line = fmt.Sprintf("      --%s", flag.Name)
 		}
-		if len(flag.NoOptDefVal) > 0 {
-			format = format + "["
+
+		varname, usage := UnquoteUsage(flag)
+		if varname != "" {
+			line += " " + varname
 		}
-		if flag.Value.Type() == "string" {
-			// put quotes on the value
-			format = format + "=%q"
-		} else {
-			format = format + "=%s"
+		if flag.NoOptDefVal != "" {
+			switch flag.Value.Type() {
+			case "string":
+				line += fmt.Sprintf("[=\"%s\"]", flag.NoOptDefVal)
+			case "bool":
+				if flag.NoOptDefVal != "true" {
+					line += fmt.Sprintf("[=%s]", flag.NoOptDefVal)
+				}
+			default:
+				line += fmt.Sprintf("[=%s]", flag.NoOptDefVal)
+			}
 		}
-		if len(flag.NoOptDefVal) > 0 {
-			format = format + "]"
+
+		// This special character will be replaced with spacing once the
+		// correct alignment is calculated
+		line += "\x00"
+		if len(line) > maxlen {
+			maxlen = len(line)
 		}
-		format = format + ": %s\n"
-		shorthand := flag.Shorthand
-		if len(flag.ShorthandDeprecated) > 0 {
-			shorthand = ""
+
+		line += usage
+		if !flag.defaultIsZeroValue() {
+			if flag.Value.Type() == "string" {
+				line += fmt.Sprintf(" (default %q)", flag.DefValue)
+			} else {
+				line += fmt.Sprintf(" (default %s)", flag.DefValue)
+			}
 		}
-		fmt.Fprintf(x, format, shorthand, flag.Name, flag.DefValue, flag.Usage)
+
+		lines = append(lines, line)
 	})
 
-	return x.String()
+	for _, line := range lines {
+		sidx := strings.Index(line, "\x00")
+		spacing := strings.Repeat(" ", maxlen-sidx)
+		// maxlen + 2 comes from + 1 for the \x00 and + 1 for the (deliberate) off-by-one in maxlen-sidx
+		fmt.Fprintln(buf, line[:sidx], spacing, wrap(maxlen+2, cols, line[sidx+1:]))
+	}
+
+	return buf.String()
+}
+
+// FlagUsages returns a string containing the usage information for all flags in
+// the FlagSet
+func (f *FlagSet) FlagUsages() string {
+	return f.FlagUsagesWrapped(0)
 }
 
 // PrintDefaults prints to standard error the default values of all defined command-line flags.
@@ -463,6 +717,8 @@ func defaultUsage(f *FlagSet) {
 
 // Usage prints to standard error a usage message documenting all defined command-line flags.
 // The function is a variable that may be changed to point to a custom function.
+// By default it prints a simple header and calls PrintDefaults; for details about the
+// format of the output and how to control it, see the documentation for PrintDefaults.
 var Usage = func() {
 	fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
 	PrintDefaults()
@@ -527,16 +783,15 @@ func (f *FlagSet) VarPF(value Value, name, shorthand, usage string) *Flag {
 
 // VarP is like Var, but accepts a shorthand letter that can be used after a single dash.
 func (f *FlagSet) VarP(value Value, name, shorthand, usage string) {
-	_ = f.VarPF(value, name, shorthand, usage)
+	f.VarPF(value, name, shorthand, usage)
 }
 
 // AddFlag will add the flag to the FlagSet
 func (f *FlagSet) AddFlag(flag *Flag) {
-	// Call normalizeFlagName function only once
 	normalizedFlagName := f.normalizeFlagName(flag.Name)
 
-	_, alreadythere := f.formal[normalizedFlagName]
-	if alreadythere {
+	_, alreadyThere := f.formal[normalizedFlagName]
+	if alreadyThere {
 		msg := fmt.Sprintf("%s flag redefined: %s", f.name, flag.Name)
 		fmt.Fprintln(f.out(), msg)
 		panic(msg) // Happens only if flags are declared with identical names
@@ -547,28 +802,31 @@ func (f *FlagSet) AddFlag(flag *Flag) {
 
 	flag.Name = string(normalizedFlagName)
 	f.formal[normalizedFlagName] = flag
+	f.orderedFormal = append(f.orderedFormal, flag)
 
-	if len(flag.Shorthand) == 0 {
+	if flag.Shorthand == "" {
 		return
 	}
 	if len(flag.Shorthand) > 1 {
-		fmt.Fprintf(f.out(), "%s shorthand more than ASCII character: %s\n", f.name, flag.Shorthand)
-		panic("shorthand is more than one character")
+		msg := fmt.Sprintf("%q shorthand is more than one ASCII character", flag.Shorthand)
+		fmt.Fprintf(f.out(), msg)
+		panic(msg)
 	}
 	if f.shorthands == nil {
 		f.shorthands = make(map[byte]*Flag)
 	}
 	c := flag.Shorthand[0]
-	old, alreadythere := f.shorthands[c]
-	if alreadythere {
-		fmt.Fprintf(f.out(), "%s shorthand reused: %q for %s already used for %s\n", f.name, c, flag.Name, old.Name)
-		panic("shorthand redefinition")
+	used, alreadyThere := f.shorthands[c]
+	if alreadyThere {
+		msg := fmt.Sprintf("unable to redefine %q shorthand in %q flagset: it's already used for %q flag", c, f.name, used.Name)
+		fmt.Fprintf(f.out(), msg)
+		panic(msg)
 	}
 	f.shorthands[c] = flag
 }
 
