is it appropriate in a class, for a getter method of an instance variable which happens to be an array, to dup the variable so that such things as getter#push cannot be called on them?

andy.rb

class Andy
  def initialize
    @andytest = []
  end
  
  attr_reader :andytest
end

__END__

irb(main):017:0> x=Andy.new
=> #<Andy:0x007f25fec58b38 @andytest=[]>
irb(main):018:0> x.andytest
=> []
irb(main):019:0> x.andytest.push 1
=> [1]
irb(main):020:0> x
=> #<Andy:0x007f25fec58b38 @andytest=[1]>

andy2_revised.rb

class Andy
  def initialize
    @andytest = []
  end
  
  def andytest
    @andytest.dup
  end
end

__END__

irb(main):013:0* x=Andy.new
=> #<Andy:0x007f0249208918 @andytest=[]>
irb(main):014:0> x.andytest
=> []
irb(main):015:0> x.andytest.push 1
=> [1]
irb(main):016:0> x
=> #<Andy:0x007f0249208918 @andytest=[]>