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Re: GOOPS todo
From: |
Ludovic Courtès |
Subject: |
Re: GOOPS todo |
Date: |
Thu, 24 Apr 2008 00:03:26 +0200 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.1 (gnu/linux) |
Hi Andy!
Andy Wingo <address@hidden> writes:
> * Generic application only works for instances of <generic>, or for
> instances of a couple of other specially blessed classes. This is
> because for these classes, the C code knows how the objects will be
> laid out in memory, and can access memory directly instead of using
> slot-ref. In general in GOOPS (and in MOPs in general) there is a
> tension between extensibility and efficiency; the former is expressed
> in protocols of generic functions, and the latter in invariants and
> possibilities for direct memory access.
>
> The evaluator really needs to be able to do direct memory access, if
> possible. So for that reason the existing bits of generic function
> dispatch that are wired into eval.c check instances of those blessed
> clases, via checks like (SCM_OBJ_CLASS_FLAGS (proc) &
> SCM_CLASSF_PURE_GENERIC).
>
> This "direct memory access" also has repercussions in tail recursion;
> that if the code to dispatch a method can't bottom out in eval.c, we
> lose tail recursion.
>
> So, we need to add support for instances of subclasses of <generic>,
> without losing efficiency. Apparently there is some code for this, see
> goops.scm:apply-generic.
(I realize this answers my previous message on `guile-user'...)
Good to see you have idea on this! :-)
> * We have no :before or :after methods. I don't know if STKlos had these
> either.
Not sure, but a nice thing to have.
> * GOOPS should define a with-accessors macro.
Actually, I don't like it a lot (probably because I wouldn't mind adding
accessors to the global namespace). Do other CLOS-like systems have
something similar?
> * GOOPS reference should be folded into Guile's reference, as it is now
> part of Guile.
Not sure about it since it's quite a large document and it's easier to
search it when it's separate.
> * Possibly the worst section of Guile's manual:
I like this one. :-)
> * method cache code could be rewritten in C (dispatch.scm), although I
> have never had a problem with it -- it doesn't show up on my profiles.
I'd be reluctant to this, as it's already complex enough.
Thanks for this instructing (and entertaining) review!
Ludo'.
- GOOPS todo, Andy Wingo, 2008/04/19
- Re: GOOPS todo,
Ludovic Courtès <=