GNU bug report logs - #10460
24.0.92; css-mode sexp movement

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Message #20 received at 10460 <at> debbugs.gnu.org (full text, mbox):

From: Tom Tromey <tom <at> tromey.com>
To: Stefan Monnier <monnier <at> iro.umontreal.ca>
Cc: Tom Tromey <tom <at> tromey.com>, 10460 <at> debbugs.gnu.org, Leo <sdl.web <at> gmail.com>
Subject: Re: bug#10460: 24.0.92; css-mode sexp movement
Date: Mon, 29 Dec 2014 09:35:50 -0700

>> When I do this, point moves to the "a".
Stefan> It skipped a "statement".

>> This seems clearly wrong to me
>> -- I think point should be left at the "{".
Stefan> Why?

I was going just by how I "know" emacs works, based on using various
other modes for years and years.  That is, consistency with C mode, js
mode, tcl mode, etc.

The docs also indicate that this is how Emacs works.
From "(emacs) Expressions":

    Each programming language mode has its own definition of a "balanced
    expression".  Balanced expressions typically include individual symbols,
    numbers, and string constants, as well as pieces of code enclosed in a
    matching pair of delimiters.
[...]
       To move forward over a balanced expression, use ‘C-M-f’
    (‘forward-sexp’).  If the first significant character after point is an
    opening delimiter (e.g., ‘(’, ‘[’ or ‘{’ in C), this command moves past
    the matching closing delimiter.  If the character begins a symbol,
    string, or number, the command moves over that.
[...]
       The command ‘C-M-b’ (‘backward-sexp’) moves backward over a balanced
    expression—like ‘C-M-f’, but in the reverse direction.  If the
    expression is preceded by any prefix characters (single-quote, backquote
    and comma, in Lisp), the command moves back over them as well.


I suppose this supplies a bit of wiggle room, if you leniently interpret
"prefix characters".

That said it just seems weird to me that, when point is on "{", if
forward-sexp followed by backward-sexp moves to a different spot,
especially given the above documentation.

Tom

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