When there are no results to display for a user you often want to tell so using a placeholder message, such as 'Sorry, no posts matched your criteria' or 'You have no recent purchases'.

I created these two helpers to make using placeholder a little bit easier.

def placeholder(message = 'Nothing to display', options = {}, &proc)
  # set default options
  o = { :class => 'placeholder', :tag => 'p' }.merge(options)

  # wrap the results of the supplied block, or
  # just print out the message
  if proc
    t = o.delete(:tag)
    concat tag(t, o, true), proc.binding
    yield
    concat "</#{t}>", proc.binding
  else
    content_tag o.delete(:tag), message, o
  end
end
  
def placeholder_unless(condition, *args, &proc)
  condition ? proc.call : concat(placeholder(args), proc.binding)
end

Now you can use it as follows:

<%= placeholder :message => 'Nothing found' %>

<% placeholder do %>
Nothing found.
<% end %>

Results in:

<p class="placeholder">Nothing found</p>

The second function allows the following usage:

<% placeholder_unless @posts.any?, 'No posts found' do %>
  <%= render :partial => @post %>
<% end %>

The point is it all results in a nice, painless message with consistent markup and styling and I find it makes my code a bit more readable.

I'm sure the code could be optimized but for now it works.