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require 'active_support/core_ext/array/extract_options'
# Extends the class object with class and instance accessors for class attributes,
# just like the native attr* accessors for instance attributes.
#
# Note that unlike +class_attribute+, 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 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]
#
# class Female < Person
# end
#
# Female.hair_colors << :pink
# Female.hair_colors # => [:brown, :black, :blonde, :red, :pink]
# Female.new.hair_colors # => [:brown, :black, :blonde, :red, :pink]
# Person.hair_colors # => [:brown, :black, :blonde, :red, :pink]
#
# To opt out of the instance writer method, pass :instance_writer => false.
# To opt out of the instance reader method, pass :instance_reader => false.
# To opt out of both instance methods, pass :instance_accessor => false.
#
# class Person
# cattr_accessor :hair_colors, :instance_writer => false, :instance_reader => false
# end
#
# 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 any word character starting with a letter or underscore
# and without spaces.
#
# class Person
# cattr_reader :"1_Badname "
# end
# # => NameError: invalid attribute name
#
# If you want to opt out the instance writer method, 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|
raise NameError.new('invalid attribute name') unless sym =~ /^[_A-Za-z]\w*$/
class_eval(<<-EOS, __FILE__, __LINE__ + 1)
unless defined? @@#{sym}
@@#{sym} = nil
end
def self.#{sym}
@@#{sym}
end
EOS
unless options[:instance_reader] == false || options[:instance_accessor] == false
class_eval(<<-EOS, __FILE__, __LINE__ + 1)
def #{sym}
@@#{sym}
end
EOS
end
end
end
# Defines a class attribute if it's not defined and creates a writer method to allow
# assignment to the attribute.
#
# class Person
# cattr_writer :hair_colors
# end
#
# Person.hair_colors = [:brown, :black]
# Person.class_variable_get("@@hair_colors") # => [:brown, :black]
# Person.new.hair_colors = [:blonde, :red]
# Person.class_variable_get("@@hair_colors") # => [:blonde, :red]
#
# The attribute name must be any word character starting with a letter or underscore
# and without spaces.
#
# class Person
# cattr_writer :"1_Badname "
# end
# # => NameError: invalid attribute name
#
# If you want to opt out the instance writer method, pass <tt>instance_writer: false</tt>
# or <tt>instance_accessor: false</tt>.
#
# class Person
# cattr_writer :hair_colors, instance_writer: false
# end
#
# Person.new.hair_colors = [:blonde, :red] # => NoMethodError
#
# Also, you can pass a block to set up the attribute with a default value.
#
# class Person
# cattr_writer :hair_colors do
# [:brown, :black, :blonde, :red]
# end
# end
#
# Person.class_variable_get("@@hair_colors") # => [:brown, :black, :blonde, :red]
def cattr_writer(*syms)
options = syms.extract_options!
syms.each do |sym|
raise NameError.new('invalid attribute name') unless sym =~ /^[_A-Za-z]\w*$/
class_eval(<<-EOS, __FILE__, __LINE__ + 1)
unless defined? @@#{sym}
@@#{sym} = nil
end
def self.#{sym}=(obj)
@@#{sym} = obj
end
EOS
unless options[:instance_writer] == false || options[:instance_accessor] == false
class_eval(<<-EOS, __FILE__, __LINE__ + 1)
def #{sym}=(obj)
@@#{sym} = obj
end
EOS
end
send("#{sym}=", yield) if block_given?
end
end
# Defines 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)
end
end
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