Today, I accidentally discovered the mysterious Data class in Ruby, and I can’t find any useful information upon what it does, or why it’s there. I assume it’s part of the language implementation itself.
Does anybody know what it does?
mbp-scott:~ scott$ irb
ruby-1.9.3-p0 :001 > Data
=> Data
ruby-1.9.3-p0 :002 > Data.is_a? Module
=> true
ruby-1.9.3-p0 :003 > Data.is_a? Class
=> true
ruby-1.9.3-p0 :004 > Data.ancestors
=> [Data, Object, Kernel, BasicObject]
ruby-1.9.3-p0 :005 > Data.methods
=> [:allocate, :new, :superclass, :freeze, :===, :==, :<=>, :<, :<=, :>,
:>=, :to_s,:included_modules, :include?, :name, :ancestors, :instance_methods,
:public_instance_methods, :protected_instance_methods, :private_instance_methods,
:constants, :const_get, :const_set, :const_defined?, :const_missing, :class_variables,
:remove_class_variable, :class_variable_get, :class_variable_set,
:class_variable_defined?, :public_constant, :private_constant, :module_exec,
:class_exec, :module_eval, :class_eval, :method_defined?, :public_method_defined?,
:private_method_defined?, :protected_method_defined?, :public_class_method
:private_class_method, :autoload, :autoload?, :instance_method, :public_instance_method,
:nil?, :=~, :!~, :eql?, :hash, :class, :singleton_class, :clone, :dup, :initialize_dup,
:initialize_clone, :taint, :tainted?, :untaint, :untrust, :untrusted?, :trust, :frozen?,
:inspect, :methods, :singleton_methods, :protected_methods, :private_methods,
:public_methods, :instance_variables, :instance_variable_get, :instance_variable_set,
:instance_variable_defined?, :instance_of?, :kind_of?, :is_a?, :tap, :send,
:public_send, :respond_to?, :respond_to_missing?, :extend, :display, :method,
:public_method, :define_singleton_method, :object_id, :to_enum, :enum_for, :equal?,
:!, :!=, :instance_eval, :instance_exec, :__send__, :__id__]
ruby-1.9.3-p0 :006 > Data.instance_variables
=> []
ruby-1.9.3-p0 :007 > self
=> main
Might be connected to the C data type RUBY_T_DATA. Which might be a way to store C data via the C API in the Ruby VM.