Merge pull request #19 from walle/add_default_value_to_usage

Add default values to usage

1 files changed, 10 insertions, 0 deletions

diff --git a/usage.go b/usage.go
index 9404015..fa01229 100644
--- a/usage.go
+++ b/usage.go
@@ -5,6 +5,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"reflect"
 	"strings"
 )
 
@@ -101,6 +102,15 @@ func printOption(w io.Writer, spec *spec) {
 		}
 		fmt.Fprint(w, spec.help)
 	}
+	// Check if spec.dest is zero value or not
+	// If it isn't a default value have been added
+	v := spec.dest
+	if v.IsValid() {
+		z := reflect.Zero(v.Type())
+		if v.Interface() != z.Interface() {
+			fmt.Fprintf(w, " [default: %v]", v)
+		}
+	}
 	fmt.Fprint(w, "\n")
 }