first work towards 'async' view helper

lib/template/async_partial.js

@@ -0,0 +1,39 @@
+(function() {
+  'use strict';
+
+  var isPromise = require('is-promise');
+
+  function AsyncPartial(handler, opts, parent) {
+    this.render = function(cb) {
+      var self = this;
+
+      if (typeof handler === 'function') {
+        handler(function (err, result) {
+          if (err) {
+            onError(err);
+            cb('');
+            return;
+          }
+
+          cb(result);
+        });
+      } else if (isPromise(handler)) {
+        handler
+          .then(function (result) {
+            cb(result);
+          })
+          .catch(function (err) {
+            onError(err);
+            cb('');
+          });
+      }
+
+      function onError(err) {
+        throw err;
+      }
+    }
+  }
+
+  exports.AsyncPartial = AsyncPartial;
+
+}());

lib/template/partial.js

@@ -7,7 +7,8 @@
     , path = require('path')
     , fs = require('fs')
     , utils = require('utilities')
-    , cache = {};
+    , cache = {}
+    , AsyncPartial = require('./async_partial').AsyncPartial;
 
   Partial = function (templatePath, data, parent) {
     var self = this;
@@ -26,6 +27,15 @@
       self.addChild(child);
       return '###partial###' + child.id
     };
+
+    // Hang a `async` method on the execution-context for the
+    // template rendering (e.g., will be the EJS global `async`
+    // function to add async sub-templates
+    this.data.async = function (handler, opts) {
+      var child = new AsyncPartial(handler, opts, self);
+      self.addChild(child);
+      return '###partial###' + child.id;
+    };
   };
 
   Partial.prototype = new (function () {

package.json

@@ -13,6 +13,7 @@
   "dependencies": {
     "barista": "0.2.x",
     "chalk": "^0.4.0",
+    "is-promise": "^2.0.0",
     "jake": "8.0.x",
     "mime": "1.2.x",
     "model": "6.0.x",

test/templates/async_partial.js

@@ -0,0 +1,58 @@
+(function() {
+  'use strict';
+
+  require('../../lib/geddy');
+
+  var assert = require('assert')
+    , Partial = require('../../lib/template/partial').Partial
+    , tests;
+
+  // TODO: how to actually inject template code?
+
+  geddy.templateRegistry = {
+    'app/views/foo/baz': {
+      file: 'app/views/foo/baz.html.ejs'
+    , ext: '.ejs'
+    , baseName: 'baz'
+    , baseNamePath: 'app/views/foo/baz'
+    }
+
+  , 'app/views/foo/bar': {
+      file: 'app/views/foo/bar.html.ejs'
+    , ext: '.ejs'
+    , baseName: 'bar'
+    , baseNamePath: 'app/views/foo/bar'
+    }
+  };
+
+  geddy.viewHelpers.callbackHelper = function() {
+    return function(cb) {
+      cb(null, 'callback helper result');
+    };
+  };
+
+  geddy.viewHelpers.promiseHelper = function() {
+    return new Promise(function (resolve, reject) {
+      resolve('promise helper result');
+    });
+  };
+
+  tests = {
+
+    'callback helper': function () {
+      var p = new Partial('foo/bar', {})
+        , data = p.getTemplateData();
+      assert.ok(data);
+    }
+
+  , 'promise helper': function () {
+      var pParent = new Partial('app/views/foo/baz', {})
+      var pSub = new Partial('bar', {}, pParent)
+        , data = pSub.getTemplateData();
+      assert.ok(data);
+    }
+
+  };
+
+  module.exports = tests;
+}());