Re: How to execute code on cursor move

[Suvayu Ali <fatkasuvayu+linux@gmail.com>]

Hi Drew,

On Sat, Jul 13, 2013 at 06:26:24AM -0700, Drew Adams wrote:
> > > I want to check a text property and display in the minibuffer depending
> > > on context (in my case, on an org-link).
> > >
> > > (add-hook 'post-command-hook
> > > 	  (lambda()
> > > 	    (if (eq (get-text-property (point) 'face) 'org-link)
>                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > Is using the post-command-hook a good idea?
> > 
> > No, because it slows down Emacs's _every_ command.
> > 
> > > Is there something better?
> > 
> > There are the 'point-entered' and 'point-left' text properties.  Make
> > sure they cover the buffer positions where you want to display the
> > message in the echo area, and the rest should be easy.
> 
> Remember too that the `face' property can be a cons of faces or face
> attributes.  So you might not want to test for `org-link' using only `eq'.
> IOW, you might want something like this, to check for the presence of
> face `org-link':
> 
> (let ((face  (get-text-property (point) 'face)))
>   (or (eq 'org-link face)
>       (and (consp face)  (memq 'org-link face))))
> 

I actually saw something very similar in Org mode source but didn't
quite follow everything, so I "simplified" it to what you see
above.  :-p

Thank you very much for the pointer.  Now I understand :).  

Cheers,

-- 
Suvayu

Open source is the future. It sets us free.