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Rename final? record type flag; add support for opaque?

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* module/ice-9/boot-9.scm (record-type-extensible?): Rename from
  record-type-final?, with the opposite sense.
  (record-type-opaque?): New accessor.
  (make-record-type): Change #:final? to #:extensible?, with the
  opposite meaning.  Add #:opaque? arg.
* test-suite/tests/records.test ("records"): Add opaque tests; update
  extensible tests.
* doc/ref/api-data.texi (Records): Update.
* module/srfi/srfi-35.scm (&condition, make-condition-type): Update for
  make-record-type API change.
This commit is contained in:
Andy Wingo 2019-10-27 21:28:21 +01:00
commit f963bdf02d
4 changed files with 51 additions and 21 deletions
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19
doc/ref/api-data.texi
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@ -8631,7 +8631,8 @@ promise that records are disjoint with other Scheme types.
@end deffn
@deffn {Scheme Procedure} make-record-type type-name field-names [print] @
[#:final?=@code{#t}] [#:parent=@code{#f}] [#:uid=@code{#f}]
[#:parent=@code{#f}] [#:uid=@code{#f}] @
[#:extensible?=@code{#f}] [#:opaque?] @
Create and return a new @dfn{record-type descriptor}.
@var{type-name} is a string naming the type. Currently it's only used
@ -8654,11 +8655,11 @@ followed by fields declared in the @code{make-record-type} call. Record
predicates and field accessors for instance of a parent type will also
work on any instance of a subtype.
@cindex final record types
@cindex record types, final
@cindex extensible record types
@cindex record types, extensible
Allowing record subtyping has a small amount of overhead. To avoid this
overhead, declare the record type as @dfn{final} by passing
@code{#:final? #t}. Record types in Guile are final by default.
overhead, prevent extensibility by passing @code{#:extensible? #f}.
By default, record types in Guile are not extensible.
@cindex prefab record types
@cindex record types, prefab
@ -8671,6 +8672,14 @@ symbol as the @code{#:uid} keyword parameter. If a record with the
given @var{uid} was already defined, it will be returned instead. The
type name, fields, parent (if any), and so on for the previously-defined
type must be compatible.
@cindex record types, opaque
R6RS defines a notion of ``opaque'' record types. Given an instance of
an opaque record type, one cannot obtain a run-time representation of
the record type. @xref{rnrs records procedural}, for full details. The
@code{#:opaque?} flag is used by Guile's R6RS layer to record this
information. The default is determined by whether the parent type, if
any, was opaque.
@end deffn
@deffn {Scheme Procedure} record-constructor rtd