instance_variable_set(p1, p2) public

Sets the instance variable named by symbol to the given object, thereby frustrating the efforts of the class’s author to attempt to provide proper encapsulation. The variable does not have to exist prior to this call. If the instance variable name is passed as a string, that string is converted to a symbol.

class Fred
  def initialize(p1, p2)
    @a, @b = p1, p2
  end
end
fred = Fred.new('cat', 99)
fred.instance_variable_set(:@a, 'dog')   #=> "dog"
fred.instance_variable_set(:@c, 'cat')   #=> "cat"
fred.inspect                             #=> "#<Fred:0x401b3da8 @a=\"dog\", @b=99, @c=\"cat\">"
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November 18, 2009 - (>= v1_8_6_287)
5 thanks

Example

code:

class Klass
  def set(string)
    var_name = "@#{string}"  # the '@' is required
    self.instance_variable_set(var_name, 'bar')
  end
  def puts_foo
    puts @foo
  end
end
k = Klass.new
k.puts_foo  # nil
k.set('foo')
k.puts_foo  # 'bar'