method

attr_accessor_with_default

Ruby on Rails latest stable (v7.1.3.2) - 2 notes - Class: Module

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What's this?

Method deprecated or moved

This method is deprecated or moved on the latest stable version. The last existing version (v3.1.0) is shown here.

attr_accessor_with_default(sym, default = Proc.new) public

Declare an attribute accessor with an initial default return value.

To give attribute :age the initial value 25:

class Person
  attr_accessor_with_default :age, 25
end

person = Person.new
person.age # => 25

person.age = 26
person.age # => 26

To give attribute :element_name a dynamic default value, evaluated in scope of self:

attr_accessor_with_default(:element_name) { name.underscore }

Show source

# File activesupport/lib/active_support/core_ext/module/attr_accessor_with_default.rb, line 21
  def attr_accessor_with_default(sym, default = Proc.new)
    ActiveSupport::Deprecation.warn "attr_accessor_with_default is deprecated. Use Ruby instead!"
    define_method(sym, block_given? ? default : Proc.new { default })
    module_eval(      def #{sym}=(value)                          # def age=(value)        class << self; attr_accessor :#{sym} end  #   class << self; attr_accessor :age end        @#{sym} = value                           #   @age = value      end                                         # end, __FILE__, __LINE__ + 1)
  end

September 13, 2011

1 thank

Some unexpected behaviour

When using Array as default value, it behaves more like cattr_accessor…

class A
 attr_accessor_with_default :b, []
end

x = A.new
x.b << 1

#puts x.b.inspect => [1]

y = A.new
y.b << 2

#puts y.b.inspect => [1, 2]

October 10, 2011 - (>= v3.1.0)

1 thank

Use Ruby instead!

E.g.

class TestClass < SomeSuperClass
  attr_accessor :sample_acc

  def initialize      
    @sample_acc = []
    super
  end
end

If nil is not a valid value for this accessor, then you can just define reader for it.

class TestClass
  attr_accessor :sample_acc

  def sample_acc
    @sample_acc ||= 98
  end
end

attr_accessor_with_default

Related methods

Method deprecated or moved

Some unexpected behaviour

Use Ruby instead!