A safety container for you, it is as handy as Struct(+).

# url
https://github.com/kachick/striuct
https://rubygems.org/gems/striuct

# ex

class User < Striuct.new
member :id, Integer
member :age, (20..140)
member :name, /\A\w+\z/, /\A\w+ \w+\z/
end

# pass
user = User.new 128381, 20

# pass
user.age = 30
user[2] = 'foo bar'

# fail
user[:id] = 10.0
user.age = 19
user[2] = nil

# and more