class-level-wrapper.cr

struct Wrapper(T)
  module Interface
    abstract def unwrap
  end

  include Interface

  def unwrap
    T
  end
end

module Action
  abstract def call
end

class Foo
  include Action
  
  def call
    puts "Foo!"
  end
end

class Bar
  include Action
  
  def call
    puts "Bar!"
  end
end

ary = [] of Wrapper::Interface
ary << Wrapper(Bar).new
ary << Wrapper(Foo).new

ary.each do |item|
  klass = item.unwrap
  instance = klass.new
  instance.call
end