Re: beginning-of-defun (again)

[David Kastrup <dak@gnu.org>]

Andreas Röhler <andreas.roehler@online.de> writes:

>  On 29.10.2015 14:31, David Kastrup wrote:
>> Andreas Röhler<andreas.roehler@online.de>  writes:
>>
>>>   On 29.10.2015 13:46, Alan Mackenzie wrote:
>>>> Hello, Andreas.
>>>>
>>>> On Thu, Oct 29, 2015 at 12:24:48PM +0100, Andreas Röhler wrote:
>>>>>     Hi guys,
>>>>> maybe it's time to have a reasonable default-behavior of
>>>>> beginning-of-defun in Emacs Lisp.
>>>>> IMO there is no reason for stuff like
>>>>> open-paren-in-column-0-is-defun-start
>>>> Unfortunately, there is.  Setting it to nil ensures accurate recognition
>>>> of non-nested parens,
>>> Sorry, Alan, but if there is no syntax expecting a start in column 0,
>>> there is no reason to assume that.
>>>
>>> Relying on such means working in some cases, in other not. You won't
>>> want that.
>> If Emacs becomes too slow for useful work otherwise, that's no
>> alternative to it sometimes making assumptions leading to bad
>> highlighting.
>>
>
> Where it was proven Emacs is slow WRT an reasonable implementation, if
> such a thing doesn't exist?

It's not more than 2 years ago or so that I had
open-paren-in-column-0-is-defun-start set to nil for a while.  I reset
it eventually since it caused holdups in scheme-mode (which, being based
on lisp-mode, is one of the most modern modes) when working on LilyPond.
Possibly also for working on Elisp.

I don't remember the details completely, but I do remember that I had
usability reasons to reset it again to its default value.

> AFAIK the current buggy one predates parse-partial-sexp and that part
> was never reconsidered WRT pps since.

parse-partial-sexp is not exactly new.

-- 
David Kastrup