From: Stefan Monnier <monnier@iro.umontreal.ca>
To: akater <nuclearspace@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: [PATCH] Some improvements for cl-flet
Date: Sat, 02 Oct 2021 23:51:09 -0400 [thread overview]
Message-ID: <jwvy27aiy29.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <87k0j6gbjg.fsf@gmail.com> (akater's message of "Thu, 23 Sep 2021 22:41:23 +0000")
Hi,
Sorry for taking so long to review this.
This looks very complex for a macro that's used rather rarely.
Maybe it might be worthwhile splitting it into 2 or 3 patches so as to
better see how we got to the level of complexity.
See more comments below.
> --- a/lisp/emacs-lisp/cl-generic.el
I skipped this since `with-memoization` is now in `subr-x`.
> diff --git a/lisp/emacs-lisp/cl-macs.el b/lisp/emacs-lisp/cl-macs.el
> index 6d6482c349..ecbe8e86fc 100644
> --- a/lisp/emacs-lisp/cl-macs.el
> +++ b/lisp/emacs-lisp/cl-macs.el
> @@ -2004,6 +2004,282 @@ defun cl--labels-convert (f)
> (setq cl--labels-convert-cache (cons f res))
> res))))))
>
> +(defvar cl--flet-convert-with-setf-cache nil
> + "Like `cl--labels-convert-cache' but for local setf functions.")
> +
> +(defun cl--flet-convert-with-setf (f)
> + "Special macro-expander to rename (function F) references in `cl-flet', including (function (setf F)).
> +
> +See also `cl--labels-convert'."
> + ;; Note: If this function, or `cl--labels-convert', for that matter,
> + ;; is redefined at runtime,
> + ;; the whole replacement mechanism breaks!
> + (if (and (consp f) (eq 'setf (car f)))
> + (cond
> + ;; We repeat lots of code from `cl--labels-convert'
> + ((eq (cadr f) (car cl--flet-convert-with-setf-cache))
> + (cdr cl--flet-convert-with-setf-cache))
> + (t
> + (let* ((found (assoc f macroexpand-all-environment #'equal))
> + (replacement (and found
> + (ignore-errors
> + (funcall (cdr found) cl--labels-magic)))))
> + (if (and replacement (eq cl--labels-magic (car replacement)))
> + (nth 1 replacement)
> + (let ((res `(function ,f)))
> + (setq cl--flet-convert-with-setf-cache (cons (cadr f) res))
> + res)))))
> + (cl--labels-convert f)))
I didn't get to the point of trying to understand this.
> +(defmacro with--cl-flet-macroexp ( arglist var
> + function-name expander memoized-alist
> + &rest body)
All the defs should start with "cl-" so it should be `cl--with...`.
> +(defun cl--expand-local-setf (&rest places-and-values)
> + "Expand `(setf . ,PLACES-AND-VALUES)
> +according to `cl--local-setf-expanders'.
> +
> +Presumes the caller has `macroexpand-all-environment' bound."
Why do we have/need this? Does it work with other things that use
gv-places, like `push`, `pop`, `cl-callf`, ...? If so, how?
If not, then we need another approach which does.
I thought handling `cl-flet` of (setf foo) would amount to calling
`gv-setter` to get the symbol corresponding to `(setf foo)` and then
c-flet-binding that symbol instead of `(setf foo).
> +(defun cl--expand-flet (env body &rest flet-expanders-plist)
> + "Return a form equivalent to `(cl-flet ,bindings BODY)
> +where bindings correspond to FLET-EXPANDERS-PLIST as described below.
> +
> +ENV should be macroexpansion environment
> +to be augmented with some definitions from FLET-EXPANDERS-PLIST
> +to then expand forms in BODY with.
> +
> +FLET-EXPANDERS-PLIST should be a plist
> +where keys are function names
> +and values are 0-argument lambdas
> +to be called if the corresponding function name is encountered
> +in BODY and then only (that is, at most once).
Why "at most once"?
> +The return value of said lambdas should be either
> +
> +- a valid let-binding (SYMBOL function) to be used in let*
> + bindings over BODY so that SYMBOL could be used in place of the
> + corresponding function name in BODY
> +
> +or
> +
> +- a list (NIL EXPR) for EXPR to be used in BODY in place of the
> + corresponding function name as is.
Can we simplify this so only one of the two is supported?
Stefan
next prev parent reply other threads:[~2021-10-03 3:51 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-11 12:51 Some improvements for cl-flet akater
2021-09-11 23:32 ` Michael Heerdegen
2021-09-12 3:35 ` akater
2021-09-12 15:38 ` Stefan Monnier
2021-09-13 0:14 ` Michael Heerdegen
2021-09-13 2:26 ` Stefan Monnier
2021-10-07 2:32 ` akater
2021-10-07 18:03 ` Stefan Monnier
2021-10-08 21:57 ` Richard Stallman
2021-10-09 5:23 ` akater
2021-10-09 6:01 ` Michael Heerdegen
2021-10-09 23:37 ` Richard Stallman
2021-10-10 10:41 ` Po Lu
2021-10-10 20:27 ` João Távora
2021-10-10 21:57 ` Stefan Monnier
2021-10-11 0:45 ` [External] : " Drew Adams
2021-10-11 21:16 ` Richard Stallman
2021-10-11 21:26 ` João Távora
2021-10-12 22:42 ` Richard Stallman
2021-10-12 0:05 ` Po Lu
2021-10-12 0:29 ` Robin Tarsiger
2021-10-12 22:43 ` Richard Stallman
2021-10-09 23:33 ` Richard Stallman
2021-10-09 23:33 ` Richard Stallman
2021-10-14 4:00 ` Michael Heerdegen
2021-09-23 22:37 ` [PATCH] " akater
2021-09-23 22:41 ` akater
2021-09-24 7:11 ` João Távora
2021-09-24 15:20 ` [PATCH] Some improvements for cl-flet, and some more akater
2021-09-24 16:22 ` João Távora
2021-09-25 1:28 ` Lars Ingebrigtsen
2021-09-25 8:37 ` João Távora
2021-09-24 20:30 ` [PATCH] Some improvements for cl-flet akater
2021-09-26 6:54 ` Lars Ingebrigtsen
2021-09-26 12:04 ` akater
2021-09-26 12:36 ` Lars Ingebrigtsen
2021-10-03 3:51 ` Stefan Monnier [this message]
2021-10-07 5:02 ` akater
2021-10-07 18:23 ` Stefan Monnier
2021-11-03 12:59 ` akater
2021-11-09 20:37 ` Stefan Monnier
2021-10-09 5:33 ` akater
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