Provides functionality for “capturing” content in one place and reusing this content elsewhere.
For example, suppose you want the sidebar of your site to contain a short summary of the item. You could put the summary in the meta file, but that’s not possible when the summary contains eRuby. You could also put the sidebar inside the actual item, but that’s not very pretty. Instead, you write the summary on the item itself, but capture it, and print it in the sidebar layout.
This helper has been tested with ERB and Haml. Other filters may not work correctly.
@example Capturing content for a summary
<% content_for :summary do %> <p>On this item, nanoc is introduced, blah blah.</p> <% end %>
@example Showing captured content in a sidebar
<div id="sidebar"> <h3>Summary</h3> <%= content_for(@item, :summary) || '(no summary)' %> </div>
@example Showing captured content in a sidebar the old, deprecated way (do not use or I will become very angry)
<div id="sidebar"> <h3>Summary</h3> <%= @item[:content_for_summary] || '(no summary)' %> </div>
Evaluates the given block and returns its contents. The contents of the block is not outputted.
@return [String] The captured result
# File lib/nanoc/helpers/capturing.rb, line 150 def capture(&block) # Get erbout so far erbout = eval('_erbout', block.binding) erbout_length = erbout.length # Execute block block.call # Get new piece of erbout erbout_addition = erbout[erbout_length..-1] # Remove addition erbout[erbout_length..-1] = '' # Depending on how the filter outputs, the result might be a # single string or an array of strings (slim outputs the latter). erbout_addition = erbout_addition.join if erbout_addition.is_a? Array # Done. erbout_addition end
@overload content_for(name, &block)
Captures the content inside the block and stores it so that it can be referenced later on. The same method, {#content_for}, is used for getting the captured content as well as setting it. When capturing, the content of the block itself will not be outputted. For backwards compatibility, it is also possible to fetch the captured content by getting the contents of the attribute named `content_for_` followed by the given name. This way of accessing captures is deprecated. @param [Symbol, String] name The base name of the attribute into which the content should be stored @return [void]
@overload content_for(item, name)
Fetches the capture with the given name from the given item and returns it. @param [Nanoc::Item] item The item for which to get the capture @param [Symbol, String] name The name of the capture to fetch @return [String] The stored captured content
# File lib/nanoc/helpers/capturing.rb, line 99 def content_for(*args, &block) if block_given? # Set content # Get args if args.size != 1 raise ArgumentError, "expected 1 argument (the name " + "of the capture) but got #{args.size} instead" end name = args[0] # Capture and store content = capture(&block) @site.captures_store[@item, name.to_sym] = content else # Get content # Get args if args.size != 2 raise ArgumentError, "expected 2 arguments (the item " + "and the name of the capture) but got #{args.size} instead" end item = args[0] name = args[1] # Create dependency current_item = @site.compiler.dependency_tracker.top if item != current_item Nanoc::NotificationCenter.post(:visit_started, item) Nanoc::NotificationCenter.post(:visit_ended, item) # This is an extremely ugly hack to get the compiler to recompile the # item from which we use content. For this, we need to manually edit # the content attribute to reset it. :( # FIXME clean this up if !@site.captures_store_compiled_items.include? item @site.captures_store_compiled_items << item item.forced_outdated = true item.reps.each do |r| raw_content = item.raw_content r.content = { :raw => raw_content, :last => raw_content } @site.compiler.send(:compile_rep, r) end end end # Get content @site.captures_store[item, name.to_sym] end end
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