// Test if the named flag is a boolean flag.
func isBooleanFlag(name string, f *flag.FlagSet) bool {
flag := f.Lookup(name)
if flag == nil {
return false
}
return flag.Value.Type() == "bool"
}
// Test if the named flag is a boolean flag.
func isBooleanShortFlag(name string, f *flag.FlagSet) bool {
result := false
f.VisitAll(func(f *flag.Flag) {
if f.Shorthand == name && f.Value.Type() == "bool" {
result = true
}
})
return result
}
// SetFlagsFromEnv parses all registered flags in the given flagset,
// and if they are not already set it attempts to set their values from
// environment variables. Environment variables take the name of the flag but
// are UPPERCASE, and any dashes are replaced by underscores. Environment
// variables additionally are prefixed by the given string followed by
// and underscore. For example, if prefix=PREFIX: some-flag => PREFIX_SOME_FLAG
func SetFlagsFromEnv(fs *flag.FlagSet, prefix string) (err error) {
alreadySet := make(map[string]bool)
fs.Visit(func(f *flag.Flag) {
alreadySet[f.Name] = true
})
fs.VisitAll(func(f *flag.Flag) {
if !alreadySet[f.Name] {
key := prefix + "_" + strings.ToUpper(strings.Replace(f.Name, "-", "_", -1))
val := os.Getenv(key)
if val != "" {
if serr := fs.Set(f.Name, val); serr != nil {
err = fmt.Errorf("invalid value %q for %s: %v", val, key, serr)
}
}
}
})
return err
}
// MarkFlagFilename adds the BashCompFilenameExt annotation to the named flag in the flag set, if it exists.
// Generated bash autocompletion will select filenames for the flag, limiting to named extensions if provided.
func MarkFlagFilename(flags *pflag.FlagSet, name string, extensions ...string) error {
return flags.SetAnnotation(name, BashCompFilenameExt, extensions)
}
// MarkFlagRequired adds the BashCompOneRequiredFlag annotation to the named flag in the flag set, if it exists.
func MarkFlagRequired(flags *pflag.FlagSet, name string) error {
return flags.SetAnnotation(name, BashCompOneRequiredFlag, []string{"true"})
}