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fixes docs, closes #3682

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This commit is contained in:
Matthias Felleisen 2021-02-11 16:26:48 -05:00
parent c07e9cde09
commit 2ca6f7a5d6
1 changed files with 22 additions and 13 deletions
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37
pkgs/racket-doc/scribblings/reference/class.scrbl
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@ -1964,21 +1964,30 @@ As with the external contracts, when a method or field name is specified
@examples[#:eval class-eval
(eval:no-prompt
(define/contract woody2+c%
(class/c (super [draw (->m symbol? string?)]))
(class woody%
(define/override draw
(case-lambda
[(a) (super draw a)]
[(a b) (string-append (super draw a)
" and "
(super draw b))]))
(super-new))))
(send (new woody2+c%) draw 'evil-dr-porkchop 'zurg)
(send (new woody2+c%) draw "evil dr porkchop" "zurg")]
The last call signals an error blaming @racket[woody2%] because
there is no contract checking the initial @racket[draw] call.
(define/contract woody%+s
(class/c (super [draw (->m symbol? string?)]))
(class object%
(define/public (draw who)
(format "reach for the sky, ~a" who))
(super-new)))
(define woody2+c%
(class woody%+s
(define/override draw
(case-lambda
[(a) (super draw a)]
[(a b) (string-append (super draw a)
" and "
(super draw b))]))
(super-new))))
(send (new woody2+c%) draw 'evil-dr-porkchop 'zurg)
(eval:error (send (new woody2+c%) draw "evil dr porkchop" "zurg"))]
The last call signals an error blaming @racket[woody2%+c] because
there is no contract checking the initial @racket[draw] call and
the super-call violates its contract.
}
@item{A method contract tagged with @racket[inner] describes the
behavior the class expects of an augmenting method in a subclass.