simple subtype seq example

simple_subtype.nim

type
  Person = ref object of RootObj
    name*: string  # the * means that `name` is accessible from other modules
    age: int       # no * means that the field is hidden from other modules
  
  Student = ref object of Person # Student inherits from Person
    id: int                      # with an id field

var
  student: Student
  person: Person

# object construction:
student = Student(name: "Anton", age: 5, id: 2)

var school : seq[Person] = @[]

school.add(student)

echo school[0][]