Using typeof with instance methods in Crystal

instance_typeof.cr

require "json"

class Container(T)
  getter value : T

  def initialize(@value)
  end
end

def new_container(json : String, t_class : T.class) : T forall T
  value = typeof(T.allocate.value).from_json(json)
  T.new(value)
end

alias Int32Container = Container(Int32)

container = new_container("123", Int32Container)

puts container.inspect