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expose struct:struct-info

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svn: r8753
This commit is contained in:
Matthew Flatt 2008-02-21 13:30:25 +00:00
parent 3740b05660
commit b953b448ba
2 changed files with 22 additions and 14 deletions
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24
collects/scheme/private/struct-info.ss
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@ -7,9 +7,10 @@
(#%provide make-struct-info (#%provide make-struct-info
struct-info? struct-info?
extract-struct-info) extract-struct-info
struct:struct-info)
(define-values (struct:struct-info create-struct-info struct-info-rec? (define-values (struct:struct-info make-struct-info struct-info-rec?
struct-info-ref struct-info-set!) struct-info-ref struct-info-set!)
(make-struct-type 'struct-info #f (make-struct-type 'struct-info #f
1 0 #f 1 0 #f
@ -18,16 +19,15 @@
(raise-syntax-error (raise-syntax-error
#f #f
"identifier for static struct-type information cannot be used as an expression" "identifier for static struct-type information cannot be used as an expression"
stx)))) stx))
null
(define-values (make-struct-info) (lambda (proc info)
(lambda (proc) (if (and (procedure? proc)
(if (and (procedure? proc) (procedure-arity-includes? proc 0))
(procedure-arity-includes? proc 0)) proc
(create-struct-info proc) (raise-type-error 'make-struct-info
(raise-type-error 'make-struct-info "procedure (arity 0)"
"procedure (arity 0)" proc)))))
proc))))
(define-values (extract-struct-info) (define-values (extract-struct-info)
(lambda (si) (lambda (si)

12
collects/scribblings/reference/struct.scrbl
View File

@ -361,8 +361,8 @@ information can be used during the expansion of other expressions via
@scheme[syntax-local-value]. @scheme[syntax-local-value].
For example, the @scheme[define-struct] variant for subtypes uses the For example, the @scheme[define-struct] variant for subtypes uses the
base type name @scheme[t] to find the variable base type name @scheme[_t] to find the variable
@scheme[struct@scheme[:t]] containing the base type's descriptor; it @schemeidfont{struct:}@scheme[_t] containing the base type's descriptor; it
also folds the field accessor and mutator information for the base also folds the field accessor and mutator information for the base
type into the information for the subtype. As another example, the type into the information for the subtype. As another example, the
@scheme[match] form uses a type name to find the predicates and field @scheme[match] form uses a type name to find the predicates and field
@ -449,3 +449,11 @@ form.}
Extracts the list form of the structure type information represented Extracts the list form of the structure type information represented
by @scheme[v].} by @scheme[v].}
@defthing[struct:struct-info struct-type?]{
The @tech{structure type descriptor} for the structure type returned
by @scheme[make-struct-info]. This @tech{structure type descriptor} is
mostly useful for creating structure subtypes. The structure type
includes a guard that checks an instance's first field in the same way
as @scheme[make-struct-info].}