template containers in Ember

1_template_container_view.js

// A mixin for `Em.ContainerView` that allows an initial render from
// a template, followed by further additions by mutating childViews.
// Note that the template should *only* contain calls to
// `{{childView}}`
App.Mixins.TemplateContainerView = Em.Mixin.create({

  render: function() {
    if (!this.get('_renderedFromTemplate')) {
      Em.View.prototype.render.apply(this, arguments);
      this.set('_renderedFromTemplate', true);
    } else {
      return this._super.apply(this, arguments);
    }
  }

});

App.Views.TemplateContainerView = Em.ContainerView.extend(App.Mixins.TemplateContainerView);

2_child_view_helper.js

// Essentially function(name = "Em.View", options = {data: {}, hash: {}})
var parseHelperArguments = function(viewClassNameOrOptions, options) {
  var viewClass;
  if (_.isString(viewClassNameOrOptions)) {
    viewClass = Em.getPath(viewClassNameOrOptions);
    window.ember_assert( "Could not find view class %@".fmt(viewClassNameOrOptions), viewClass != null );
    options = options || {};
  } else {
    viewClass = Em.View;
    options = viewClassNameOrOptions || {};
  }

  options.data = options.data || {};
  options.hash = options.hash || {};
  return [viewClass, options];
};

var addChildView = function() {
  var parsedArguments = parseHelperArguments.apply(this, arguments),
  viewClass = parsedArguments[0],
  options = parsedArguments[1],
  parentView = options.data.view,
  childViewClass,
  childView;

  window.ember_assert( "childView can only be used inside of an App.Mixins.TemplateContainerView", App.Mixins.TemplateContainerView.detect(parentView) );

  childViewClass = Em.Handlebars.ViewHelper.viewClassFromHTMLOptions(viewClass, options.hash, this);
  childView = parentView.createChildView(childViewClass, {
    template: options.fn
  });

  parentView.get('childViews').pushObject(childView);
};

Handlebars.registerHelper('childView', addChildView);

3_usage.hdbs

{{#view App.TemplateContainerView id="main_panes"}}

  {{#childView id="dashboard"}}
    ...
  {{/childView}}

  {{#childView id="inbox"}}
    ...
  {{/childView}}

{{/view}}