IRB vs ruby-doc.org

rubyonrails-talk
1

The ruby documentation says instance_variable_set is a public instance method of Object:

And I believe it because you can call it on instances of Object:

1.9.3p0 :005 > Object.new.instance_variable_set :@a, 1 => 1

It can't be a public instance method of Class or Module, because otherwise the Object instance wouldnt have access to it, since the above Object instance is an instance of Object, whose superclass is BasicObject and that's it.

So my question is why when I launch IRB in Rails 3/Ruby 1.9.3, and return as an array the instance methods of Object, instance_variable_set is no where to be found:

1.9.3p0 :001 > Object.instance_methods(false) => [:psych_to_yaml, :to_yaml_properties, :to_yaml, :in?, :blank?, :present?, :presence, :acts_like?, :try, :html_safe?, :duplicable?, :to_param, :to_query, :`, :instance_values, :instance_variable_names, :to_json, :with_options, :as_json]

Shouldn't instance_variable_set be listed here?

2

Object includes the Kernel module, which defines the :instance_variable_set method

1.9.3p194 :001 > Kernel.instance_methods(false).include? :instance_variable_set

=> true

1.9.3p194 :002 > Object.is_a? Kernel

=> true