cmdopt2/args: add vector bind

cmdopt2/args.hpp

@@ -66,6 +66,26 @@ namespace cruft::cmdopt2 {
             return get ();
         }
 
+        template <typename ValueT>
+        BaseT
+        bind (std::vector<ValueT> &ref)
+        {
+            if (!repeat_)
+                throw std::logic_error ("vector argument with non-repeatable argument");
+
+            if constexpr (parseable<ValueT>) {
+                acceptor1 = [&ref] (char const* str) {
+                    ref.emplace_back (parse::from_string<ValueT> (str));
+                };
+            } else {
+                acceptor1 = [&ref] (char const* str) {
+                    ref.emplace_back (str);
+                };
+            }
+
+            return get ();
+        }
+
         BaseT
         get (void) const
         {