save-excursion or (let ((here (point)))

save-excursion or (let ((here (point)))

[Lennart Borgman]

I got some problem with flickering when using (let ((here (point))) +
(goto-char here). I am not sure why.

What is the best way to just save the point? Should save-excursion be
used instead or is it perhaps slow?

Re: save-excursion or (let ((here (point)))

[Stefan Monnier]

> I got some problem with flickering when using (let ((here (point))) +
> (goto-char here). I am not sure why.

If there's flickering, it means there's redisplay.  You need to figure
out where/when that happens.


        Stefan

Re: save-excursion or (let ((here (point)))

[Lennart Borgman]

On Fri, Jul 24, 2009 at 9:28 PM, Stefan Monnier<monnier@iro.umontreal.ca> wrote:
>> I got some problem with flickering when using (let ((here (point))) +
>> (goto-char here). I am not sure why.
>
> If there's flickering, it means there's redisplay.  You need to figure
> out where/when that happens.


Thanks. Sorry. I should have said "I can see the point moving and then
moving back sometimes". I am not sure if that can be avoided and that
is what I want to know.

Re: save-excursion or (let ((here (point)))

[Miles Bader]

Lennart Borgman <lennart.borgman@gmail.com> writes:
>> If there's flickering, it means there's redisplay.  You need to figure
>> out where/when that happens.
>
> Thanks. Sorry. I should have said "I can see the point moving and then
> moving back sometimes". I am not sure if that can be avoided and that
> is what I want to know.

That means you're doing redisplay inside the let body; you need to
figure out where/when that happens.

-Miles

-- 
Electricity, n. The cause of all natural phenomena not known to be caused by
something else.

Re: save-excursion or (let ((here (point)))

[Lennart Borgman]

On Sat, Jul 25, 2009 at 4:21 AM, Miles Bader<miles@gnu.org> wrote:
> Lennart Borgman <lennart.borgman@gmail.com> writes:
>>> If there's flickering, it means there's redisplay.  You need to figure
>>> out where/when that happens.
>>
>> Thanks. Sorry. I should have said "I can see the point moving and then
>> moving back sometimes". I am not sure if that can be avoided and that
>> is what I want to know.
>
> That means you're doing redisplay inside the let body; you need to
> figure out where/when that happens.


Thanks, but how do I know if a function triggers redisplay?

It looks to me that this might happen while calling `message' when it
displays more than one line, but I am not sure.

Re: save-excursion or (let ((here (point)))

[martin rudalics]

 > Thanks, but how do I know if a function triggers redisplay?

You could try to bind `inhibit-redisplay' to t around calls and
see whether the flickering goes away.

martin

Re: save-excursion or (let ((here (point)))

[Stefan Monnier]

> Thanks, but how do I know if a function triggers redisplay?

Very few functions cause redisplay.  The main ones are the ones that
wait (sleep, sit-for, read, ...).


        Stefan

Re: save-excursion or (let ((here (point)))

[Lennart Borgman]

On Sat, Jul 25, 2009 at 4:44 PM, Stefan Monnier<monnier@iro.umontreal.ca> wrote:
>> Thanks, but how do I know if a function triggers redisplay?
>
> Very few functions cause redisplay.  The main ones are the ones that
> wait (sleep, sit-for, read, ...).


Thanks, the problem disappeared. I am not sure why. I don't think any
of the functions above where involved (I don't belive I am calling
them here).

I suspect that it had something to do with either error handling (I
was rewriting some code and the way I do that causes a lot of
errors...) or calling `message' with long lines that does not fit on
one line (these were trace messages used during the rewrite).