Add zone and region entities to provide a more hierarchical structure

lib/compute/disk.js

@@ -36,39 +36,38 @@ var COMPUTE_BASE_URL = 'https://www.googleapis.com/compute/v1/projects/';
  * Create a Disk object to interact with a Google Compute Engine disk.
  *
  * @constructor
- * @alias module:compute/disk
+ * @alias module:zone/disk
  *
  * @throws {Error} if a disk name or a zone are not provided.
  *
- * @param {module:compute} compute - The Google Compute Engine instance this 
+ * @param {module:zone} zone - The Google Compute Engine zone this 
  *     disk belongs to.
- * @param {string} name - Name of the disk.
- * @param {string} zone - Zone to which the disk belongs.
  * @param {number=} sizeGb - Size of the disk in GB.
  * @param {object=} metadata - Disk metadata.
  *
  * @example
- * var gcloud = require('gcloud');
- *
- * var compute = gcloud.compute({
- *   projectId: 'grape-spaceship-123'
+ * var gcloud = require('gcloud')({
+ *   keyFilename: '/path/to/keyfile.json'
  * });
  *
- * var disk = compute.disk('disk-1', 'europe-west1-b');
+ * var compute = gcloud.compute();
+ *
+ * var myZone = compute.zone('zone-name');
+ *
+ * var disk = myZone.disk('disk1');
  */
-function Disk(compute, name, zone, sizeGb, metadata) {
+function Disk(zone, name, sizeGb, metadata) {
   this.name = name;
   this.zone = zone;
 
-  if (!this.name) {
+  if (!util.is(this.name, 'string')) {
     throw new Error('A name is needed to use Google Cloud Compute Disk.');
   }
   if (!this.zone) {
     throw new Error('A zone is needed to use Google Cloud Compute Disk.');
   }
 
   this.sizeGb = sizeGb;
-  this.compute = compute;
   this.metadata = metadata;
 }
 
@@ -132,16 +131,16 @@ Disk.prototype.makeReq_ = function(method, path, query, body, callback) {
   var reqOpts = {
     method: method,
     qs: query,
-    uri: COMPUTE_BASE_URL + this.compute.projectId + 
-        '/zones/' + this.zone +
+    uri: COMPUTE_BASE_URL + this.zone.compute.projectId + 
+        '/zones/' + this.zone.name +
         '/disks/' + this.name + path
   };
 
   if (body) {
     reqOpts.json = body;
   }
 
-  this.compute.makeAuthorizedRequest_(reqOpts, callback);
+  this.zone.compute.makeAuthorizedRequest_(reqOpts, callback);
 };
 
 module.exports = Disk;