class variables

declaring_class_variables.rb

class SomeClassVariables

  @@class_level_var = "class_level_var"
   
  def self.add_class_var
    @@class_method_var = "class_method_var"
  end

  def self.show_class_var
    puts @@class_level_var
    puts @@class_method_var if defined? @@class_method_var
    puts @@init_set_var if defined? @@init_set_var
    puts @@instance_set_var if defined? @@instance_set_var
  end

  def initialize
    @@init_set_var = "init_set_var"
  end 

  def set_var
    @@instance_set_var = "instance_set_var"
  end
end

puts SomeClassVariables.class_variables
SomeClassVariables.show_class_var
puts

SomeClassVariables.add_class_var
puts SomeClassVariables.class_variables
SomeClassVariables.show_class_var
puts

SomeClassVariables.new
puts SomeClassVariables.class_variables
SomeClassVariables.show_class_var
puts
 
SomeClassVariables.new.set_var
puts SomeClassVariables.class_variables
SomeClassVariables.show_class_var
puts