ImplicitRespondTo
=================

Use #{action_name}_#{type} methods to automatically respond_to when possible.
Yield from the presentation method to the original action.

  class PeopleController < ApplicationController
    # Accept: text/html
    def update_html
      yield
      redirect_to person_url(@person)
    rescue ActiveRecord::RecordNotSaved
      flash[:error] = "Error saving #{@person.name}"
      render :action => 'edit'
    end

    # Accept: application/xml
    def update_xml
      yield
      header['Location'] = person_url(@person)
      render :xml => @person.to_xml
    rescue ActiveRecord::RecordNotSaved
      render :xml => @person.errors.to_xml, :status => '400 Bad Request'
    end

    protected
      def update
        @person.attributes = params[:person]
        @person.save!
      end
  end