Added CaptureHelper with CaptureHelper#capture and CaptureHelper#content_for....

Added CaptureHelper with CaptureHelper#capture and CaptureHelper#content_for. See documentation in helper #837 [Tobias Luetke] git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@907 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

Added CaptureHelper with CaptureHelper#capture and CaptureHelper#content_for....
Added CaptureHelper with CaptureHelper#capture and CaptureHelper#content_for. See documentation in helper #837 [Tobias Luetke] git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@907 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
823a918a · David Heinemeier Hansson · 90f78e2b · 823a918a · 823a918a
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actionpack/CHANGELOG actionpack/CHANGELOG +2 -0

actionpack/lib/action_view/helpers/capture_helper.rb actionpack/lib/action_view/helpers/capture_helper.rb +95 -0

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--- a/actionpack/CHANGELOG
+++ b/actionpack/CHANGELOG
 *SVN*
+* Added CaptureHelper with CaptureHelper#capture and CaptureHelper#content_for. See documentation in helper #837 [Tobias Luetke]
 * Fixed :anchor use in url_for #821 [Nicholas Seckar]
 * Removed the reliance on PATH_INFO as it was causing problems for caching and inhibited the new non-vhost support #822 [Nicholas Seckar]

--- a/actionpack/lib/action_view/helpers/capture_helper.rb
+++ b/actionpack/lib/action_view/helpers/capture_helper.rb
+module ActionView
+  module Helpers
+    # Capture lets you extract parts of code into instance variables which
+    # can be used in other points of the template or even layout file.
+    #
+    # == Capturing a block into an instance variable
+    #
+    #   <% @script = capture do %>
+    #     [some html...]
+    #   <% end %>
+    #  
+    #
+    # == Add javascript to header using content_for
+    #
+    # content_for("name") is a wrapper for capture which will store the 
+    # fragment in a instance variable similar to @content_for_layout.
+    #
+    # layout.rhtml:
+    #
+    #   <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
+    #   <head>
+    #	    <title>layout with js</title>
+    #	    <script type="text/javascript">
+    #	    <%= @content_for_script %>
+    #   	</script>
+    #   </head>
+    #   <body>
+    #     <%= @content_for_layout %>
+    #   </body>
+    #   </html>
+    #
+    # view.rhtml
+    #   
+    #   This page shows an alert box!
+    #
+    #   <% content_for("script") do %>
+    #     alert('hello world')
+    #   <% end %>
+    #
+    #   Normal view text
+    module CaptureHelper
+      # Capture allows you to extract a part of the template into an 
+      # instance variable. You can use this instance variable anywhere
+      # in your templates and even in your layout. 
+      # 
+      # Example:
+      # 
+      #   <% @greeting = capture do %>
+      #     Welcome To my shiny new web page!
+      #   <% end %>      
+      def capture(&block)
+        # execute the block
+        buffer = eval("_erbout", block.binding)
+        pos = buffer.length
+        block.call
+        # extract the block 
+        data = buffer[pos..-1]
+        # replace it in the original with empty string
+        buffer[pos..-1] = ''
+        data
+      end
+      # Content_for will store the given block
+      # in an instance variable for later use in another template
+      # or in the layout. 
+      # 
+      # The name of the instance variable is content_for_<name> 
+      # to stay consistent with @content_for_layout which is used 
+      # by ActionView's layouts
+      # 
+      # Example:
+      # 
+      #   <% content_for("header") do %>
+      #     alert('hello world')
+      #   <% end %>
+      #
+      # You can use @content_for_header anywhere in your templates
+      def content_for(name, &block)                      
+        base = controller.instance_variable_get(instance_var_name(name)) || ""
+        data = capture(&block)
+        controller.instance_variable_set(instance_var_name(name), base + data)
+        data
+      end
+      private
+        def instance_var_name(name) #:nodoc#
+          "@content_for_#{name}"
+        end
+    end
+  end
+end