 // AddFlagSet adds one FlagSet to another. If a flag is already present in f
-// the flag from newSet will be ignored
+// the flag from newSet will be ignored.
 func (f *FlagSet) AddFlagSet(newSet *FlagSet) {
 	if newSet == nil {
 		return
@@ -616,45 +874,18 @@ func (f *FlagSet) usage() {
 	}
 }
 
-func (f *FlagSet) setFlag(flag *Flag, value string, origArg string) error {
-	if err := flag.Value.Set(value); err != nil {
-		return f.failf("invalid argument %q for %s: %v", value, origArg, err)
-	}
-	// mark as visited for Visit()
-	if f.actual == nil {
-		f.actual = make(map[NormalizedName]*Flag)
-	}
-	f.actual[f.normalizeFlagName(flag.Name)] = flag
-	flag.Changed = true
-	if len(flag.Deprecated) > 0 {
-		fmt.Fprintf(os.Stderr, "Flag --%s has been deprecated, %s\n", flag.Name, flag.Deprecated)
-	}
-	if len(flag.ShorthandDeprecated) > 0 && containsShorthand(origArg, flag.Shorthand) {
-		fmt.Fprintf(os.Stderr, "Flag shorthand -%s has been deprecated, %s\n", flag.Shorthand, flag.ShorthandDeprecated)
-	}
-	return nil
-}
-
-func containsShorthand(arg, shorthand string) bool {
-	// filter out flags --<flag_name>
-	if strings.HasPrefix(arg, "-") {
-		return false
-	}
-	arg = strings.SplitN(arg, "=", 2)[0]
-	return strings.Contains(arg, shorthand)
-}
-
-func (f *FlagSet) parseLongArg(s string, args []string) (a []string, err error) {
+func (f *FlagSet) parseLongArg(s string, args []string, fn parseFunc) (a []string, err error) {
 	a = args
 	name := s[2:]
 	if len(name) == 0 || name[0] == '-' || name[0] == '=' {
 		err = f.failf("bad flag syntax: %s", s)
 		return
 	}
+
 	split := strings.SplitN(name, "=", 2)
 	name = split[0]
-	flag, alreadythere := f.formal[f.normalizeFlagName(name)]
-	if !alreadythere {
+	flag, exists := f.formal[f.normalizeFlagName(name)]
+	if !exists {
 		if name == "help" { // special case for nice help message.
 			f.usage()
 			return a, ErrHelp
@@ -662,11 +893,12 @@ func (f *FlagSet) parseLongArg(s string, args []string) (a []string, err error)
 		err = f.failf("unknown flag: --%s", name)
 		return
 	}
+
 	var value string
 	if len(split) == 2 {
 		// '--flag=arg'
 		value = split[1]
-	} else if len(flag.NoOptDefVal) > 0 {
+	} else if flag.NoOptDefVal != "" {
 		// '--flag' (arg was optional)
 		value = flag.NoOptDefVal
 	} else if len(a) > 0 {
@@ -678,52 +910,68 @@ func (f *FlagSet) parseLongArg(s string, args []string) (a []string, err error)
 		err = f.failf("flag needs an argument: %s", s)
 		return
 	}
-	err = f.setFlag(flag, value, s)
+
+	err = fn(flag, value)
 	return
 }
 
-func (f *FlagSet) parseSingleShortArg(shorthands string, args []string) (outShorts string, outArgs []string, err error) {
+func (f *FlagSet) parseSingleShortArg(shorthands string, args []string, fn parseFunc) (outShorts string, outArgs []string, err error) {
+	if strings.HasPrefix(shorthands, "test.") {
+		return
+	}
+
 	outArgs = args
 	outShorts = shorthands[1:]
 	c := shorthands[0]
 
-	flag, alreadythere := f.shorthands[c]
-	if !alreadythere {
+	flag, exists := f.shorthands[c]
+	if !exists {
 		if c == 'h' { // special case for nice help message.
 			f.usage()
 			err = ErrHelp
 			return
 		}
-		//TODO continue on error
 		err = f.failf("unknown shorthand flag: %q in -%s", c, shorthands)
 		return
 	}
+
 	var value string
 	if len(shorthands) > 2 && shorthands[1] == '=' {
+		// '-f=arg'
 		value = shorthands[2:]
 		outShorts = ""
-	} else if len(flag.NoOptDefVal) > 0 {
+	} else if flag.NoOptDefVal != "" {
+		// '-f' (arg was optional)
 		value = flag.NoOptDefVal
 	} else if len(shorthands) > 1 {
+		// '-farg'
 		value = shorthands[1:]
 		outShorts = ""
 	} else if len(args) > 0 {
+		// '-f arg'
 		value = args[0]
 		outArgs = args[1:]
 	} else {
+		// '-f' (arg was required)
 		err = f.failf("flag needs an argument: %q in -%s", c, shorthands)
 		return
 	}
-	err = f.setFlag(flag, value, shorthands)
+
+	if flag.ShorthandDeprecated != "" {
+		fmt.Fprintf(f.out(), "Flag shorthand -%s has been deprecated, %s\n", flag.Shorthand, flag.ShorthandDeprecated)
+	}
+
+	err = fn(flag, value)
 	return
 }
 
