Access `self` of an object through the parameters

Question

Let\'s say I want to access an element of an array at a random index this way:

[1, 2, 3, 4].at(rand(4))

Is there a way to pass the size of

Answer 1

You can use instance_eval to execute ruby code with the binding of the array variable

[1, 2, 3, 4].instance_eval { at(rand(size)) }

Assuming you are interested in a random element as Array#at returns an element at given index, you can use Array#sample to pick a random element from an array.

[1,2,3,4].sample
#=> 3

If you do not want to use instance_eval (or any form of eval), then, you can add a method to Array class by monkey patching - generally speaking, I am not sure whether it's a wise idea to monkey patch though

class Array
  def random_index
    rand(size)
  end
end

["a","b","c","d"].random_index
#=> 2