diff --git a/flag.go b/flag.go index 24a5036e..7c058de3 100644 --- a/flag.go +++ b/flag.go @@ -160,7 +160,7 @@ type FlagSet struct { args []string // arguments after flags argsLenAtDash int // len(args) when a '--' was located when parsing, or -1 if no -- errorHandling ErrorHandling - output io.Writer // nil means stderr; use out() accessor + output io.Writer // nil means stderr; use Output() accessor interspersed bool // allow interspersed option/non-option args normalizeNameFunc func(f *FlagSet, name string) NormalizedName @@ -255,13 +255,20 @@ func (f *FlagSet) normalizeFlagName(name string) NormalizedName { return n(f, name) } -func (f *FlagSet) out() io.Writer { +// Output returns the destination for usage and error messages. os.Stderr is returned if +// output was not set or was set to nil. +func (f *FlagSet) Output() io.Writer { if f.output == nil { return os.Stderr } return f.output } +// Name returns the name of the flag set. +func (f *FlagSet) Name() string { + return f.name +} + // SetOutput sets the destination for usage and error messages. // If output is nil, os.Stderr is used. func (f *FlagSet) SetOutput(output io.Writer) { @@ -358,7 +365,7 @@ func (f *FlagSet) ShorthandLookup(name string) *Flag { } 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) + fmt.Fprintf(f.Output(), msg) panic(msg) } c := name[0] @@ -482,7 +489,7 @@ func (f *FlagSet) Set(name, value string) error { } if flag.Deprecated != "" { - fmt.Fprintf(f.out(), "Flag --%s has been deprecated, %s\n", flag.Name, flag.Deprecated) + fmt.Fprintf(f.Output(), "Flag --%s has been deprecated, %s\n", flag.Name, flag.Deprecated) } return nil } @@ -523,7 +530,7 @@ 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.Fprint(f.out(), usages) + fmt.Fprint(f.Output(), usages) } // defaultIsZeroValue returns true if the default value for this flag represents @@ -758,7 +765,7 @@ func PrintDefaults() { // defaultUsage is the default function to print a usage message. func defaultUsage(f *FlagSet) { - fmt.Fprintf(f.out(), "Usage of %s:\n", f.name) + fmt.Fprintf(f.Output(), "Usage of %s:\n", f.name) f.PrintDefaults() } @@ -844,7 +851,7 @@ func (f *FlagSet) AddFlag(flag *Flag) { _, alreadyThere := f.formal[normalizedFlagName] if alreadyThere { msg := fmt.Sprintf("%s flag redefined: %s", f.name, flag.Name) - fmt.Fprintln(f.out(), msg) + fmt.Fprintln(f.Output(), msg) panic(msg) // Happens only if flags are declared with identical names } if f.formal == nil { @@ -860,7 +867,7 @@ func (f *FlagSet) AddFlag(flag *Flag) { } if len(flag.Shorthand) > 1 { msg := fmt.Sprintf("%q shorthand is more than one ASCII character", flag.Shorthand) - fmt.Fprintf(f.out(), msg) + fmt.Fprintf(f.Output(), msg) panic(msg) } if f.shorthands == nil { @@ -870,7 +877,7 @@ func (f *FlagSet) AddFlag(flag *Flag) { 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) + fmt.Fprintf(f.Output(), msg) panic(msg) } f.shorthands[c] = flag @@ -909,7 +916,7 @@ func VarP(value Value, name, shorthand, usage string) { func (f *FlagSet) failf(format string, a ...interface{}) error { err := fmt.Errorf(format, a...) if f.errorHandling != ContinueOnError { - fmt.Fprintln(f.out(), err) + fmt.Fprintln(f.Output(), err) f.usage() } return err @@ -1060,7 +1067,7 @@ func (f *FlagSet) parseSingleShortArg(shorthands string, args []string, fn parse } if flag.ShorthandDeprecated != "" { - fmt.Fprintf(f.out(), "Flag shorthand -%s has been deprecated, %s\n", flag.Shorthand, flag.ShorthandDeprecated) + fmt.Fprintf(f.Output(), "Flag shorthand -%s has been deprecated, %s\n", flag.Shorthand, flag.ShorthandDeprecated) } err = fn(flag, value) diff --git a/flag_test.go b/flag_test.go index 7d02dbc8..58a5d25a 100644 --- a/flag_test.go +++ b/flag_test.go @@ -159,6 +159,16 @@ func TestAnnotation(t *testing.T) { } } +func TestName(t *testing.T) { + flagSetName := "bob" + f := NewFlagSet(flagSetName, ContinueOnError) + + givenName := f.Name() + if givenName != flagSetName { + t.Errorf("Unexpected result when retrieving a FlagSet's name: expected %s, but found %s", flagSetName, givenName) + } +} + func testParse(f *FlagSet, t *testing.T) { if f.Parsed() { t.Error("f.Parse() = true before Parse") @@ -854,6 +864,17 @@ func TestSetOutput(t *testing.T) { } } +func TestOutput(t *testing.T) { + var flags FlagSet + var buf bytes.Buffer + expect := "an example string" + flags.SetOutput(&buf) + fmt.Fprint(flags.Output(), expect) + if out := buf.String(); !strings.Contains(out, expect) { + t.Errorf("expected output %q; got %q", expect, out) + } +} + // This tests that one can reset the flags. This still works but not well, and is // superseded by FlagSet. func TestChangingArgs(t *testing.T) {