▼Scheme Utilities in (planet cce/ scheme: 6: 0)
►6 Classes and Objects
On this page:
6.1 Predicates and Contracts
class-or-interface/ c
object-provides/ c
class-provides/ c
mixin-provides/ c
object/ c
class/ c
mixin/ c
6.2 Mixins
ensure-interface
6.3 Methods
send+
send-each
  ← prev  up  next → 

6 Classes and Objects

 (require (planet cce/scheme:6:0/class))

This module provides tools for classes, objects, and mixins.

6.1 Predicates and Contracts

class-or-interface/c : flat-contract?
Recognizes classes and interfaces.

(object-provides/c spec ...) → flat-contract?
  spec : class-or-interface/c
Recognizes objects which are instances of all the given classes and interfaces.

(class-provides/c spec ...) → flat-contract?
  spec : class-or-interface/c
Recognizes classes which are subclasses (not strictly) and implementations, respectively, of all the given classes and interfaces.

(mixin-provides/c [super-expr ...] [sub-expr ...])
Function contract for a mixin whose argument is the parent class c% matching (class-provides/c super-expr ...) and whose result matches (class-provides/c c% sub-expr ...).

(object/c spec ...) → flat-contract?
  spec : class-or-interface/c
(class/c spec ...) → flat-contract?
  spec : class-or-interface/c
(mixin/c [super-expr ...] [arg-expr ...] [sub-expr ...])
Deprecated: These forms have been renamed to object-provides/c, class-provides/c, and mixin-provides/c above to make room for more expressive class, object, and mixin contracts that may be developed in scheme/class using the simpler names.

The middle clause of mixin/c has been removed in mixin-provides/c because mixins rarely need extra arguments, and class initialization arguments are usually the best way to provide them.

6.2 Mixins

(ensure-interface i<%> mx c%) → (class-provides/c c% i<%>)
  i<%> : interface?
  mx : (mixin-provides/c [] [i<%>])
  c% : class?
Returns c% if it implements i<%>; otherwise, returns (mx c%).

6.3 Methods

(send+ obj [message arg ...] ...)
Sends each message (with arguments) to obj, then returns obj.

Examples:

  (define c%
    (class object%
      (super-new)
      (define/public (say msg) (printf "~a!\n" msg))))
  > (send+ (new c%) [say 'Hello] [say 'Good-bye])

  Hello!

  Good-bye!

  #(struct:object:c% ...)

(send-each objs message arg ...)
Sends the message to each object in the list objs, returning (void).

Examples:

  (define c%
    (class object%
      (super-new)
      (init-field msg)
      (define/public (say to) (printf "~a, ~a!\n" msg to))))
  > (send-each
     (list (new c% [msg 'Hello])
           (new c% [msg 'Good-bye]))
     say 'World)

  Hello, World!

  Good-bye, World!

  ← prev  up  next →