Crystal Monomorphism example code

monomorphism_proxy.cr

abstract class Parent #同じシグネチャなので、abstractを通して、制約をつける
  abstract def disp
end

class A < Parent
  def disp : String
    "call A"
  end
end

class B < Parent
  def disp : String
    "call B"
  end
end


module Switcher
  def self.new(type : Symbol) : Parent   
    if type == :A
      A.new
    elsif type == :B
      B.new
    else
      raise "Not found symbol"
    end
  end
end

puts Switcher.new(:A).disp
puts Switcher.new(:B).disp