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Re: Why does using aset sometimes output raw bytes?
From: |
Eli Zaretskii |
Subject: |
Re: Why does using aset sometimes output raw bytes? |
Date: |
Mon, 10 Dec 2018 07:59:52 +0200 |
> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Date: Sun, 09 Dec 2018 16:20:59 -0500
>
> >> It's not the implementation, but the semantics of unibyte/multibyte
> >> strings presumes that the difference doesn't matter much for ASCII-only
> >> strings, which is mostly true but isn't true in the case of `aset`.
> > The same is true about concat, btw.
>
> I think it's less severe (`aset` can end up changing (by side-effect)
> a unibyte string to multibyte, i.e. changing the nature of the object,
> which I believe is the only time we do something like that), but yes
> similar problems appear elsewhere (hence the "mostly" above).
I'm not sure the "by side effect" part is an important distinction for
users, they might be surprised anyway. For example:
(let ((s1 "abcd")
(s2 "абвг"))
(message "s1: %s concat: %s"
(multibyte-string-p s1)
(multibyte-string-p (concat s1 s2))))
=> s1: nil concat: t
Some will say that this "converts" a unibyte string s1 to a multibyte
one just because it was concatenated.
People should always keep these gotchas in mind when working with
strings.
- Re: Why does using aset sometimes output raw bytes?, (continued)
- Re: Why does using aset sometimes output raw bytes?, Eli Zaretskii, 2018/12/09
- Re: Why does using aset sometimes output raw bytes?, Stephen Berman, 2018/12/09
- Re: Why does using aset sometimes output raw bytes?, Eli Zaretskii, 2018/12/09
- Re: Why does using aset sometimes output raw bytes?, Stephen Berman, 2018/12/09
- Re: Why does using aset sometimes output raw bytes?, Eli Zaretskii, 2018/12/09
Re: Why does using aset sometimes output raw bytes?, Stefan Monnier, 2018/12/09
Re: Why does using aset sometimes output raw bytes?, Stephen Berman, 2018/12/09