CODEWITHSUNDEEP
rubysingleton
Kyle Decot
Kyle Decot

Reputation: 20815

Ruby Singleton Attribute Defaults

I'm attempting to create a class that uses the Singleton module:

class Foo
  include Singleton

  # def initialize
  #   puts "Initialized!"
  # end  

  singleton_class.class_eval do
    attr_accessor :bar
  end
end

The problem here is that bar does not have a default/initial value. I've added a initialize method to my class in hopes that it would be invoked once but this doesn't seem to be the case. What is the proper way to ensure that bar has a value when this class is loaded?

Upvotes: 1

Views: 651

Answers (1)

toro2k
toro2k

Reputation: 19228

As you implemented it the accessors for @bar are methods of the class Foo, thus you have define @bar as a class instance variable of Foo, not of the instance of Foo:

class Foo
  include Singleton
  @bar = 0
  singleton_class.class_eval do
    attr_accessor :bar
  end
end

Foo.bar
# => 0

Upvotes: 3

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