Flash messages and form errors in good way

_flash_messages.html.haml

- if flash.keys.size > 0
  .flash-messages
    - flash.each do |type, message| 
      %div(class="flash-message flash-#{type}")= message

_form_errors.html.haml

- if object.errors.any?
  .error-explanation
    %h3=t ".#{object.class.to_s.underscore}.header", :default => t(".header")
    %ul
      - object.errors.full_messages.each do |msg|
        %li= msg

application_helper.rb

module ApplicationHelper
  # It displays flash messages.
  def flash_messages
    render :partial => "shared/flash_message"
  end

  # It displays validation errors for given object. Here is the HAML example:
  # 
  #   - form_for @user do |f|
  #     = form_errors(f)
  #     -# ...
  #   
  #   - form_for "/sessions/login" do |f|
  #     = form_errors(@session)
  #     -# ...
  def form_errors(object)
    object = object.object if object.respond_to? :object
    # I've used locals here because object params doesn't work properly. 
    render :partial => "shared/form_errors", :locals => { :object => object }
  end

  # ...
end