Eliminated named constants for instances of remoting.Error.

remoting/webapp/crd/js/error.js

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 'use strict';
 
 /** @suppress {duplicate} */
 var remoting = remoting || {};
 
 /**
  * A wrapper for remoting.Error.Tag.  Having a wrapper makes it
  * possible to use instanceof checks on caught exceptions.  It also
  * allows adding more detailed error information if desired.
  *
  * @constructor
  * @param {remoting.Error.Tag} tag
  * @param {string=} opt_message
  */
 remoting.Error = function(tag, opt_message) {
   /** @const {remoting.Error.Tag} */
   this.tag = tag;
 
   /** @const {?string} */
   this.message = opt_message || null;
 };
 
 /**
+ * Checks the type of an error.  This method is more typesafe than
+ * using ==.

[Jamie, 2015/03/12 21:40:11]

If you make tag_ private, there's no need for the second sentence (since this
will be the only way to check the type of an error).

[John Williams, 2015/03/13 00:26:35]

Done.

+ * @param {remoting.Error.Tag} tag
+ * @return {boolean} True if this object has the specified tag.
+ */
+remoting.Error.prototype.hasTag = function(tag) {
+  return this.tag == tag;
+};
+
+
+/**
  * @return {boolean} True if this object represents an error
  *     condition.
  */
 remoting.Error.prototype.isError = function() {

[Jamie, 2015/03/12 21:40:11]

I think we should remove this method. It's not widely-used and it's equivalent
to hasTag(NONE). It's also not obvious to me that it should return true for
CANCELLED.

[John Williams, 2015/03/13 00:26:35]

I changed it to isNone to make it more clear, but I still think it's worth
having since it's called in 7 places, not counting unit tests.

-  return this.tag != remoting.Error.Tag.NONE;
+  return !this.hasTag(remoting.Error.Tag.NONE);
 };
 
 /**
+ * Convenience method for creating the second most common error type.
+ * @return {!remoting.Error}
+ */
+remoting.Error.none = function() {
+  return new remoting.Error(remoting.Error.Tag.NONE);
+};
+
+/**
+ * Convenience method for creating the most common error type.
+ * @return {!remoting.Error}
+ */
+remoting.Error.unexpected = function() {
+  return new remoting.Error(remoting.Error.Tag.UNEXPECTED);
+};
+
+/**
  * @enum {string} All error messages from messages.json
  */
 remoting.Error.Tag = {
   NONE: '',
 
   // Used to signify that an operation was cancelled by the user. This should
   // not normally cause the error text to be shown to the user, so the
   // i18n-content prefix is not needed in this case.
   CANCELLED: '__CANCELLED__',
 
@@ skipping 17 matching lines @@
   // TODO(garykac): Move app-specific errors into separate location.
   APP_NOT_AUTHORIZED: /*i18n-content*/'ERROR_APP_NOT_AUTHORIZED'
 };
 
 // A whole bunch of semi-redundant constants, mostly to reduce to size
 // of the diff that introduced the remoting.Error class.
 //
 // Please don't add any more constants here; just call the
 // remoting.Error constructor directly
 
