s c h e m a t i c s : c o o k b o o k

(module test-default-fields mzscheme
  (require (lib "class.ss"))
  (provide (all-defined))
  (define adder%
    (class object%
      (super-new)
      (init-field [increment 1])
      
      (define/public (add x)
        (+ increment x)))))

> (send (new adder%) add 3)
4

> (send (new adder% [increment 42]) add 3)
45

  (define person%
    (class object%
      (super-new)

      (init [name "John Doe"])
      (field [-name (regexp-replace* "[^a-zA-Z]" name "")])
      
      (define/public (say-hello)
        (printf "hi, my name is ~a~n" -name))))

> (send (new person%) say-hello)
hi, my name is JohnDoe
> (send (new person% [name "f**b*r"]) say-hello)
hi, my name is fbr