From: MON KEY <monkey@sandpframing.com>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: emacs-devel@gnu.org
Subject: Re: `setplist' on local var escaping let binding
Date: Wed, 20 Oct 2010 23:02:07 -0400 [thread overview]
Message-ID: <AANLkTinkfo5ZUWZkhh3KT7ibTDA-TeWUAxWmxOSz34dP@mail.gmail.com> (raw)
In-Reply-To: <jwvhbggcpwa.fsf-monnier+emacs@gnu.org>
On Wed, Oct 20, 2010 at 9:10 PM, Stefan Monnier
<monnier@iro.umontreal.ca> wrote:
>> I noticed today that if I `setplist' on a null let bound local var
>
> The above shows a misunderstanding: setplist does not operate on
> variables but on symbols.
What is this then: 'a-quoted-variable-but-not-a-symbol ?
Are you saying that `setplist' is only for top-level symbols?
Doesn't quoting the variable intern?
(let (ms)
(setplist 'ms '(can-has a-plist))
`(,(get 'ms 'can-has)
,(intern-soft "ms" obarray)))
;=> (a-plist ms)
(get 'ms 'can-has)
;=> a-plist
Appears to.
Whichever. I still don't understand how/why following happens
(nor how your answer addresses it):
(progn
(unintern "ms" obarray)
(let (ms)
(setplist 'ms '(can-has a-plist))
`(,(get 'ms 'can-has)
,(intern-soft "ms" obarray))))
(a-plist nil)
;=> (a-plist nil)
(get 'ms 'can-has)
;=> nil
So what am i missing?
In following `ms' is a "thing-like" bound to an uninterned "non-thing"
`bubba'. `ms' is on obarray `bubba' isn't and his symbol-value void.
(let ((ms (make-symbol "bubba")))
(list :thing-like (intern-soft "ms" obarray)
:non-thing (intern-soft "bubba" obarray)))
;=> (:thing-like ms :non-thing nil)
make sure its all clear:
(progn
(intern-soft "bubba" obarray)
(unintern "bubba" obarray)
(intern-soft "ms" obarray)
(unintern "ms" obarray))
In following the "non-thing" `bubba' has a plist and the thing-like is interned:
(let ((ms (make-symbol "bubba")))
(apply #'setplist
(list (eval (list 'quote (identity ms)))
'(not a symbol really?)))
`(:non-thing-bubba ,(not (intern-soft "bubba" obarray))
:but-with-a-plist ,(apply #'get
(list (eval (list 'quote (identity ms)))
'symbol))
:is-thing-like-ms ,(eq (intern-soft "ms" obarray)
(intern-soft "ms" obarray))))
;=> (:non-thing-bubba t
; :but-with-a-plist really\?
; :is-thing-like-ms t)
> Stefan
--
/s_P\
next prev parent reply other threads:[~2010-10-21 3:02 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-20 23:28 `setplist' on local var escaping let binding MON KEY
2010-10-21 1:10 ` Stefan Monnier
2010-10-21 3:02 ` MON KEY [this message]
2010-10-21 4:26 ` Stephen J. Turnbull
2010-10-21 9:06 ` Andreas Schwab
2010-10-21 12:46 ` Davis Herring
2010-10-21 13:35 ` Thien-Thi Nguyen
2010-10-21 18:38 ` Stefan Monnier
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