-/** @const */
-remoting.Error.NONE = new remoting.Error(remoting.Error.Tag.NONE);
-
-/** @const */
-remoting.Error.CANCELLED =
-  new remoting.Error(remoting.Error.Tag.CANCELLED);
-
-/** @const */
-remoting.Error.INVALID_ACCESS_CODE =
-  new remoting.Error(remoting.Error.Tag.INVALID_ACCESS_CODE);
-
-/** @const */
-remoting.Error.MISSING_PLUGIN =
-  new remoting.Error(remoting.Error.Tag.MISSING_PLUGIN);
-
-/** @const */
-remoting.Error.AUTHENTICATION_FAILED =
-  new remoting.Error(remoting.Error.Tag.AUTHENTICATION_FAILED);
-
-/** @const */
-remoting.Error.HOST_IS_OFFLINE =
-  new remoting.Error(remoting.Error.Tag.HOST_IS_OFFLINE);
-
-/** @const */
-remoting.Error.INCOMPATIBLE_PROTOCOL =
-  new remoting.Error(remoting.Error.Tag.INCOMPATIBLE_PROTOCOL);
-
-/** @const */
-remoting.Error.BAD_PLUGIN_VERSION =
-  new remoting.Error(remoting.Error.Tag.BAD_PLUGIN_VERSION);
-
-/** @const */
-remoting.Error.NETWORK_FAILURE =
-  new remoting.Error(remoting.Error.Tag.NETWORK_FAILURE);
-
-/** @const */
-remoting.Error.HOST_OVERLOAD =
-  new remoting.Error(remoting.Error.Tag.HOST_OVERLOAD);
-
-/** @const */
-remoting.Error.UNEXPECTED =
-  new remoting.Error(remoting.Error.Tag.UNEXPECTED);
-
-/** @const */
-remoting.Error.SERVICE_UNAVAILABLE =
-  new remoting.Error(remoting.Error.Tag.SERVICE_UNAVAILABLE);
-
-/** @const */
-remoting.Error.NOT_AUTHENTICATED =
-  new remoting.Error(remoting.Error.Tag.NOT_AUTHENTICATED);
-
-/** @const */
-remoting.Error.NOT_FOUND =
-  new remoting.Error(remoting.Error.Tag.NOT_FOUND);
-
-/** @const */
-remoting.Error.INVALID_HOST_DOMAIN =
-  new remoting.Error(remoting.Error.Tag.INVALID_HOST_DOMAIN);
-
-/** @const */
-remoting.Error.P2P_FAILURE =
-  new remoting.Error(remoting.Error.Tag.P2P_FAILURE);
-
-/** @const */
-remoting.Error.REGISTRATION_FAILED =
-  new remoting.Error(remoting.Error.Tag.REGISTRATION_FAILED);
-
-/** @const */
-remoting.Error.NOT_AUTHORIZED =
-  new remoting.Error(remoting.Error.Tag.NOT_AUTHORIZED);
-
-/** @const */
-remoting.Error.APP_NOT_AUTHORIZED =
-  new remoting.Error(remoting.Error.Tag.APP_NOT_AUTHORIZED);
-
 /**
  * @param {number} httpStatus An HTTP status code.
  * @return {!remoting.Error} The remoting.Error enum corresponding to the
  *     specified HTTP status code.
  */
 remoting.Error.fromHttpStatus = function(httpStatus) {
   if (httpStatus == 0) {
-    return remoting.Error.NETWORK_FAILURE;
+    return new remoting.Error(remoting.Error.Tag.NETWORK_FAILURE);
   } else if (httpStatus >= 200 && httpStatus < 300) {
-    return remoting.Error.NONE;
+    return remoting.Error.none();
   } else if (httpStatus == 400 || httpStatus == 401) {
-    return remoting.Error.AUTHENTICATION_FAILED;
+    return new remoting.Error(remoting.Error.Tag.AUTHENTICATION_FAILED);
   } else if (httpStatus == 403) {
-    return remoting.Error.NOT_AUTHORIZED;
+    return new remoting.Error(remoting.Error.Tag.NOT_AUTHORIZED);
   } else if (httpStatus == 404) {
-    return remoting.Error.NOT_FOUND;
+    return new remoting.Error(remoting.Error.Tag.NOT_FOUND);
   } else if (httpStatus >= 500 && httpStatus < 600) {
-    return remoting.Error.SERVICE_UNAVAILABLE;
+    return new remoting.Error(remoting.Error.Tag.SERVICE_UNAVAILABLE);
   } else {
     console.warn('Unexpected HTTP error code: ' + httpStatus);
-    return remoting.Error.UNEXPECTED;
+    return remoting.Error.unexpected();
   }
 };
 
 /**
  * Create an error-handling function suitable for passing to a
  * Promise's "catch" method.
  *
  * @param {function(!remoting.Error):void} onError
  * @return {function(*):void}
  */
 remoting.Error.handler = function(onError) {
   return function(/** * */ error) {
     if (error instanceof remoting.Error) {
       onError(/** @type {!remoting.Error} */ (error));
     } else {
       console.error('Unexpected error: %o', error);
-      onError(remoting.Error.UNEXPECTED);
+      onError(remoting.Error.unexpected());
     }
   };
 };