Gerbil Scheme

Type Descriptor Utilities.

To use the bindings from this module:

(import :std/misc/rtd)

object-type

(object-type obj) -> type | error

  obj := object instance

Safe variant of runtime#object-type. Returns the class of an object; obj must be an object instance or an error is signaled.

Examples:

> (defstruct point (x y))
> (object-type (make-point 640 480))
#<type #4 point>
> (eq? point::t #4)
#t
> (object-type 12)
error    ; not segfaulting like runtime#object-type

type?

(type? typ) -> boolean

  typ := type object to check

Returns #t if obj is a type object, #f otherwise.

Examples:

> (defstruct point (x y))
> (type? point::t)
#t
> (type? (object-type (make-point -100 100)))
#t
> (type? (make-point 0 0))
#f

type-id

(type-id typ) -> type id | error

  typ := type object to inspect

Returns the id of the type object typ. Will signal an error if typ isn't a type object.

Examples:

> (defstruct a ())
> (defclass  b ())
> (type-id a::t)
#:a::t45
> (type-id b::t)
#:b::t49
> (type-id (object-type (make-b)))
#:b::t49

type=?

(type=? typ1 type2) -> bool

  typ1 := type object
  typ2 := other type object

Returns true if the two type objects have the same type-id. This is the preferred equality predicate for types. eq? and eqv? should also work, but at present equal? seems to be broken.

Examples:

> (defstruct a ())
> (defclass  b ())
> (type-id a::t)
#:a::t45
> (type-id b::t)
#:b::t49
> (type=? a::t a::t)
#t
> (type=? a::t b::t)
#f

type-name

(type-name typ) -> type name | error

  typ := type object to inspect

Returns the name of the type object typ. Will signal an error if typ isn't a type object.

Examples:

> (defstruct vec3i (x y z))
> (type-name (object-type (make-vec3i 30 0 15)))
vec3i

type-super

(type-super typ) -> super class | error

  typ := type object to inspect

Returns the super class of the type object typ. Will signal an error if typ isn't a type object.

Examples:

> (defstruct A (x y))
> (defstruct (B A) (z))
> (struct-subtype? A::t B::t)
#t
> (type-super B::t)
#<type #5 A>
> (type-super A::t)
#f

type-descriptor-mixin

(type-descriptor-mixin typ) -> list | error

  typ := type descriptor to inspect

Safe variant of runtime#type-descriptor-mixin. Returns the mixins of the type as a list. typ must be a type descriptor or an error is signaled.

Examples:

> (defclass A (x))
> (defclass (B A) (y))
> (defclass (C A) (z))
> (defclass (D B C) ())
> (type-descriptor-mixin D::t)
(#<type #8 B> #<type #9 C> #<type #10 A>)
> (type-descriptor-mixin B::t)
(#<type #10 A>)
> (type-descriptor-mixin A::t)
()

type-descriptor-fields

(type-descriptor-fields typ) -> fixnum | error

  typ := type descriptor to inspect

Safe variant of runtime#type-descriptor-fields. Returns the number of fields of the type as a fixnum. typ must be a type descriptor or an error is signaled.

Examples:

> (defstruct color (r g b a))
> (type-descriptor-fields color::t)
4

type-descriptor-plist

(type-descriptor-plist typ) -> alist | error

  typ := type descriptor to inspect

Safe variant of runtime#type-descriptor-plist. Returns the type properties of the type as an alist. typ must be a type descriptor or an error is signaled.

Examples:

> (defstruct vec4d (x y z w) final: #t)
> (type-descriptor-plist vec4d::t)
((fields: x y z w) (final: . #t))

type-descriptor-ctor

(type-descriptor-ctor typ) -> symbol | error

  typ := type descriptor to inspect

Safe variant of runtime#type-descriptor-ctor. Returns the constructor ID of the type as a symbol. typ must be a type descriptor or an error is signaled.

Examples:

> (defclass A (x) constructor: :init!)
> (defmethod {:init! A}
    (lambda (self x)
      (set! (A-x self) (* x 2))))
> (type-descriptor-ctor A::t)
:init!

type-descriptor-slots

(type-descriptor-slots typ) -> hash-table | error

  typ := type descriptor to inspect

Safe variant of runtime#type-descriptor-slots. Returns the slots of the type as a hash-table. typ must be a type descriptor or an error is signaled.

Examples:

> (defclass color (r g b a))
> (type-descriptor-slots color::t)
#<table #6>
> (hash->list #6)
((r . 0) (g . 1) (b . 2) (a: . 3) (g: . 1) (b: . 2) (r: . 0) (a . 3))

type-descriptor-methods

(type-descriptor-methods typ) -> hash-table | error

  typ := type descriptor to inspect

Safe variant of runtime#type-descriptor-methods. Returns the methods associated with the type as a hash-table. typ must be a type descriptor or an error is signaled.

Examples:

> (defclass A (x) constructor: :init!)
> (defmethod {:init! A}
    (lambda (self x)
      (set! (A-x self) (* x 2))))
> (type-descriptor-methods A::t)
#<table #11>
> (hash->list #11)
((:init! . #<procedure #12 A:::init!>))

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