Add method to get at captured content_for

In Rails 3 the only way to get for content captured with the
content_for method in a view is to call yield from within a view.
However, sometimes is it useful to get to this data from within a
helper (for instance to provide a default value). Calling yield from
within the helper method won't work, and accessing the @_content_for
variable directly is not encouraged.

Proposed solution: add a captured_content_for method so helper methods
can legitimately access captured content. Add to /action_pack/lib/
action_view/helpers/capture_helper.rb

  # Get content previously captured with +content_for+. This is the
same as calling
  # +yield+ inside a template except that this method can be used
inside helper methods.
  def captured_content_for(name)
    @_content_for(name)
  end

Lighthouse ticket: https://rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/4537

For the benefit of those who did not check the lighouse ticket, this functionality is apparently already in Rails 3, by calling content_for without a block or second parameter. This is in fact very deliberate, as evidenced by the third line of code in the function as it stands when this was written, but just was not documented in the rdoc.

Simply calling content_for(:name) should work :slight_smile:

Yehuda Katz
Architect | Engine Yard
(ph) 718.877.1325