instance_variable.rb

class Person
	attr_accessor :name
	
	def set_name
	  @name = 'joe'
	end
	
	def dump_by_varibale
	  puts @name
	end
	
	def dump_by_reader
	  puts name
	end
end

a = Person.new
a.set_name
a.dump_by_varibale  #=> "joe"
a.dump_by_reader    #=> "joe"
puts a.name         #=> "joe"

# set by writer
a.name = "john"
a.dump_by_varibale  #=> "john"
a.dump_by_reader    #=> "john"
puts a.name         #=> "john"