vendor/rails/activesupport/lib/active_support/core_ext/module/attribute_accessors.rb

   1 # Extends the module object with module and instance accessors for class attributes,
   2 # just like the native attr* accessors for instance attributes.
   3 #
   4 #  module AppConfiguration
   5 #    mattr_accessor :google_api_key
   6 #    self.google_api_key = "123456789"
   7 #
   8 #    mattr_accessor :paypal_url
   9 #    self.paypal_url = "www.sandbox.paypal.com"
  10 #  end
  11 #
  12 #  AppConfiguration.google_api_key = "overriding the api key!"
  13 class Module
  14   def mattr_reader(*syms)
  15     syms.each do |sym|
  16       next if sym.is_a?(Hash)
  17       class_eval(<<-EOS, __FILE__, __LINE__)
  18         unless defined? @@#{sym}
  19           @@#{sym} = nil
  20         end
  21
  22         def self.#{sym}
  23           @@#{sym}
  24         end
  25
  26         def #{sym}
  27           @@#{sym}
  28         end
  29       EOS
  30     end
  31   end
  32
  33   def mattr_writer(*syms)
  34     options = syms.extract_options!
  35     syms.each do |sym|
  36       class_eval(<<-EOS, __FILE__, __LINE__)
  37         unless defined? @@#{sym}
  38           @@#{sym} = nil
  39         end
  40
  41         def self.#{sym}=(obj)
  42           @@#{sym} = obj
  43         end
  44
  45         #{"
  46         def #{sym}=(obj)
  47           @@#{sym} = obj
  48         end
  49         " unless options[:instance_writer] == false }
  50       EOS
  51     end
  52   end
  53
  54   def mattr_accessor(*syms)
  55     mattr_reader(*syms)
  56     mattr_writer(*syms)
  57   end
  58 end