Parse comma-separated multiple values.

lib/src/option.dart

Index: lib/src/option.dart
diff --git a/lib/src/option.dart b/lib/src/option.dart
index 4045bce1e0b528b7d857631d75b1bbd38cdd49a8..07e87f68196b553490a7649ebd8a41c28b99274a 100644
--- a/lib/src/option.dart
+++ b/lib/src/option.dart
@@ -13,9 +13,10 @@ import 'dart:collection';
 Option newOption(String name, String abbreviation, String help,
     String valueHelp, List<String> allowed, Map<String, String> allowedHelp,
     defaultValue, Function callback, OptionType type,
-    {bool negatable, bool hide: false}) {
+    {bool negatable, bool splitCommas, bool hide: false}) {
   return new Option._(name, abbreviation, help, valueHelp, allowed, allowedHelp,
-      defaultValue, callback, type, negatable: negatable, hide: hide);
+      defaultValue, callback, type, negatable: negatable,
+      splitCommas: splitCommas, hide: hide);
 }
 
 /// A command-line option. Includes both flags and options which take a value.
@@ -30,6 +31,7 @@ class Option {
   final Map<String, String> allowedHelp;
   final OptionType type;
   final bool negatable;
+  final bool splitCommas;
   final bool hide;
 
   /// Whether the option is boolean-valued flag.
@@ -43,13 +45,20 @@ class Option {
 
   Option._(this.name, this.abbreviation, this.help, this.valueHelp,
       List<String> allowed, Map<String, String> allowedHelp, this.defaultValue,
-      this.callback, this.type, {this.negatable, this.hide: false})
+      this.callback, OptionType type, {this.negatable, bool splitCommas,
+      this.hide: false})
       : this.allowed = allowed == null
           ? null
           : new UnmodifiableListView(allowed),
         this.allowedHelp = allowedHelp == null
             ? null
-            : new UnmodifiableMapView(allowedHelp) {
+            : new UnmodifiableMapView(allowedHelp),
+        this.type = type,
+        // If the user doesn't specify [splitCommas], it defaults to true for
+        // multiple options.
+        this.splitCommas = splitCommas == null
+            ? type == OptionType.MULTIPLE
+            : splitCommas {
     if (name.isEmpty) {
       throw new ArgumentError('Name cannot be empty.');
     } else if (name.startsWith('-')) {