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: # # # # layout with js # # # # <%= @content_for_layout %> # # # # 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(*args, &block) # execute the block buffer = eval("_erbout", block.binding) pos = buffer.length block.call(*args) # 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_ # 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. # # NOTE: Beware that content_for is ignored in caches. So you shouldn't use it # for elements that are going to be fragment cached. def content_for(name, &block) eval "@content_for_#{name} = (@content_for_#{name} || '') + capture(&block)" end end end end