CFFI User Manual - Common Lisp.net

Chapter 6: Foreign Types 38
define-foreign-type
Syntax
define-foreign-type class-name supers slots &rest options ⇒ [Macro]
class-name
options ::= (:actual-type type) | (:simple-parser symbol) | regular defclass option
Arguments and Values
class-name
supers
slots
Description
A symbol naming the new foreign type class.
A list of symbols naming the super classes.
A list of slot definitions, passed to defclass.
The macro define-foreign-type defines a new class class-name. It is a thin wrapper
around defclass. Among other things, it ensures that class-name becomes a subclass of
foreign-type, what you need to know about that is that there’s an initarg :actual-type
which serves the same purpose as defctype’s base-type argument.
Examples
Taken from CFFI’s :boolean type definition:
(define-foreign-type :boolean (&optional (base-type :int))
"Boolean type. Maps to an :int by default. Only accepts integer types."
(ecase base-type
((:char
:unsigned-char
:int
:unsigned-int
:long
:unsigned-long) base-type)))
CFFI> (canonicalize-foreign-type :boolean)
⇒ :INT
CFFI> (canonicalize-foreign-type ’(:boolean :long))
⇒ :LONG
CFFI> (canonicalize-foreign-type ’(:boolean :float))
;; error signalled by ECASE.
See Also
[defctype], page 36
[define-parse-method], page 39