The implementation below is very handy when you are you are not really concerned about a number or a quality of arguments you are setting (maybe you are prototyping ? consuming 3rd party API ?)
Pretty Straightforward, here is the code :

class MPB
  def initialize(*args)
    args[0].each do |key,value|
      singleton_class.class_eval { attr_accessor "#{key}" }
      eval("@#{key} = "#{value}"")
     # alternatively you can use this helper:  instance_variable_set("@#{key}", value) 
    end
  end
end

mpb = MPB.new(author: 'Anatoly', title: 'How to dynamically initialize args',body: "Read More!")

p mpb
# => #<MPB:0x00007f81fc0af250 @author="Anatoly", @title="How to dynamically initialize args", @body="Read More!">

Quick Explanation what  am I doing here:

initialize() allows us to receive *args, which fives us a  Hash from arguments that you are passing to it. I go through this hash and create instance variable of every hash key, then I assign value to this hash key. Totally dynamic. I also create attribute_accessor on a fly so I could read and write to any of those instance variables.

Note: There are edge cases not covered here, do make sure it works for your particular situation, but I think this is a good start.

Cheers,

Anatoly

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