From: Kevin Rodgers <kevin.d.rodgers@gmail.com>
To: bug-gnu-emacs@gnu.org
Subject: bug#7086: `booleanp' return value is multi-valued list
Date: Wed, 22 Sep 2010 20:06:02 -0600 [thread overview]
Message-ID: <i7ecm9$uth$1@dough.gmane.org> (raw)
In-Reply-To: <AANLkTim5_1H+hiUHP9vi4gszpvm-vydugvjA9k7HR6fH@mail.gmail.com>
On 9/22/10 4:35 PM, Juanma Barranquero wrote:
> On Wed, Sep 22, 2010 at 23:58, MON KEY<monkey@sandpframing.com> wrote:
>
>> "Return non-`nil' if OBJECT is one of the two canonical boolean
>> values: `t' or `nil'."
>>
>> It should be documented both in the manual and the docstring of `booleanp' that
>> its return value is a list.
>
> Why? It is a type predicate. If anything, it should be changed to
> return t or nil, as "(elisp)2.6 Type Predicates" says:
>
> A type predicate function takes one argument; it returns `t' if the
> argument belongs to the appropriate type, and `nil' otherwise.
>
> The fact that it returns nil or a list is an implementation detail.
>
>> Indeed, while I can appreciate why (booleanp nil) returns a two element list
>> I'm unable to reason a rationale for why (booleanp t) doesn't?
>
> Why do you expect any kind of rationale, other than the simple fact
> that it is implemented as
>
> (memq object '(nil t)))
(and (memq object '(nil t))
t)
would be better.
--
Kevin Rodgers
Denver, Colorado, USA
next prev parent reply other threads:[~2010-09-23 2:06 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-22 21:58 bug#7086: `booleanp' return value is multi-valued list MON KEY
2010-09-22 22:35 ` Juanma Barranquero
2010-09-23 2:06 ` Kevin Rodgers [this message]
2010-09-23 10:29 ` Juanma Barranquero
2010-10-03 1:11 ` Chong Yidong
2010-09-23 4:22 ` MON KEY
2010-09-23 10:31 ` Juanma Barranquero
2010-09-23 8:12 ` Eli Zaretskii
2010-09-24 6:41 ` MON KEY
2010-09-24 8:48 ` Juanma Barranquero
2010-09-24 9:28 ` Lawrence Mitchell
2010-09-24 22:00 ` MON KEY
2010-09-25 9:18 ` Juanma Barranquero
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