I disagree… I think having a little markup in your helpers is perfectly acceptable. They are “help” for your presentation after all. I think the main mistake people make is using helpers for things that should go into a partial.

def flash_helper
[:notice, :warning, :message].map { |f| content_tag(:div, flash[f], :class => f) if flash[f] }
end

def flash_helper
[:notice, :warning, :message].map { |f| content_tag(:div, flash[f], :class => type) if flash[f] }
end

def render_flash_messages
  result = ''
  for type in [:notice, :warning, :message]
    message = flash[type]
    result #{message}”
  end
  result
end

I should also note that content_tag is quite slow, which is why I used the inline string to generate HTML. If a partial was used instead (for the MVC purist, which I am usually) that would have incurred an even higher performance hit, which in most of my applications isn’t worth the extra purity of the code.

  def render_flash_messages
    result = ''
    for type in [:notice, :warning, :message]
      message = flash[type]
      # commented out content_tag, while cleaner is very inefficient
      #content_tag('div', message, :class => type) if message
      # using string inline method...
      result #{message}"
    end
    result
  end

A few things should be noted:
flash_helper and render_flash_messages are roughly equivalent performance wiseflash_helper has a defect in it. Line 8 should read: fl = fl + ”#{flash[name]}”