GNU bug report logs - #76611
30.1; Elisp manual: Say what it means for a char to be printable

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Message #8 received at 76611 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Drew Adams <drew.adams <at> oracle.com>
Cc: 76611 <at> debbugs.gnu.org
Subject: Re: bug#76611: 30.1;
 Elisp manual: Say what it means for a char to be printable
Date: Fri, 28 Feb 2025 16:32:55 +0200

> Date: Thu, 27 Feb 2025 17:48:40 +0000
> From:  Drew Adams via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs <at> gnu.org>
> 
> (elisp)`Character Properties' describes variable `printable-chars', but
> it doesn't say what "printable" means in this context.  Please add
> something about that.
> 
> Searching the manual elsewhere, we find only a mention in node `Usual
> Display' of "printable ASCII characters" and non-printable ASCII control
> characters".
> 
> But the printable chars, in general, are not limited to printable ASCII
> control chars, so this mention doesn't help with understanding
> `printable-chars'.

If you don't know what are printable characters, how did you deduce
that they are not limited to ASCII?  (No, don't answer that.)

> Please say what's meant by "printable" for `printable-chars'.

I added on the master branch a cross-reference to where the [:print:]
regexp character class is described, because that's what "printable
character" means in Emacs.

But the more serious problem with the printable-chars table was that
its value was incorrect for many Unicode codepoints; I fixed that as
well.

> [ And I wonder if something shouldn't perhaps be added about (Lisp)
> readability in this context.  Some things in Lisp have a print
> representation but that can't be read by the Lisp reader.  I believe all
> printable chars can be read by the reader.  It wouldn't hurt to mention
> this. ]

I don't understand what you are trying to say here.  Is something
missing from the "Character Type" node of the ELisp manual and its
sub-nodes, wrt the read syntax of characters?

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