Rails - Nov 2007 - Trouble writing a plugin with view helpers

Hi,

I am writing a plugin with some view helpers, and have hit a wall. The
helper method uses a class that specifies specific behavior depending
on an model object. The problem is that I need that class to be able
to use the rest of Rails helpers, such as content_tag.

The class extends a general class which is mixed with a module. It
uses method_missing to define methods to the class used by the helper
method if it hasn''t been defined.

This is the code with the problem:
--------
init.rb
--------
#The other stuff plus
ActionView::Base.send :include, Microformat::ViewHelpers

-------------------------------------
microformat_helper.rb
-------------------------------------
module Microformat
  module ViewHelpers

    # User will type:
    # <% geo_for location, "Location:", :geo_tag
=> :div, :internal_tag => :span do |g| %>
    #   <% g.latitude "Latitude: #{location.latitude}, " %>
    #   <% g.longitude "Longitude: #{location.longitude}" %>
    # <% end %>

    # Output
    #  <div class="geo">GEO:
    #    <span class="latitude">37.386013</span>,
    #    <span class="longitude">-122.082932</span>
    #  </div>

    def geo_for(geo_obj, text, options = {})
      raise ArgumentError, "Missing block" unless block_given?
      geo_tag = options.delete :geo_tag
      internal_tag = options.delete :internal_tag
      content_tag geo_tag, :class => "geo" do
        text
        yield GeoInternal.new(internal_tag, geo_obj)
      end
    end
  end

  module MicroformatCreator

    def method_missing(name, *args)
      block = Proc.new{|b_args, b_name|
        tag, text = b_args.pop, b_args.pop
        content_tag tag, :class => b_name do
          text unless text.nil?
        end
      }
      self.class.send(:define_method, name, block)
      block.call(args, name)
    end
  end

  class InvalidMicroformatField < StandardError
  end

  class Microformat
    include MicroformatCreator

    def initialize(tag, m_obj)
      @i_tag = tag
      @m_obj = m_obj
    end

    def method_missing(name, *args)
      raise InvalidMicroformatField, "The field #{name} does not
exist" unless @m_obj.attribute_names.include?(name.to_s)
      args.push @i_tag
      super(name, args)
    end
  end

  class GeoInternal < Microformat
    def initialize(tag, g_obj)
      super(tag, g_obj)
    end
  end
end

What is happening right now when I use ''geo_for'' in a view is
that the
content_tag in the MicroformatCreator method_missing is caught by the
raise of the Microformat class. I need to find a way to make the rails
helper methods to the GeoInternal class.

I have tried including MicroformatGenerator in init.rb, hoping then
that method missing could call content_tag, but it didn''t work. I also
tried including to MicroformatGenerator the necessary Rails helpers,
such as TagHelper, but then I got an error related to _erbout.

If anyone has a workaround to make the helpers available to
GeoInternal it would be great, or let me know if this is not possible.

Thanks,

Alan

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