Checkout of Instiki Trunk 1/21/2007.

vendor/rails/actionpack/lib/action_view/partials.rb

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+module ActionView
+  # There's also a convenience method for rendering sub templates within the current controller that depends on a single object 
+  # (we call this kind of sub templates for partials). It relies on the fact that partials should follow the naming convention of being 
+  # prefixed with an underscore -- as to separate them from regular templates that could be rendered on their own. 
+  #
+  # In a template for Advertiser#account:
+  #
+  #  <%= render :partial => "account" %>
+  #
+  # This would render "advertiser/_account.rhtml" and pass the instance variable @account in as a local variable +account+ to 
+  # the template for display.
+  #
+  # In another template for Advertiser#buy, we could have:
+  #
+  #   <%= render :partial => "account", :locals => { :account => @buyer } %>
+  #
+  #   <% for ad in @advertisements %>
+  #     <%= render :partial => "ad", :locals => { :ad => ad } %>
+  #   <% end %>
+  #
+  # This would first render "advertiser/_account.rhtml" with @buyer passed in as the local variable +account+, then render 
+  # "advertiser/_ad.rhtml" and pass the local variable +ad+ to the template for display.
+  #
+  # == Rendering a collection of partials
+  #
+  # The example of partial use describes a familiar pattern where a template needs to iterate over an array and render a sub
+  # template for each of the elements. This pattern has been implemented as a single method that accepts an array and renders
+  # a partial by the same name as the elements contained within. So the three-lined example in "Using partials" can be rewritten
+  # with a single line:
+  #
+  #   <%= render :partial => "ad", :collection => @advertisements %>
+  #
+  # This will render "advertiser/_ad.rhtml" and pass the local variable +ad+ to the template for display. An iteration counter
+  # will automatically be made available to the template with a name of the form +partial_name_counter+. In the case of the 
+  # example above, the template would be fed +ad_counter+.
+  #
+  # NOTE: Due to backwards compatibility concerns, the collection can't be one of hashes. Normally you'd also just keep domain objects,
+  # like Active Records, in there.
+  # 
+  # == Rendering shared partials
+  #
+  # Two controllers can share a set of partials and render them like this:
+  #
+  #   <%= render :partial => "advertisement/ad", :locals => { :ad => @advertisement } %>
+  #
+  # This will render the partial "advertisement/_ad.rhtml" regardless of which controller this is being called from.
+  module Partials
+    # Deprecated, use render :partial
+    def render_partial(partial_path, local_assigns = nil, deprecated_local_assigns = nil) #:nodoc:
+      path, partial_name = partial_pieces(partial_path)
+      object = extracting_object(partial_name, local_assigns, deprecated_local_assigns)
+      local_assigns = extract_local_assigns(local_assigns, deprecated_local_assigns)
+      local_assigns = local_assigns ? local_assigns.clone : {}
+      add_counter_to_local_assigns!(partial_name, local_assigns)
+      add_object_to_local_assigns!(partial_name, local_assigns, object)
+
+      if logger
+        ActionController::Base.benchmark("Rendered #{path}/_#{partial_name}", Logger::DEBUG, false) do
+          render("#{path}/_#{partial_name}", local_assigns)
+        end
+      else
+        render("#{path}/_#{partial_name}", local_assigns)
+      end
+    end
+
+    # Deprecated, use render :partial, :collection
+    def render_partial_collection(partial_name, collection, partial_spacer_template = nil, local_assigns = nil) #:nodoc:
+      collection_of_partials = Array.new
+      counter_name = partial_counter_name(partial_name)
+      local_assigns = local_assigns ? local_assigns.clone : {}
+      collection.each_with_index do |element, counter|
+        local_assigns[counter_name] = counter
+        collection_of_partials.push(render_partial(partial_name, element, local_assigns))
+      end
+
+      return " " if collection_of_partials.empty?
+
+      if partial_spacer_template
+        spacer_path, spacer_name = partial_pieces(partial_spacer_template)
+        collection_of_partials.join(render("#{spacer_path}/_#{spacer_name}"))
+      else
+        collection_of_partials.join
+      end
+    end
+    
+    alias_method :render_collection_of_partials, :render_partial_collection
+    
+    private
+      def partial_pieces(partial_path)
+        if partial_path.include?('/')
+          return File.dirname(partial_path), File.basename(partial_path)
+        else
+          return controller.class.controller_path, partial_path
+        end
+      end
+
+      def partial_counter_name(partial_name)
+        "#{partial_name.split('/').last}_counter".intern
+      end
+      
+      def extracting_object(partial_name, local_assigns, deprecated_local_assigns)
+        if local_assigns.is_a?(Hash) || local_assigns.nil?
+          controller.instance_variable_get("@#{partial_name}")
+        else
+          # deprecated form where object could be passed in as second parameter
+          local_assigns
+        end
+      end
+      
+      def extract_local_assigns(local_assigns, deprecated_local_assigns)
+        local_assigns.is_a?(Hash) ? local_assigns : deprecated_local_assigns
+      end
+      
+      def add_counter_to_local_assigns!(partial_name, local_assigns)
+        counter_name = partial_counter_name(partial_name)
+        local_assigns[counter_name] = 1 unless local_assigns.has_key?(counter_name)
+      end
+
+      def add_object_to_local_assigns!(partial_name, local_assigns, object)
+        local_assigns[partial_name.intern] ||=
+          if object.is_a?(ActionView::Base::ObjectWrapper)
+            object.value
+          else
+            object
+          end || controller.instance_variable_get("@#{partial_name}")
+      end
+  end
+end