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From: Noam Postavsky <npostavs@users.sourceforge.net>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: Emacs developers <emacs-devel@gnu.org>
Subject: Re: Obsolete string-to-multibyte hard to replace
Date: Mon, 29 May 2017 20:21:01 -0400	[thread overview]
Message-ID: <CAM-tV--CskdGmy8Or=50HZ_LyV0D9S73gVNHbi-=b8oognx3Zw@mail.gmail.com> (raw)
In-Reply-To: <jwvk24zj09b.fsf-monnier+emacs@gnu.org>

On Mon, May 29, 2017 at 9:01 AM, Stefan Monnier
<monnier@iro.umontreal.ca> wrote:
> I was looking at ruler-mode.el's bytecomp warning about string-to-multibyte
> and it seems like there is no good way to write cleaner code here:
>
>    (let (...
>          (ruler
>           (propertize
>            (string-to-multibyte
>             (make-string w ruler-mode-basic-graduation-char))
>             ...))
>          ...)
>     [...]
>           (aset ruler k (aref c (setq m (1- m))))
>
> Here, the problem is as follows: make-string returns a unibyte string if
> the initial char is ASCII and a multibyte string otherwise.
> Seems innucuous, but it means that if the initial char
> (ruler-mode-basic-graduation-char above) is ASCII, you can't later
> insert a multibyte char into that string with `aset`.

We could the collect the characters in a vector and then only convert
to string at the end. Haven't you said that strings should ideally be
treated as immutable?



  parent reply	other threads:[~2017-05-30  0:21 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-05-29 13:01 Obsolete string-to-multibyte hard to replace Stefan Monnier
2017-05-29 17:45 ` Eli Zaretskii
2017-05-30  4:03   ` Stefan Monnier
2017-05-30  0:21 ` Noam Postavsky [this message]
2017-05-30  3:28   ` Stefan Monnier

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