vendor/rails/activesupport/lib/active_support/core_ext/object/instance_variables.rb

   1 class Object
   2   # Available in 1.8.6 and later.
   3   unless respond_to?(:instance_variable_defined?)
   4     def instance_variable_defined?(variable)
   5       instance_variables.include?(variable.to_s)
   6     end
   7   end
   8
   9   # Returns a hash that maps instance variable names without "@" to their
  10   # corresponding values. Keys are strings both in Ruby 1.8 and 1.9.
  11   #
  12   #   class C
  13   #     def initialize(x, y)
  14   #       @x, @y = x, y
  15   #     end
  16   #   end
  17   #
  18   #   C.new(0, 1).instance_values # => {"x" => 0, "y" => 1}
  19   def instance_values #:nodoc:
  20     instance_variables.inject({}) do |values, name|
  21       values[name.to_s[1..-1]] = instance_variable_get(name)
  22       values
  23     end
  24   end
  25
  26   # Returns an array of instance variable names including "@". They are strings
  27   # both in Ruby 1.8 and 1.9.
  28   #
  29   #   class C
  30   #     def initialize(x, y)
  31   #       @x, @y = x, y
  32   #     end
  33   #   end
  34   #
  35   #   C.new(0, 1).instance_variable_names # => ["@y", "@x"]
  36   if RUBY_VERSION >= '1.9'
  37     def instance_variable_names
  38       instance_variables.map { |var| var.to_s }
  39     end
  40   else
  41     alias_method :instance_variable_names, :instance_variables
  42   end
  43
  44   # Copies the instance variables of +object+ into +self+.
  45   #
  46   # Instance variable names in the +exclude+ array are ignored. If +object+
  47   # responds to <tt>protected_instance_variables</tt> the ones returned are
  48   # also ignored. For example, Rails controllers implement that method.
  49   #
  50   # In both cases strings and symbols are understood, and they have to include
  51   # the at sign.
  52   #
  53   #   class C
  54   #     def initialize(x, y, z)
  55   #       @x, @y, @z = x, y, z
  56   #     end
  57   #
  58   #     def protected_instance_variables
  59   #       %w(@z)
  60   #     end
  61   #   end
  62   #
  63   #   a = C.new(0, 1, 2)
  64   #   b = C.new(3, 4, 5)
  65   #
  66   #   a.copy_instance_variables_from(b, [:@y])
  67   #   # a is now: @x = 3, @y = 1, @z = 2
  68   def copy_instance_variables_from(object, exclude = []) #:nodoc:
  69     exclude += object.protected_instance_variables if object.respond_to? :protected_instance_variables
  70
  71     vars = object.instance_variables.map(&:to_s) - exclude.map(&:to_s)
  72     vars.each { |name| instance_variable_set(name, object.instance_variable_get(name)) }
  73   end
  74 end