-func (f *FlagSet) parseShortArg(s string, args []string) (a []string, err error) {
+func (f *FlagSet) parseShortArg(s string, args []string, fn parseFunc) (a []string, err error) {
 	a = args
 	shorthands := s[1:]
 
+	// "shorthands" can be a series of shorthand letters of flags (e.g. "-vvv").
 	for len(shorthands) > 0 {
-		shorthands, a, err = f.parseSingleShortArg(shorthands, args)
+		shorthands, a, err = f.parseSingleShortArg(shorthands, args, fn)
 		if err != nil {
 			return
 		}
@@ -732,7 +980,7 @@ func (f *FlagSet) parseShortArg(s string, args []string) (a []string, err error)
 	return
 }
 
-func (f *FlagSet) parseArgs(args []string) (err error) {
+func (f *FlagSet) parseArgs(args []string, fn parseFunc) (err error) {
 	for len(args) > 0 {
 		s := args[0]
 		args = args[1:]
@@ -752,9 +1000,9 @@ func (f *FlagSet) parseArgs(args []string) (err error) {
 				f.args = append(f.args, args...)
 				break
 			}
-			args, err = f.parseLongArg(s, args)
+			args, err = f.parseLongArg(s, args, fn)
 		} else {
-			args, err = f.parseShortArg(s, args)
+			args, err = f.parseShortArg(s, args, fn)
 		}
 		if err != nil {
 			return
@@ -769,8 +1017,43 @@ func (f *FlagSet) parseArgs(args []string) (err error) {
 // The return value will be ErrHelp if -help was set but not defined.
 func (f *FlagSet) Parse(arguments []string) error {
 	f.parsed = true
+
+	if len(arguments) < 0 {
+		return nil
+	}
+
 	f.args = make([]string, 0, len(arguments))
-	err := f.parseArgs(arguments)
+
+	set := func(flag *Flag, value string) error {
+		return f.Set(flag.Name, value)
+	}
+
+	err := f.parseArgs(arguments, set)
+	if err != nil {
+		switch f.errorHandling {
+		case ContinueOnError:
+			return err
+		case ExitOnError:
+			os.Exit(2)
+		case PanicOnError:
+			panic(err)
+		}
+	}
+	return nil
+}
+
+type parseFunc func(flag *Flag, value string) error
+
+// ParseAll parses flag definitions from the argument list, which should not
+// include the command name. The arguments for fn are flag and value. Must be
+// called after all flags in the FlagSet are defined and before flags are
+// accessed by the program. The return value will be ErrHelp if -help was set
+// but not defined.
+func (f *FlagSet) ParseAll(arguments []string, fn func(flag *Flag, value string) error) error {
+	f.parsed = true
+	f.args = make([]string, 0, len(arguments))
+
+	err := f.parseArgs(arguments, fn)
 	if err != nil {
 		switch f.errorHandling {
 		case ContinueOnError:
@@ -796,6 +1079,14 @@ func Parse() {
 	CommandLine.Parse(os.Args[1:])
 }
 
+// ParseAll parses the command-line flags from os.Args[1:] and called fn for each.
+// The arguments for fn are flag and value. Must be called after all flags are
+// defined and before flags are accessed by the program.
+func ParseAll(fn func(flag *Flag, value string) error) {
+	// Ignore errors; CommandLine is set for ExitOnError.
+	CommandLine.ParseAll(os.Args[1:], fn)
+}
+
 // SetInterspersed sets whether to support interspersed option/non-option arguments.
 func SetInterspersed(interspersed bool) {
 	CommandLine.SetInterspersed(interspersed)
@@ -806,17 +1097,18 @@ func Parsed() bool {
 	return CommandLine.Parsed()
 }
 
-// The default set of command-line flags, parsed from os.Args.
+// CommandLine is the default set of command-line flags, parsed from os.Args.
 var CommandLine = NewFlagSet(os.Args[0], ExitOnError)
 
-// NewFlagSet returns a new, empty flag set with the specified name and
-// error handling property.
+// NewFlagSet returns a new, empty flag set with the specified name,
+// error handling property and SortFlags set to true.
 func NewFlagSet(name string, errorHandling ErrorHandling) *FlagSet {
 	f := &FlagSet{
 		name:          name,
 		errorHandling: errorHandling,
 		argsLenAtDash: -1,
 		interspersed:  true,
+		SortFlags:     true,
 	}
 	return f
 }