Injecting method arguments

demo.rb

i = Injector.new first: 'First Name', last: 'Last Name', power: 2

def full_name(first, last)
  "#{first} #{last}"
end

def random_to_power(power)
  4 ** power
end

p i.call method(:full_name) # => "First Name Last Name"
p i.call method(:random_to_power) # => 16

injector.rb

class Injector
  def initialize(mappings)
    @mappings = mappings
  end
  
  def params(meth)
    meth.parameters.map { |(type, name)| name }
  end
  
  def args(meth)
    [].tap do |a|
      params(meth).each do |p|
        a << @mappings[p]
      end
    end
  end
  
  def call(meth)
    meth.call *args(meth)
  end
end