udp: slightly optimize address family property

src/udp_wrap.cc

@@ -68,6 +68,8 @@ Local<Object> AddressToJS(const sockaddr* addr);
 static Persistent<String> address_sym;
 static Persistent<String> port_sym;
 static Persistent<String> family_sym;
+static Persistent<String> ipv4_sym;
+static Persistent<String> ipv6_sym;
 static Persistent<String> buffer_sym;
 static Persistent<String> oncomplete_sym;
 static Persistent<String> onmessage_sym;
@@ -136,6 +138,8 @@ void UDPWrap::Initialize(Handle<Object> target) {
   oncomplete_sym = NODE_PSYMBOL("oncomplete");
   onmessage_sym = NODE_PSYMBOL("onmessage");
   family_sym = NODE_PSYMBOL("family");
+  ipv4_sym = NODE_PSYMBOL("IPv4");
+  ipv6_sym = NODE_PSYMBOL("IPv6");
 
   Local<FunctionTemplate> t = FunctionTemplate::New(New);
   t->InstanceTemplate()->SetInternalFieldCount(1);
@@ -449,7 +453,6 @@ Local<Object> AddressToJS(const sockaddr* addr) {
   const sockaddr_in *a4;
   const sockaddr_in6 *a6;
   int port;
-  const char *family_name;
 
   Local<Object> info = Object::New();
 
@@ -458,20 +461,18 @@ Local<Object> AddressToJS(const sockaddr* addr) {
     a6 = reinterpret_cast<const sockaddr_in6*>(addr);
     uv_inet_ntop(AF_INET6, &a6->sin6_addr, ip, sizeof ip);
     port = ntohs(a6->sin6_port);
-    family_name = "IPv6";
     info->Set(address_sym, String::New(ip));
-    info->Set(family_sym, String::New(family_name));
     info->Set(port_sym, Integer::New(port));
+    info->Set(family_sym, ipv6_sym);
     break;
 
   case AF_INET:
     a4 = reinterpret_cast<const sockaddr_in*>(addr);
     uv_inet_ntop(AF_INET, &a4->sin_addr, ip, sizeof ip);
     port = ntohs(a4->sin_port);
-    family_name = "IPv4";
     info->Set(address_sym, String::New(ip));
-    info->Set(family_sym, String::New(family_name));
     info->Set(port_sym, Integer::New(port));
+    info->Set(family_sym, ipv4_sym);
     break;
 
   default: