[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt
From: |
Lars Ingebrigtsen |
Subject: |
bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt |
Date: |
Tue, 21 Mar 2017 21:41:01 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/26.0.50 (gnu/linux) |
Michael Heerdegen <michael_heerdegen@web.de> writes:
> Stefan Monnier <monnier@iro.umontreal.ca> writes:
>
>> > (macroexp-let2 nil key
>> > `(progn
>> > (map--dispatch ,map
>> > :list (setf (alist-get ,key ,map nil t) nil)
>> > :hash-table (remhash ,key ,map)
>> > :array (and (>= ,key 0)
>> > (<= ,key (seq-length ,map))
>> > (aset ,map ,key nil)))
>> > ,map)))
>>
>> Note that this will make it pretty much impossible to use
>> cl-generic dispatch.
>
> It will also break cases where MAP is an expression that is not a
> symbol:
>
> #+begin_src emacs-lisp
> (let ((thing (cons 'tag (list (cons 0 1) (cons 2 3)))))
> (map-delete (cdr thing) 0))
> ==> nil
>
> (map-delete (list (cons 0 1) (cons 2 3)) 0)
> ==> if: Symbol's function definition is void: \(setf\ list\)
> #+end_src
If MAP isn't a symbol, then map-delete could avoid doing the setf,
couldn't it?
I think that should make for a pretty useful form. You can both say
...
(map-delete foo 'bar)
...
and
(setq foo (cons (map-delete (get-a-list) 'bar) 'zot))
and not be surprised at the results. It's certainly more fun than the
current (setq foo (delete 'bar foo)) we have all over the place, even if
it's something of a departure from how functions like this has
traditionally worked in various Lisps.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, (continued)
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Nicolas Petton, 2017/03/02
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Tino Calancha, 2017/03/02
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, npostavs, 2017/03/02
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Nicolas Petton, 2017/03/02
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Tino Calancha, 2017/03/02
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Stefan Monnier, 2017/03/02
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Michael Heerdegen, 2017/03/03
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Michael Heerdegen, 2017/03/03
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt,
Lars Ingebrigtsen <=
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Michael Heerdegen, 2017/03/22
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Lars Ingebrigtsen, 2017/03/22
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Noam Postavsky, 2017/03/22
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Lars Ingebrigtsen, 2017/03/22
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Michael Heerdegen, 2017/03/22
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Stefan Monnier, 2017/03/22
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Lars Ingebrigtsen, 2017/03/22
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Stefan Monnier, 2017/03/22
- bug#25929: 25.2; map-delete doesn't delete permanently 1st alist elt, Stefan Monnier, 2017/03/22
- bug#25929: 25.2; plists and map-*, Lars Ingebrigtsen, 2017/03/29