module T::Props::WeakConstructor

def initialize(hash={})
  expected_keys = {}
  hash.each_key {|key| expected_keys[key] = true}
  decorator = self.class.decorator
  decorator.props.each do |p, rules|
    if hash.key?(p)
      expected_keys.delete(p)
      val = hash[p]
    elsif decorator.has_default?(rules)
      val = decorator.get_default(rules, self.class)
    else
      next
    end
    decorator.prop_set(self, p, val, rules)
  end
  unless expected_keys.empty?
    raise ArgumentError.new("#{@class}: Unrecognized properties in #with_props: #{expected_keys.keys.join(', ')}")
  end
end