Add a Client class to json_rpc_2.

pkg/json_rpc_2/lib/error_code.dart

Index: pkg/json_rpc_2/lib/error_code.dart
diff --git a/pkg/json_rpc_2/lib/error_code.dart b/pkg/json_rpc_2/lib/error_code.dart
index 96cb909a314c1b43460526939be225fef554c672..f510d8bb5541d517e0ebf69d5f81a744179c0a15 100644
--- a/pkg/json_rpc_2/lib/error_code.dart
+++ b/pkg/json_rpc_2/lib/error_code.dart
@@ -34,3 +34,14 @@ const INTERNAL_ERROR = -32603;
 /// The spec reserves the range from -32000 to -32099 for implementation-defined
 /// server exceptions, but for now we only use one of those values.
 const SERVER_ERROR = -32000;
+
+String name(int errorCode) {

[Bob Nystrom, 2014/11/03 18:43:55]

Doc comment.

[nweiz, 2014/11/04 02:22:45]

Done.

+  switch (errorCode) {
+    case PARSE_ERROR: return "parse error";
+    case INVALID_REQUEST: return "invalid request";
+    case METHOD_NOT_FOUND: return "method not found";
+    case INVALID_PARAMS: return "invalid parameters";
+    case INTERNAL_ERROR: return "internal error";
+    default: return null;

[Bob Nystrom, 2014/11/03 18:43:55]

I can see the value in not throwing an ArgumentError here since this is likely
to be called from error-handling code, but returning null seems sketchy. How
about "unknown error $errorCode"?

Or, if you only intend this to be called from the exception class, maybe move it
there or don't export it from here?

[nweiz, 2014/11/04 02:22:45]

These error codes are the ones listed in the spec, but it's valid for other
codes to be used. I want to allow users to check whether the package knows a
nice name for the error code without locking them into any behavior if it
doesn't.

[Bob Nystrom, 2014/11/04 20:28:16]

SGTM.

+  }
+}