mirror of
https://github.com/golang/go
synced 2024-11-26 00:57:56 -07:00
flag: document
also write to stderr not stdout R=rsc DELTA=48 (38 added, 2 deleted, 8 changed) OCL=25729 CL=25733
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d1ac21849e
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@ -96,7 +96,7 @@ test: test.files
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bignum.6: fmt.dirinstall
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bufio.6: io.dirinstall os.dirinstall
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exec.6: os.dirinstall
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flag.6: fmt.dirinstall
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flag.6: fmt.dirinstall os.dirinstall strconv.dirinstall
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log.6: fmt.dirinstall io.dirinstall os.dirinstall time.dirinstall
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once.6: sync.dirinstall
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strings.6: utf8.install
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@ -2,8 +2,6 @@
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package flag
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/*
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* Flags
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*
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@ -41,9 +39,11 @@ package flag
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* Integer flags accept 1234, 0664, 0x1234 and may be negative.
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* Boolean flags may be 1, 0, t, f, true, false, TRUE, FALSE, True, False.
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*/
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package flag
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import (
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"fmt";
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"os";
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"strconv"
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)
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@ -186,13 +186,14 @@ func (s *stringValue) String() string {
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return fmt.Sprintf("%s", *s.p)
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}
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// -- FlagValue interface
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// FlagValue is the interface to the dynamic value stored in a flag.
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// (The default value is represented as a string.)
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type FlagValue interface {
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String() string;
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set(string) bool;
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}
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// -- Flag structure
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// A Flag represents the state of a flag.
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type Flag struct {
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Name string; // name as it appears on command line
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Usage string; // help message
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@ -208,20 +209,21 @@ type allFlags struct {
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var flags *allFlags = &allFlags{make(map[string] *Flag), make(map[string] *Flag), 1}
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// Visit all flags, including those defined but not set.
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// VisitAll visits the flags, calling fn for each. It visits all flags, even those not set.
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func VisitAll(fn func(*Flag)) {
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for k, f := range flags.formal {
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fn(f)
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}
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}
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// Visit only those flags that have been set
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// Visit visits the flags, calling fn for each. It visits only those flags that have been set.
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func Visit(fn func(*Flag)) {
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for k, f := range flags.actual {
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fn(f)
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}
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}
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// Lookup returns the Flag structure of the named flag, returning nil if none exists.
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func Lookup(name string) *Flag {
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f, ok := flags.formal[name];
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if !ok {
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@ -230,6 +232,8 @@ func Lookup(name string) *Flag {
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return f
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}
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// Set sets the value of tne named flag. It returns true if the set succeeded; false if
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// there is no such flag defined.
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func Set(name, value string) bool {
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f, ok := flags.formal[name];
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if !ok {
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@ -243,6 +247,7 @@ func Set(name, value string) bool {
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return true;
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}
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// PrintDefaults prints to standard error the default values of all defined flags.
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func PrintDefaults() {
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VisitAll(func(f *Flag) {
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format := " -%s=%s: %s\n";
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@ -250,15 +255,17 @@ func PrintDefaults() {
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// put quotes on the value
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format = " -%s=%q: %s\n";
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}
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fmt.Printf(format, f.Name, f.DefValue, f.Usage);
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fmt.Fprintf(os.Stderr, format, f.Name, f.DefValue, f.Usage);
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})
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}
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// Usage prints to standard error a default usage message documenting all defined flags and
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// then calls sys.Exit(1).
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func Usage() {
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if len(sys.Args) > 0 {
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print("Usage of ", sys.Args[0], ": \n");
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fmt.Fprintf(os.Stderr, "Usage of ", sys.Args[0], ": \n");
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} else {
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print("Usage: \n");
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fmt.Fprintf(os.Stderr, "Usage: \n");
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}
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PrintDefaults();
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sys.Exit(1);
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@ -268,6 +275,8 @@ func NFlag() int {
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return len(flags.actual)
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}
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// Arg returns the i'th command-line argument. Arg(0) is the first remaining argument
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// after flags have been processed.
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func Arg(i int) string {
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i += flags.first_arg;
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if i < 0 || i >= len(sys.Args) {
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@ -276,6 +285,7 @@ func Arg(i int) string {
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return sys.Args[i]
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}
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// NArg is the number of arguments remaining after flags have been processed.
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func NArg() int {
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return len(sys.Args) - flags.first_arg
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}
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@ -291,60 +301,84 @@ func add(name string, value FlagValue, usage string) {
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flags.formal[name] = f;
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}
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// BoolVar defines a bool flag with specified name, default value, and usage string.
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// The argument p points to a bool variable in which to store the value of the flag.
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func BoolVar(p *bool, name string, value bool, usage string) {
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add(name, newBoolValue(value, p), usage);
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}
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// Bool defines a bool flag with specified name, default value, and usage string.
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// The return value is the address of a bool variable that stores the value of the flag.
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func Bool(name string, value bool, usage string) *bool {
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p := new(bool);
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BoolVar(p, name, value, usage);
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return p;
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}
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// IntVar defines an int flag with specified name, default value, and usage string.
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// The argument p points to an int variable in which to store the value of the flag.
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func IntVar(p *int, name string, value int, usage string) {
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add(name, newIntValue(value, p), usage);
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}
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// Int defines an int flag with specified name, default value, and usage string.
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// The return value is the address of an int variable that stores the value of the flag.
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func Int(name string, value int, usage string) *int {
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p := new(int);
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IntVar(p, name, value, usage);
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return p;
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}
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// Int64Var defines an int64 flag with specified name, default value, and usage string.
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// The argument p points to an int64 variable in which to store the value of the flag.
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func Int64Var(p *int64, name string, value int64, usage string) {
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add(name, newInt64Value(value, p), usage);
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}
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// Int64 defines an int64 flag with specified name, default value, and usage string.
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// The return value is the address of an int64 variable that stores the value of the flag.
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func Int64(name string, value int64, usage string) *int64 {
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p := new(int64);
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Int64Var(p, name, value, usage);
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return p;
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}
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// UintVar defines a uint flag with specified name, default value, and usage string.
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// The argument p points to a uint variable in which to store the value of the flag.
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func UintVar(p *uint, name string, value uint, usage string) {
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add(name, newUintValue(value, p), usage);
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}
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// Uint defines a uint flag with specified name, default value, and usage string.
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// The return value is the address of a uint variable that stores the value of the flag.
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func Uint(name string, value uint, usage string) *uint {
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p := new(uint);
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UintVar(p, name, value, usage);
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return p;
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}
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// Uint64Var defines a uint64 flag with specified name, default value, and usage string.
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// The argument p points to a uint64 variable in which to store the value of the flag.
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func Uint64Var(p *uint64, name string, value uint64, usage string) {
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add(name, newUint64Value(value, p), usage);
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}
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// Uint64 defines a uint64 flag with specified name, default value, and usage string.
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// The return value is the address of a uint64 variable that stores the value of the flag.
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func Uint64(name string, value uint64, usage string) *uint64 {
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p := new(uint64);
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Uint64Var(p, name, value, usage);
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return p;
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}
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// StringVar defines a string flag with specified name, default value, and usage string.
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// The argument p points to a string variable in which to store the value of the flag.
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func StringVar(p *string, name, value string, usage string) {
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add(name, newStringValue(value, p), usage);
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}
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// String defines a string flag with specified name, default value, and usage string.
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// The return value is the address of a string variable that stores the value of the flag.
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func String(name, value string, usage string) *string {
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p := new(string);
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StringVar(p, name, value, usage);
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@ -430,6 +464,8 @@ func (f *allFlags) parseOne(index int) (ok bool, next int)
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return true, index + 1
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}
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// Parse parses the command-line flags. Must be called after all flags are defined
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// and before any are accessed by the program.
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func Parse() {
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for i := 1; i < len(sys.Args); {
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ok, next := flags.parseOne(i);
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