Add long-option support

1 files changed, 16 insertions, 4 deletions

diff --git a/err.go b/err.go
index cbe96b4..23692fa 100644
--- a/err.go
+++ b/err.go
@@ -4,16 +4,28 @@ import "fmt"
 
 // A BadOptionError describes an option that the user attempted to pass
 // which the developer did not register.
-type BadOptionError rune
+type BadOptionError struct {
+	r rune
+	s string
+}
 
 func (e BadOptionError) Error() string {
-	return fmt.Sprintf("unknown option ‘%c’", e)
+	if e.r != 0 {
+		return fmt.Sprintf("unknown option ‘-%c’", e.r)
+	}
+	return fmt.Sprintf("unknown option ‘--%s’", e.s)
 }
 
 // A NoArgumentError describes an option that the user attempted to pass
 // without an argument, which required an argument.
-type NoArgumentError rune
+type NoArgumentError struct {
+	r rune
+	s string
+}
 
 func (e NoArgumentError) Error() string {
-	return fmt.Sprintf("expected argument for option ‘%c’", e)
+	if e.r != 0 {
+		return fmt.Sprintf("expected argument for option ‘-%c’", e.r)
+	}
+	return fmt.Sprintf("expected argument for option ‘--%s’", e.s)
 }