vendor/rails/actionmailer/lib/action_mailer/helpers.rb

   1 require 'active_support/dependencies'
   2
   3 module ActionMailer
   4   module Helpers #:nodoc:
   5     def self.included(base) #:nodoc:
   6       # Initialize the base module to aggregate its helpers.
   7       base.class_inheritable_accessor :master_helper_module
   8       base.master_helper_module = Module.new
   9
  10       # Extend base with class methods to declare helpers.
  11       base.extend(ClassMethods)
  12
  13       base.class_eval do
  14         # Wrap inherited to create a new master helper module for subclasses.
  15         class << self
  16           alias_method_chain :inherited, :helper
  17         end
  18
  19         # Wrap initialize_template_class to extend new template class
  20         # instances with the master helper module.
  21         alias_method_chain :initialize_template_class, :helper
  22       end
  23     end
  24
  25     module ClassMethods
  26       # Makes all the (instance) methods in the helper module available to templates rendered through this controller.
  27       # See ActionView::Helpers (link:classes/ActionView/Helpers.html) for more about making your own helper modules
  28       # available to the templates.
  29       def add_template_helper(helper_module) #:nodoc:
  30         master_helper_module.module_eval "include #{helper_module}"
  31       end
  32
  33       # Declare a helper:
  34       #   helper :foo
  35       # requires 'foo_helper' and includes FooHelper in the template class.
  36       #   helper FooHelper
  37       # includes FooHelper in the template class.
  38       #   helper { def foo() "#{bar} is the very best" end }
  39       # evaluates the block in the template class, adding method +foo+.
  40       #   helper(:three, BlindHelper) { def mice() 'mice' end }
  41       # does all three.
  42       def helper(*args, &block)
  43         args.flatten.each do |arg|
  44           case arg
  45             when Module
  46               add_template_helper(arg)
  47             when String, Symbol
  48               file_name  = arg.to_s.underscore + '_helper'
  49               class_name = file_name.camelize
  50
  51               begin
  52                 require_dependency(file_name)
  53               rescue LoadError => load_error
  54                 requiree = / -- (.*?)(\.rb)?$/.match(load_error.message).to_a[1]
  55                 msg = (requiree == file_name) ? "Missing helper file helpers/#{file_name}.rb" : "Can't load file: #{requiree}"
  56                 raise LoadError.new(msg).copy_blame!(load_error)
  57               end
  58
  59               add_template_helper(class_name.constantize)
  60             else
  61               raise ArgumentError, 'helper expects String, Symbol, or Module argument'
  62           end
  63         end
  64
  65         # Evaluate block in template class if given.
  66         master_helper_module.module_eval(&block) if block_given?
  67       end
  68
  69       # Declare a controller method as a helper.  For example,
  70       #   helper_method :link_to
  71       #   def link_to(name, options) ... end
  72       # makes the link_to controller method available in the view.
  73       def helper_method(*methods)
  74         methods.flatten.each do |method|
  75           master_helper_module.module_eval <<-end_eval
  76             def #{method}(*args, &block)
  77               controller.__send__(%(#{method}), *args, &block)
  78             end
  79           end_eval
  80         end
  81       end
  82
  83       # Declare a controller attribute as a helper.  For example,
  84       #   helper_attr :name
  85       #   attr_accessor :name
  86       # makes the name and name= controller methods available in the view.
  87       # The is a convenience wrapper for helper_method.
  88       def helper_attr(*attrs)
  89         attrs.flatten.each { |attr| helper_method(attr, "#{attr}=") }
  90       end
  91
  92       private
  93         def inherited_with_helper(child)
  94           inherited_without_helper(child)
  95           begin
  96             child.master_helper_module = Module.new
  97             child.master_helper_module.__send__(:include, master_helper_module)
  98             child.helper child.name.to_s.underscore
  99           rescue MissingSourceFile => e
 100             raise unless e.is_missing?("helpers/#{child.name.to_s.underscore}_helper")
 101           end
 102         end
 103     end
 104
 105     private
 106       # Extend the template class instance with our controller's helper module.
 107       def initialize_template_class_with_helper(assigns)
 108         returning(template = initialize_template_class_without_helper(assigns)) do
 109           template.extend self.class.master_helper_module
 110         end
 111       end
 112   end
 113 end