require 'active_support/core_ext/object/blank'
module ActionView
# = Action View Capture Helper
module Helpers
# CaptureHelper exposes methods to let you extract generated markup which
# can be used in other parts of a template or layout file.
#
# It provides a method to capture blocks into variables through capture and
# a way to capture a block of markup for use in a layout through content_for.
module CaptureHelper
# The capture method allows you to extract part of a template into a
# variable. You can then use this variable anywhere in your templates or layout.
#
# ==== Examples
# The capture method can be used in ERb templates...
#
# <% @greeting = capture do %>
# Welcome to my shiny new web page! The date and time is
# <%= Time.now %>
# <% end %>
#
# ...and Builder (RXML) templates.
#
# @timestamp = capture do
# "The current timestamp is #{Time.now}."
# end
#
# You can then use that variable anywhere else. For example:
#
#
# <%= @greeting %>
#
# <%= @greeting %>
#
#
def capture(*args)
value = nil
buffer = with_output_buffer { value = yield(*args) }
if string = buffer.presence || value and string.is_a?(String)
NonConcattingString.new(string)
end
end
# Calling content_for stores a block of markup in an identifier for later use.
# You can make subsequent calls to the stored content in other templates, helper modules
# or the layout by passing the identifier as an argument to content_for.
#
# Note: yield can still be used to retrieve the stored content, but calling
# yield doesn't work in helper modules, while content_for does.
#
# ==== Examples
#
# <% content_for :not_authorized do %>
# alert('You are not authorized to do that!')
# <% end %>
#
# You can then use content_for :not_authorized anywhere in your templates.
#
# <%= content_for :not_authorized if current_user.nil? %>
#
# This is equivalent to:
#
# <%= yield :not_authorized if current_user.nil? %>
#
# content_for, however, can also be used in helper modules.
#
# module StorageHelper
# def stored_content
# content_for(:storage) || "Your storage is empty"
# end
# end
#
# This helper works just like normal helpers.
#
# <%= stored_content %>
#
# You can use the yield syntax alongside an existing call to yield in a layout. For example:
#
# <%# This is the layout %>
#
#
# My Website
# <%= yield :script %>
#
#
# <%= yield %>
#
#
#
# And now, we'll create a view that has a content_for call that
# creates the script identifier.
#
# <%# This is our view %>
# Please login!
#
# <% content_for :script do %>
#
# <% end %>
#
# Then, in another view, you could to do something like this:
#
# <%= link_to 'Logout', :action => 'logout', :remote => true %>
#
# <% content_for :script do %>
# <%= javascript_include_tag :defaults %>
# <% end %>
#
# That will place