Hi Andy, Andy Wingo <wi...@pobox.com> writes:
> If you know GOOPS, then you know that we have classes, rooted at > <class>. And indeed <class> shows up a lot in documentation and in > code. But that's not how it is in CLOS: our <class> corresponds to > their `standard-class'. They have a superclass, called `class', which > is the real root, and from which e.g. structure classes are derived. > > We need to do this. Currently, class-of on a struct/record data type > gives a useless class that can't instantiate instances, doesn't know its > slots, and does not reflect the vtable hierarchy. Here’s an illustration: --8<---------------cut here---------------start------------->8--- scheme@(guile-user)> (use-modules (oop goops) (srfi srfi-9)) scheme@(guile-user)> (define-record-type <foo> (make-foo x) foo? (x foo-x)) scheme@(guile-user)> (make-foo 2) $3 = #<<foo> x: 2> scheme@(guile-user)> (class-of $3) $4 = #<<class> <> 148a4b0> scheme@(guile-user)> (class-slots $4) $5 = () scheme@(guile-user)> (class-of $4) $6 = #<<class> <class> 8e7a50> --8<---------------cut here---------------end--------------->8--- > So we need a <basic-class>, interposed between <class> and <object>, > which will be the real root of our class meta-object hierarchy. Why? Couldn’t ‘scm_i_define_class_for_vtable’ build a full-blown class, populating its CPL, its ‘slots’ slot, etc.? Thanks, Ludo’.
