From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Drew Adams <drew.adams@oracle.com>
Cc: emacs-devel@gnu.org
Subject: Re: 1) (elisp) `Advising Named Functions', 2) search filtering example
Date: Mon, 17 Oct 2016 13:47:29 -0400 [thread overview]
Message-ID: <jwv4m4ac1zm.fsf-monnier+Inbox@gnu.org> (raw)
In-Reply-To: <14560de9-7ab9-4d97-80dd-d4b84274affb@default> (Drew Adams's message of "Mon, 17 Oct 2016 10:05:51 -0700 (PDT)")
> #[128 <some-byte-code> [apply (lambda (b e) (save-excursion
> (goto-char e) (eolp))) isearch-filter-visible ((name . "eol")
> (isearch-message-prefix . "eol, "))] 4 nil]
> Dunno what you want to call such a thing.
A function object (a closure). More specifically a function which is
the composition of two or more functions. You could get a similar
function without using add-function, but using instead something like
(setq isearch-filter-predicate
(let ((old isearch-filter-predicate))
(lambda (&rest args)
(and (apply <f> args)
(apply old args)))))
> To me, the new advice doc is not as helpful as it should be,
> and the thingies dealt with are not clear or clearly presented.
To me, they're not as obscure as they should be: in my world, functions
are black boxes (you only get to know their type).
If you do
(setq isearch-filter-predicate (symbol-function isearch-filter-predicate))
you end up with a variable that behaves pretty much exactly as before,
but if you look at the value of `isearch-filter-predicate` it will
suddenly look like some gobbledygook as well. The fact that sometimes
you get a symbol is just an accident.
> If you cannot or will not, I'm still hoping that someone else will
> improve the doc and make things clearer, for all.
I have no idea how to improve the doc, so feel free to try and do it.
In the past I've had some luck with a "generate&test" approach, where
someone writes a tentative doc, and I point out the factual errors in it,
repeating the process until the doc is both understandable and correct.
Stefan
next prev parent reply other threads:[~2016-10-17 17:47 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-17 5:25 1) (elisp) `Advising Named Functions', 2) search filtering example Drew Adams
2016-10-17 12:20 ` Noam Postavsky
2016-10-17 14:02 ` Drew Adams
2016-10-17 14:37 ` Noam Postavsky
2016-10-17 14:52 ` Stefan Monnier
2016-10-17 15:40 ` Drew Adams
2016-10-17 15:51 ` Stefan Monnier
2016-10-17 17:05 ` Drew Adams
2016-10-17 17:47 ` Stefan Monnier [this message]
2016-10-17 15:40 ` Drew Adams
2016-10-17 16:16 ` Noam Postavsky
2016-10-17 17:05 ` Drew Adams
2016-10-17 17:53 ` Stefan Monnier
2016-10-17 18:41 ` Drew Adams
2016-10-17 19:25 ` Stefan Monnier
2016-10-18 19:47 ` Richard Stallman
2016-10-19 6:15 ` Eli Zaretskii
2016-10-19 20:00 ` Richard Stallman
2016-10-19 20:18 ` Stefan Monnier
2016-10-20 7:17 ` Eli Zaretskii
2016-10-20 7:06 ` Eli Zaretskii
2016-10-20 18:06 ` Richard Stallman
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