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fix doc mistakes related to struct guards

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svn: r11368
This commit is contained in:
Matthew Flatt 2008-08-21 17:02:50 +00:00
parent c2e9a78ea9
commit e507d9a1a3
2 changed files with 20 additions and 15 deletions
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31
collects/scribblings/guide/define-struct.scrbl
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@ -406,13 +406,16 @@ A @scheme[_struct-option] always starts with a keyword:
@;-- FIXME:
@;-- Explain when to use guards instead of contracts, and vice-versa
@specspecsubform[(code:line #:guard guard-expr)]{
Specifies a @deftech{constructor guard} procedure to be called
whenever an instance of the structure type is created. The guard
takes as many arguments as non-automatic fields in the structure
type, and it should return the same number of values. The guard can
raise an exception if one of the given arguments is unacceptable, or
it can convert an argument.
@specspecsubform[(code:line #:guard guard-expr)]{ Specifies a
@deftech{constructor guard} procedure to be called whenever an
instance of the structure type is created. The guard takes as many
arguments as non-automatic fields in the structure type, plus one
more for the name of the instantiated type (in case a sub-type is
instantiated, in which case it's best to report an error using the
sub-type's name). The guard should return the same number of values
as given, minus the name argument. The guard can raise an exception
if one of the given arguments is unacceptable, or it can convert an
argument.
@defexamples[
#:eval posn-eval
@ -421,12 +424,14 @@ A @scheme[_struct-option] always starts with a keyword:
#:guard (lambda (name type-name)
(cond
[(string? name) name]
[(number? name)
(number->string name)]
[else (error "bad name" name)])))
[(symbol? name) (symbol->string name)]
[else (error type-name
"bad name: ~e"
name)])))
(make-thing "apple")
(make-thing 'apple)
(make-thing 1/2)
(make-thing #f)]
]
The guard is called even when subtype instances are created. In that
case, only the fields accepted by the constructor are provided to
@ -439,11 +444,11 @@ A @scheme[_struct-option] always starts with a keyword:
#:transparent
#:guard (lambda (name age type-name)
(if (negative? age)
(error "bad age" age)
(error type-name "bad age: ~e" age)
(values name age))))
(make-person "John" 10)
(make-person "Mary" -1)
(make-person #f 10)]}
(make-person 10 10)]}
@specspecsubform[(code:line #:property prop-expr val-expr)]{
Associates a @deftech{property} and value with the structure type.

4
collects/scribblings/reference/struct.scrbl
View File

@ -105,7 +105,7 @@ structures depends on the current inspector.)
Creates a new structure type, unless @scheme[inspector] is
@scheme['prefab], in which case @scheme[make-struct-type] accesses a
@techlink{prefab} structre type. The @scheme[name] argument is used
@techlink{prefab} structure type. The @scheme[name] argument is used
as the type name. If @scheme[super-type] is not @scheme[#f], the
resulting type is a subtype of the corresponding structure type.
@ -147,7 +147,7 @@ positions. Each element in the list must be unique, otherwise
@scheme[0] (inclusive) to @scheme[init-field-cnt] (exclusive), otherwise
@exnraise[exn:fail:contract].
The @scheme[guard] argument is either a procedure of @math{n}
The @scheme[guard] argument is either a procedure of @math{n+1}
arguments or @scheme[#f], where @math{n} is the number of arguments
for the new structure type's constructor (i.e.,
@scheme[init-field-cnt] plus constructor arguments implied by