From: Suman Gurung <sumangurung@...>
Date: 2009-01-02T02:46:51+09:00
Subject: Re: How do I pass the name of an instance variable into an object?

i just tried putting everything together and it worked great.
I thought i will share the consolidated code, so here it is:

class SomeClass
  def initialize
    @first = 'first variable'
    @second = 'second variable'
  end

  def print_instance_variable(*args)
    args.each do |arg|
      begin
        raise unless instance_variable_defined?("@#{arg}")
        puts self.instance_variable_get("@#{arg}")
      rescue => ex
        puts  "#{ex.class}: #{ex.message}"
      end
    end
  end

  def add_instance_variable(name, initial_value)
    raise if instance_variable_defined?("@#{name}")
    self.instance_variable_set("@#{name}", "#{initial_value}")
  end
end


x = SomeClass.new
x.print_instance_variable(:first)
x.print_instance_variable(:second)

puts "\n****************** printing both values in one method call
*************"
x.print_instance_variable :first, :second

puts "\n*************** should throw an exception, because the
instance variable is undefined **************"
x.print_instance_variable :third


x.add_instance_variable(:third, "third value")

puts "\n*************** should print the third instance variable**************"
x.print_instance_variable :third