packer-cn/helper/enumflag/flag.go

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2016-09-17 10:34:37 -04:00
package enumflag
import "fmt"
type enumFlag struct {
target *string
options []string
}
// New returns a flag.Value implementation for parsing flags with a one-of-a-set value
func New(target *string, options ...string) *enumFlag {
return &enumFlag{target: target, options: options}
}
func (f *enumFlag) String() string {
return *f.target
}
func (f *enumFlag) Set(value string) error {
for _, v := range f.options {
if v == value {
*f.target = value
return nil
}
}
return fmt.Errorf("expected one of %q", f.options)
}