hari

• Feb 3rd, 2012

 

i think , class variable i.e;static and instance variables i.e;non-static are there .but there is no class instance variable.

Satya

• Mar 11th, 2013

 

There is nothing called Class instance variables but there are Class variables that are shared by all the instances of a Class. Every Class variable is declared preceded by @@.

Code
class SomeClass


        @@no_of_instances = 0


        .....


        ...


        ..


end

karmue

 Profile Answers by karmue 

• Apr 1st, 2013

 

there's no class instance variable but there is instance variable and class variable, or global variable @variable is shared in the defined instance

@@variable is shared for all instances of this class
and also you need attr_accessor to enable access from outside

Nox

• Feb 25th, 2014

 

There is a thing called class instance variable. Since any Ruby class is in fact object, you can define instance variables for it. It is generally advised to use @class_instance_variable on a class instead of a @@class_variable, when you dont want class data to be shared with descendants.

Code
class BaseClass


  @class_instance_variable = :just_defined_a_class


  @@class_variable = :base_class


 


  def self.check_class_variables


    puts @class_instance_variable


    puts @@class_variable


  end


end


 


BaseClass.check_class_variables


#Prints


# just_defined_a_class


# base_class


 


class DescendantClass < BaseClass


  @class_instance_variable = :just_defined_descendant_class


  @@class_variable = :descendant_class


end


 


DescendantClass.check_class_variables


#just_defined_descendant_class


#descendant_class


 


#But 


BaseClass.check_class_variables


#just_defined_a_class


#descendant_class


 


 

Dwaraka

• Dec 18th, 2014

 

No. Please refer to answer given by Nox. When a variable is defined within the body of the class its called Class Instance Variable. It is like class variable but cannot be inherited. Usual use case is for setting up configuration files and is not unique for its subclasses.