title: render default template when requested template is missing in Rails
body: <p>For a plugin I want to hack the following feature into Rails:</p>
  
  <p>When a (partial) template does not exist (regardless of the format) I want to render a default template.</p>
  
  <p>So say I call an action 'users/index' if users/index.html.erb does not (or other format) exist, 'default/index.html.erb' should be rendered. </p>
  
  <p>Similarly, If I call an action 'locations/edit' and 'locations/edit.html.erb' does not exist, 'default/edit.html.erb' should be rendered</p>
  
  <p>For partials, If I call an action 'locations/index' and the template 'locations/index.html.erb' calls the partial 'locations/_location' which does not exist, it should render 'default/_object'</p>
  
  <p>The solution is seek gives me access to the templates variables (e.g. @users, @locations) and information on the requested path (e.g. users/index, locations/edit). And it should also work with partials.</p>
  
  <p>I have thought of some options which I'll post below. None of them are completely satisfactory.</p>