hook into change of position?

hook into change of position?

[troelskn]

Hi

I'm trying to hack together some elisp, and I need to somehow hook a
function callback up to be called whenever the position changes. Is
there an obvious way to do that?

--
thanks

Re: hook into change of position?

[Daniel Jensen]

troelskn <troelskn@gmail.com> writes:

> I'm trying to hack together some elisp, and I need to somehow hook a
> function callback up to be called whenever the position changes. Is
> there an obvious way to do that?

Depending on what you're trying to do, there are different options.

With post-command-hook, you can do something after every user command.
You'll have to check how point changed.

You can use an idle timer. Same thing here.

Text properties point-left and point-entered can be used to do
something for specific areas in the buffer.

Re: hook into change of position?

[troelskn]

On Jun 10, 2:35 pm, dan...@bigwalter.net (Daniel Jensen) wrote:
> Depending on what you're trying to do, there are different options.
Thanks. After some experiments, I ended up writing wrappers explicitly
for the functions, which I need to extend. I can't help feeling, that
there is some smarter way of accomplishing this, though.

For example:
(defun my-end-of-line (&optional arg)
  ""
  (interactive "p")
  (setq mark-active nil)
  (end-of-line arg)
  (my-hook-function))

I'm not even sure, that the (optional) argument `arg` will be passed
on correctly to the wrapped function `end-of-line`

--
troels

Re: hook into change of position?

[Daniel Jensen]

troelskn <troelskn@gmail.com> writes:

> Thanks. After some experiments, I ended up writing wrappers explicitly
> for the functions, which I need to extend. I can't help feeling, that
> there is some smarter way of accomplishing this, though.

It's not necessarily bad; many modes define their own movement commands.
You still haven't told exactly what you are doing, so I cannot tell.

> (defun my-end-of-line (&optional arg)
>   ""
>   (interactive "p")
>   (setq mark-active nil)
>   (end-of-line arg)
>   (my-hook-function))

Maybe this was only example code, but I'll point out anyway that it's in
bad style. Use descriptive names and write a documentation string, so
that one can at least guess what the function does.

> I'm not even sure, that the (optional) argument `arg` will be passed
> on correctly to the wrapped function `end-of-line`

What makes you think that? Did you try it?