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Add documentation, and also add tests for appropriate init-field behavior.

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svn: r18541
This commit is contained in:
Stevie Strickland 2010-03-15 08:47:09 +00:00
parent 924842d9e9
commit c7c8f7061e
2 changed files with 46 additions and 1 deletions
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11
collects/scribblings/reference/class.scrbl
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@ -1476,13 +1476,15 @@ resulting trait is the same as for @scheme[trait-sum], otherwise the
@section{Object and Class Contracts}
@defform/subs[
#:literals (field inherit inherit-field super inner override augment augride)
#:literals (field init init-field inherit inherit-field super inner override augment augride)
(class/c member-spec ...)
([member-spec
method-spec
(field field-spec ...)
(init field-spec ...)
(init-field field-spec ...)
(inherit method-spec ...)
(inherit-field field-spec ...)
(super method-spec ...)
@ -1525,6 +1527,13 @@ The external contracts are as follows:
value contained in that field when accessed via an object of that class. Since
fields may be mutated, these contracts are checked on any external access and/or
mutation of the field.}
@item{An initialization argument contract, tagged with @scheme[init], describes the
expected behavior of the value paired with that name during class instantiation.
The same name can be provided more than once, in which case the first such contract
in the @scheme[class/c] form is applied to the first value tagged with that name in
the list of initialization arguments, and so on.}
@item{The contracts listed in an @scheme[init-field] section are treated as if each
contract appeared in an @scheme[init] section and a @scheme[field] section.}
]
The internal contracts are as follows:

36
collects/tests/mzscheme/contract-test.ss
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@ -4717,6 +4717,42 @@
[d%/c (contract (class/c (init [a integer?] [a string?])) d% 'pos 'neg)]
[d%/c/c (contract (class/c (init [a number?])) d%/c 'pos 'neg)])
(new d%/c/c [a #t] [a "foo"])))
(test/spec-passed
'class/c-higher-order-init-field-1
'(let ([c% (contract (class/c (init-field [f (-> number? number?)]))
(class object% (super-new) (init-field f) (f 3))
'pos
'neg)])
(new c% [f (lambda (x) x)])))
(test/pos-blame
'class/c-higher-order-init-field-2
'(let ([c% (contract (class/c (init-field [f (-> number? number?)]))
(class object% (super-new) (init-field f) (f #t))
'pos
'neg)])
(new c% [f (lambda (x) x)])))
(test/neg-blame
'class/c-higher-order-init-field-3
'(let ([c% (contract (class/c (init-field [f (-> number? number?)]))
(class object% (super-new) (init-field f) (f 3))
'pos
'neg)])
(new c% [f (lambda (x) (zero? x))])))
;; Make sure that the original provider of the value is blamed if an
;; init arg is given an invalid value, and then that is retrieved by
;; an external client.
(test/neg-blame
'class/c-higher-order-init-field-4
'(let* ([c% (contract (class/c (init-field [f (-> number? number?)]))
(class object% (super-new) (init-field f))
'pos
'neg)]
[o (new c% [f (lambda (x) (zero? x))])])
((get-field f o) 3)))
(test/spec-passed
'class/c-higher-order-method-1