From: Lars Ingebrigtsen <larsi@gnus.org>
To: Eli Barzilay <eli@barzilay.org>
Cc: 17507@debbugs.gnu.org
Subject: bug#17507: Documentation for `add-text-property' and relatives
Date: Wed, 14 Aug 2019 16:57:44 -0700 [thread overview]
Message-ID: <87a7cbti4n.fsf@mouse.gnus.org> (raw)
In-Reply-To: <21365.44878.936634.958813@home.barzilay.org> (Eli Barzilay's message of "Fri, 16 May 2014 02:25:18 -0400")
Eli Barzilay <eli@barzilay.org> writes:
> What I was surprised to find out is that
>
> (let ((s "foo")) (put-text-property 0 3 'foo 'bar s) s)
>
> works. It's probably obvious for elisp hackers, but coming from
> most other lisps/schemes, I kind of assumed that the #("foo" ...)
> thing is made of the "foo" string in some vector-like container that
> holds the properties. Given that unconscious assumption, I assumed
> that it wouldn't work, and that I'll need some uglier hack like
>
> (let ((s (propertize "foo" 'foo nil)))
> (put-text-property 0 3 'foo 'bar s) s)
>
> so that `s' points to an object that can be mutated inside.
>
> So I think that it would be a good idea to add a comment in the docs
> (of all of these functions) that notes that when given a string, they
> mutate it, and it works even if the input is property-less. Or just
> make it easier with showing a example as the above.
>
> (Hopefully the above makes sense -- I wonder how many lispers who are
> not native e-lispers have that assumption...)
(I'm going through old bug reports that have unfortunately gotten no
responses yet.)
Hm... I think the doc string is pretty clear here:
---
If the optional fifth argument OBJECT is a buffer (or nil, which means
the current buffer), START and END are buffer positions (integers or
markers). If OBJECT is a string, START and END are 0-based indices into it.
---
I understand that if you come from a C background (or something like
that) your assumption may be that a string is just a bunch of bytes with
a null at the end, so you can't add any properties to it -- but that's
not the case in most languages, where a string is an object with lots of
different qualities in addition to the text itself.
So I don't think this is something that's desirable to explain in this
specific context, and I'm closing this bug report.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
next prev parent reply other threads:[~2019-08-14 23:57 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-16 6:25 bug#17507: Documentation for `add-text-property' and relatives Eli Barzilay
2019-08-14 23:57 ` Lars Ingebrigtsen [this message]
2019-08-15 3:41 ` Eli Barzilay
2019-08-15 14:30 ` Eli Zaretskii
2019-08-16 1:35 ` Eli Barzilay
2019-08-16 8:46 ` Eli Zaretskii
2019-08-16 20:04 ` Lars Ingebrigtsen
2019-08-17 6:47 ` Eli Zaretskii
2019-08-17 22:22 ` Richard Stallman
2019-08-16 23:49 ` Eli Barzilay
2019-08-17 6:41 ` Eli Zaretskii
2019-08-17 12:40 ` Eli Barzilay
2019-08-17 12:46 ` Eli Zaretskii
2019-08-16 1:20 ` Lars Ingebrigtsen
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