Better help for maps.

help_test.go

@@ -71,7 +71,7 @@ Flags:
   --bool                 A bool flag with very long help that wraps a lot and is
                          verbose and is really verbose.
   --slice=STR,...        A slice of strings.
-  --map=KEY=VALUE    A map of strings to ints.
+  --map=KEY=VALUE;...    A map of strings to ints.
   --required             A required flag.
 
 Commands:
@@ -111,7 +111,7 @@ Flags:
   --bool                 A bool flag with very long help that wraps a lot and is
                          verbose and is really verbose.
   --slice=STR,...        A slice of strings.
-  --map=KEY=VALUE     A map of strings to ints.
+  --map=KEY=VALUE;...    A map of strings to ints.
   --required             A required flag.
 
   --flag=STRING          Nested flag under two.

model.go

@@ -357,7 +357,7 @@ func (f *Flag) FormatPlaceHolder() string {
 		return f.PlaceHolder + tail
 	}
 	if f.Value.IsMap() {
-		return "KEY=VALUE" + tail
+		return "KEY=VALUE;..."
 	}
 	return strings.ToUpper(f.Name) + tail
 }

resolver.go

@@ -70,6 +70,16 @@ func jsonDecodeValue(sep rune, value interface{}) (string, error) {
 			out = append(out, sel)
 		}
 		return JoinEscaped(out, sep), nil
+	case map[string]interface{}:
+		out := []string{}
+		for key, el := range v {
+			sel, err := jsonDecodeValue(sep, el)
+			if err != nil {
+				return "", err
+			}
+			out = append(out, fmt.Sprintf("%s=%s", key, sel))
+		}
+		return JoinEscaped(out, ';'), nil
 	case bool:
 		if v {
 			return "true", nil