Merge pull request #6211 from frodsan/docs_attr_accessor_32stable

Adding docs to attribute accessor methods.

activesupport/lib/active_support/core_ext/class/attribute_accessors.rb

@@ -26,6 +26,32 @@
 #   Person.new.hair_colors = [:brown]  # => NoMethodError
 #   Person.new.hair_colors             # => NoMethodError
 class Class
+  # Defines a class attribute if it's not defined and creates a reader method that
+  # returns the attribute value.
+  #
+  #   class Person
+  #     cattr_reader :hair_colors
+  #   end
+  #
+  #   Person.class_variable_set("@@hair_colors", [:brown, :black])
+  #   Person.hair_colors     # => [:brown, :black]
+  #   Person.new.hair_colors # => [:brown, :black]
+  #
+  # The attribute name must be a valid method name in Ruby.
+  #
+  #   class Person
+  #     cattr_reader :"1_Badname "
+  #   end
+  #   # => NameError: invalid attribute name
+  #
+  # If you want to opt out the instance reader method, you can pass <tt>instance_reader: false</tt>
+  # or <tt>instance_accessor: false</tt>.
+  #
+  #   class Person
+  #     cattr_reader :hair_colors, instance_reader: false
+  #   end
+  #
+  #   Person.new.hair_colors # => NoMethodError
   def cattr_reader(*syms)
     options = syms.extract_options!
     syms.each do |sym|
@@ -49,6 +75,43 @@ def #{sym}
     end
   end
 
+  # Defines a class attribute if it's not defined and creates a writer method to allow
+  # assignment to the attribute.
+  #
+  #   class Person
+  #     cattr_writer :hair_colors
+  #   end
+  #
+  #   Person.hair_colors = [:brown, :black]
+  #   Person.class_variable_get("@@hair_colors") # => [:brown, :black]
+  #   Person.new.hair_colors = [:blonde, :red]
+  #   Person.class_variable_get("@@hair_colors") # => [:blonde, :red]
+  #
+  # The attribute name must be a valid method name in Ruby.
+  #
+  #   class Person
+  #     cattr_writer :"1_Badname "
+  #   end
+  #   # => NameError: invalid attribute name
+  #
+  # If you want to opt out the instance writer method, pass <tt>instance_writer: false</tt>
+  # or <tt>instance_accessor: false</tt>.
+  #
+  #   class Person
+  #     cattr_writer :hair_colors, instance_writer: false
+  #   end
+  #
+  #   Person.new.hair_colors = [:blonde, :red] # => NoMethodError
+  #
+  # Also, you can pass a block to set up the attribute with a default value.
+  #
+  #   class Person
+  #     cattr_writer :hair_colors do
+  #       [:brown, :black, :blonde, :red]
+  #     end
+  #   end
+  #
+  #   Person.class_variable_get("@@hair_colors") # => [:brown, :black, :blonde, :red]
   def cattr_writer(*syms)
     options = syms.extract_options!
     syms.each do |sym|
@@ -73,6 +136,54 @@ def #{sym}=(obj)
     end
   end
 
+  # Defines both class and instance accessors for class attributes.
+  #
+  #   class Person
+  #     cattr_accessor :hair_colors
+  #   end
+  #
+  #   Person.hair_colors = [:brown, :black, :blonde, :red]
+  #   Person.hair_colors     # => [:brown, :black, :blonde, :red]
+  #   Person.new.hair_colors # => [:brown, :black, :blonde, :red]
+  #
+  # If a subclass changes the value then that would also change the value for
+  # parent class. Similarly if parent class changes the value then that would
+  # change the value of subclasses too.
+  #
+  #   class Male < Person
+  #   end
+  #
+  #   Male.hair_colors << :blue
+  #   Person.hair_colors # => [:brown, :black, :blonde, :red, :blue]
+  #
+  # To opt out of the instance writer method, pass <tt>instance_writer: false</tt>.
+  # To opt out of the instance reader method, pass <tt>instance_reader: false</tt>.
+  #
+  #   class Person
+  #     cattr_accessor :hair_colors, instance_writer: false, instance_reader: false
+  #   end
+  #
+  #   Person.new.hair_colors = [:brown]  # => NoMethodError
+  #   Person.new.hair_colors             # => NoMethodError
+  #
+  # Or pass <tt>instance_accessor: false</tt>, to opt out both instance methods.
+  #
+  #   class Person
+  #     cattr_accessor :hair_colors, instance_accessor: false
+  #   end
+  #
+  #   Person.new.hair_colors = [:brown]  # => NoMethodError
+  #   Person.new.hair_colors             # => NoMethodError
+  #
+  # Also you can pass a block to set up the attribute with a default value.
+  #
+  #   class Person
+  #     cattr_accessor :hair_colors do
+  #       [:brown, :black, :blonde, :red]
+  #     end
+  #   end
+  #
+  #   Person.class_variable_get("@@hair_colors") #=> [:brown, :black, :blonde, :red]
   def cattr_accessor(*syms, &blk)
     cattr_reader(*syms)
     cattr_writer(*syms, &blk)