From: Dmitry Gutov <dgutov@yandex.ru>
To: Michael Heerdegen <michael_heerdegen@web.de>
Cc: 23430@debbugs.gnu.org, Stefan Kangas <stefan@marxist.se>
Subject: bug#23430: 25.0.93; iter-defun does not support special form save-current-buffer
Date: Sat, 22 Aug 2020 03:18:08 +0300 [thread overview]
Message-ID: <87fd8e2a-6566-b451-48af-e1966ce1f8eb@yandex.ru> (raw)
In-Reply-To: <87tux2btql.fsf@web.de>
On 16.08.2020 16:33, Michael Heerdegen wrote:
> Dmitry Gutov <dgutov@yandex.ru> writes:
>
>> Before we close this, I'd like to hear from somebody who understands
>> what generator.el is actually for.
>
> I think it's just a straightforward implementation of generators as
> described here:
>
> https://en.wikipedia.org/wiki/Generator_%28computer_programming%29
>
> I learned about them in university, and have used them once in a while.
Right. I was really wondering, though, whether we can/should use them
more often.
> AFAIK handling asynchronous process output is not a good task for them.
Perhaps if we also used a separate thread for waiting for the output to
come...
> I think: The problem of the concept of generators in an editor is that
> generators are good for saving the state of a computation, but Emacs as
> an editor has a lot of "environment" state (current buffer, value of
> point, ...), and when the computation represented by the generator
> messes with this state (or has side effects), the concept doesn't fit
> that well.
>
> When working with streams, I make the handling of the according part of
> the environment explicit saving it in variables (iterators are closures)
> and "yield" outside of any xxx-recursion, in your introductory example,
> that would look like this:
>
> #+begin_src emacs-lisp
> (require 'generator)
>
> (iter-defun my-search (str buf)
> (with-current-buffer buf
> (goto-char (point-min)))
> (let ((pos (point))
> (yield nil)
> (done nil))
> (while (not done)
> (when yield
> (iter-yield yield)
> (setq yield nil))
> (with-current-buffer buf
> (goto-char pos)
> (if (search-forward str)
> (setq yield (match-beginning 0)
> pos (point))
> (setq done 0))))))
> #+end_src
Thanks. I think this is fairly close to the approach I showed in the
patch. Problem is, it's no shorter than an implementation one can write
using plain functions. Longer, usually.
> I guess it would be nice if that could work implicitly in some way, but
> that would probably require the introduction of new special forms
> adapted to the situation, like `iterator-save-buffer-and-point' or so.
Perhaps.
next prev parent reply other threads:[~2020-08-22 0:18 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-03 1:31 bug#23430: 25.0.93; iter-defun does not support special form save-current-buffer Dmitry Gutov
2016-05-05 22:46 ` Dmitry Gutov
2016-05-06 23:25 ` Michael Heerdegen
2016-05-06 23:30 ` Dmitry Gutov
2020-08-12 2:41 ` Stefan Kangas
2020-08-12 10:06 ` Dmitry Gutov
2020-08-16 13:33 ` Michael Heerdegen
2020-08-22 0:18 ` Dmitry Gutov [this message]
2020-08-18 12:08 ` Michael Heerdegen
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