Changing side margins in specific mode changes side margins for all buffers

Changing side margins in specific mode changes side margins for all buffers

[hack writer]

Hi everyone,

I use

(add-hook 'window-configuration-change-hook (lambda () (set-window-margins
(car (get-buffer-window-list (current-buffer) nil t)) 29 29)))

to set side margins in a specific emacs mode. But when I open further
buffers, no matter what mode, all buffers use the same side margins. How I
can achieve, that only my specific mode buffers use side margins but all
other buffers not?

(add-hook 'window-configuration-change-hook (lambda () (set-window-margins
(car (get-buffer-window-list (current-buffer) nil t)) 29 29))
'make-it-local)

didn't work.

Regards

hack

Re: Changing side margins in specific mode changes side margins for all buffers

[hack writer]

@Stefan

Works like a charm. Thank you very much!

I found this code somewhere on stackoverflow.com.

Regards,

hack

Re: Changing side margins in specific mode changes side margins for all buffers

[Stefan Monnier]

> Works like a charm. Thank you very much!
> I found this code somewhere on stackoverflow.com.

Could you try and find it again, so we can fix it there?


        Stefan

Re: Changing side margins in specific mode changes side margins for all buffers

[Emanuel Berg]

hack writer <GNU@bookhacker.org> writes:

> (add-hook 'window-configuration-change-hook (lambda
> () (set-window-margins (car (get-buffer-window-list
> (current-buffer) nil t)) 29 29)))
>
> to set side margins in a specific emacs mode.
> But when I open further buffers, no matter what
> mode, all buffers use the same side margins.
> How I can achieve, that only my specific mode
> buffers use side margins but all other buffers not?
>
> (add-hook 'window-configuration-change-hook (lambda
> () (set-window-margins (car (get-buffer-window-list
> (current-buffer) nil t)) 29 29)) 'make-it-local)
>
> didn't work.

No - this whole idea isn't good. It will slow down the
interactive feel to test at each window configuration
change what mode it is. And the "slowing down" is
going in the wrong direction - something specific
(your mode) will slow down all of Emacs!

What kind of mode do you have? I think there is a much
better way to do this, but it is difficult to tell
without knowing what you want to do.

-- 
underground experts united
http://user.it.uu.se/~embe8573

Re: Changing side margins in specific mode changes side margins for all buffers

[Stefan Monnier]

> (add-hook 'window-configuration-change-hook (lambda () (set-window-margins
> (car (get-buffer-window-list (current-buffer) nil t)) 29 29)))

Your code is unreadable.  For your own sake, lay it out clearly:

   (add-hook 'window-configuration-change-hook
             (lambda ()
               (set-window-margins (car (get-buffer-window-list
                                         (current-buffer) nil t))
                                   29 29)))

Which sets up a global hook, and then

> (add-hook 'window-configuration-change-hook (lambda () (set-window-margins
> (car (get-buffer-window-list (current-buffer) nil t)) 29 29))
> 'make-it-local)

turns into

   (add-hook 'window-configuration-change-hook
             (lambda ()
               (set-window-margins (car (get-buffer-window-list
                                         (current-buffer) nil t))
                                   29 29))
             'make-it-local)

where you see that you pass `make-it-local' as third argument.  And if
you check `C-h f add-hook RET' you'll see that the third arg is called
APPEND, and it's the *fourth* arg which is called LOCAL.  So you just
need to add a nil as third argument.

BTW, where did you get (car (get-buffer-window-list (current-buffer) nil t))?
`C-h v window-configuration-change-hook' says:

   The buffer-local part is run once per window, with the relevant window
   selected; while the global part is run only once for the modified frame,

so since "the relevant window" is already selected, you don't need to
look for it.  You can either use (selected-window) or more simply nil
since the default for set-window-margins is to use the selected window.

IOW:

   (add-hook 'window-configuration-change-hook
             (lambda () (set-window-margins nil 29 29))
             nil 'local)


-- Stefan

Re: Changing side margins in specific mode changes side margins for all buffers

[Emanuel Berg]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>    (add-hook 'window-configuration-change-hook
>              (lambda ()
>                (set-window-margins (car (get-buffer-window-list
>                                          (current-buffer) nil t))
>                                    29 29))
>              'make-it-local)
>
> where you see that you pass `make-it-local' as third
> argument. And if you check `C-h f add-hook RET'
> you'll see that the third arg is called APPEND, and
> it's the *fourth* arg which is called LOCAL. So you
> just need to add a nil as third argument.

Aha, the HOOK is local, not the window-margins!
Then what I said is incorrect. It won't do what I said
(which is good).

>> Works like a charm. Thank you very much! I found
>> this code somewhere on stackoverflow.com.
>
> Could you try and find it again, so we can fix
> it there?

Wow, you are dedicated! Cred. Maybe we should all post
our Elisp on stackoverflow just to have you correct it
:)

-- 
underground experts united
http://user.it.uu.se/~embe8573