From: "Eric M. Ludlam" <eric@siege-engine.com>
To: Chong Yidong <cyd@stupidchicken.com>
Cc: emacs-devel@gnu.org
Subject: Re: EIEIO and CL
Date: Fri, 09 Oct 2009 16:05:40 -0400 [thread overview]
Message-ID: <1255118740.6961.443.camel@projectile.siege-engine.com> (raw)
In-Reply-To: <87ocogtsr8.fsf@stupidchicken.com>
On Fri, 2009-10-09 at 12:51 -0400, Chong Yidong wrote:
> Currently, the EIEIO library requires CL at runtime. This is mainly due
> to needing `deftype' and `typep' (EIEIO implements a subset of the CLOS
> spec, which demand their existence). If possible, it would be nice to
> reduce this to a compile-time dependency, so that loading Semantic or
> EDE does not load the CL library.
>
> The `typep' requirement is solvable; the `deftype' requirement is the
> more interesting. Currently, eieio-defclass contains this code:
>
> ;; When using typep, (typep OBJ 'myclass) returns t for objects which
> ;; are subclasses of myclass. For our predicates, however, it is
> ;; important for EIEIO to be backwards compatible, where
> ;; myobject-p, and myobject-child-p are different.
> ;; "cl" uses this technique to specify symbols with specific typep
> ;; test, so we can let typep have the CLOS documented behavior
> ;; while keeping our above predicate clean.
> (eval `(deftype ,cname ()
> '(satisfies
> ,(intern (concat (symbol-name cname) "-child-p")))))
>
> The problem here is that the `cname' argument to the deftype CL macro
> is, in general, determined at run-time.
>
> Another possibility is to change eieio-defclass so that it defers this
> deftype form till CL is loaded, by putting it on cl-macs-load-hook.
> This assumes that the deftype is only useful if some later code calls
> typep or typecase; if this assumption is wrong, that could lead to
> subtle bugs.
>
> Or, there may be a way to change `deftype' (or to provide a different CL
> macro) that can do the right thing at compile-time.
>
> Any suggestions?
Hi,
The defclass operation in EIEIO is a macro that calls out to a helper
function. This is because I have found that I'm just not that good at
writing macros. I would guess that if the entirety of eieio-defclass
were turned into a macro, then the whole eval thing you quoted above
would become a compile time requirement only. Would it then be a
requirement during compilation of code that uses defclass, as opposed to
a compile time requirement of eieio.el?
Alternately, it would be cool if typep, or something similar was a part
of Emacs core. Wouldn't the widget/custom setup like that?
Eric
next prev parent reply other threads:[~2009-10-09 20:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-09 16:51 EIEIO and CL Chong Yidong
2009-10-09 20:05 ` Eric M. Ludlam [this message]
2009-10-09 20:36 ` Chong Yidong
-- strict thread matches above, loose matches on Subject: below --
2009-10-09 22:29 S+*n_Pe*rm*n
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1255118740.6961.443.camel@projectile.siege-engine.com \
--to=eric@siege-engine.com \
--cc=cyd@stupidchicken.com \
--cc=emacs-devel@gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.