setting the mode of a buffer

setting the mode of a buffer

[lee]

Hi,

how would I set the mode of a buffer along the lines of ...


(with-current-buffer buffer (set-auto-mode t))


... but by setting a particular mode rather calling a function to set
modes which would be automatically set.

The above works, though it seems to be rather inefficient.  I have tried
with (set-auto-mode-0) and got errors because a hook involved with the
mode I was trying to set couldn´t find its function.


In the end, what I´m trying to achieve is to be able to reload a mode
after it has been modified.  To reload it, I´m using (unload-feature),
and that disables the mode for all buffers for which it is enabled.  It
also magically removes an entry in auto-mode-alist for this mode.

When the mode is reloaded, I have to enable it for all relevant buffers
manually.  To avoid having to do this, I´ve finally written a function
that goes through the buffer-list and enables the mode for particular
buffers.  This function uses (set-auto-mode), in lack of a better
alternative.

Perhaps I´m going all wrong about this and there is a better way to
reload a mode?


-- 
Knowledge is volatile and fluid.  Software is power.

Re: setting the mode of a buffer

[Joost Kremers]

lee wrote:
> Perhaps I´m going all wrong about this and there is a better way to
> reload a mode?

It's possible you don't need to reload the mode at all. This is Lisp,
after all, not C. If you change a function definition, you only need to
eval it (eval-defun, bound to C-M-x in emacs-lisp-mode), or you can
recompile the entire file.

If you change a defvar, eval'ing that won't load the new value, but you
can simply use setq to set the new value.

IME it's hardly never necessary to actually unload a feature and then
reload it.


-- 
Joost Kremers                                   joostkremers@fastmail.fm
Selbst in die Unterwelt dringt durch Spalten Licht
EN:SiS(9)

Re: setting the mode of a buffer

[lee]

Joost Kremers <joost.m.kremers@gmail.com> writes:

> lee wrote:
>> Perhaps I´m going all wrong about this and there is a better way to
>> reload a mode?
>
> It's possible you don't need to reload the mode at all. This is Lisp,
> after all, not C. If you change a function definition, you only need to
> eval it (eval-defun, bound to C-M-x in emacs-lisp-mode), or you can
> recompile the entire file.
>
> If you change a defvar, eval'ing that won't load the new value, but you
> can simply use setq to set the new value.
>
> IME it's hardly never necessary to actually unload a feature and then
> reload it.

The mode is byte-compiled --- it mainly provides some syntax
highlighting.  Mostly, changes are to defcustoms to add another keyword
for the highlighting.

When I make a change, I byte-compile again.  From there on, I need some
way to apply the changes.  So far, I´ve been reloading the mode to
achieve this.

Are you saying that changes are magically applied by recompiling?  Or
should I use 'M-x eval-defun my-mode' to apply them after recompiling?
And when I do so, wouldn´t emacs figure that it already knows the mode
because it´s already loaded and continue to use the previous version?


-- 
Knowledge is volatile and fluid.  Software is power.

Re: setting the mode of a buffer

[Joost Kremers]

lee wrote:
> Joost Kremers <joost.m.kremers@gmail.com> writes:
> The mode is byte-compiled --- it mainly provides some syntax
> highlighting.  Mostly, changes are to defcustoms to add another keyword
> for the highlighting.

Reevaluating a defcustom will normally reset the value of the variable,
so there's no need to unload and reload the file. 

> When I make a change, I byte-compile again.  From there on, I need some
> way to apply the changes.  So far, I´ve been reloading the mode to
> achieve this.

Yes, but you do not need to unload it first. If you reload the file, the
new definitions will replace the old ones.

> Are you saying that changes are magically applied by recompiling?  Or
> should I use 'M-x eval-defun my-mode' to apply them after recompiling?
> And when I do so, wouldn´t emacs figure that it already knows the mode
> because it´s already loaded and continue to use the previous version?

You do need to reload it, compiling alone is not enough.

IME defvar definitions aren't always updated when you reload a file, but
that's easily remedied with a setq in an *ielm* buffer. (Do `M-x ielm'
if you don't know about ielm. It's a god send.)


-- 
Joost Kremers                                   joostkremers@fastmail.fm
Selbst in die Unterwelt dringt durch Spalten Licht
EN:SiS(9)

Re: setting the mode of a buffer

[Stefan Monnier]

> Reevaluating a defcustom will normally reset the value of the variable,
> so there's no need to unload and reload the file. 

C-h f defcustom

   [...]
   :initialize
   	VALUE should be a function used to initialize the
   	variable.  It takes two arguments, the symbol and value
   	given in the `defcustom' call.  The default is
   	`custom-initialize-reset'.
   [...]

C-h f custom-initialize-reset

   [...]
   The value is either the symbol's current value
    (as obtained using the `:get' function), if any,
   [...]

So, no, re-evaluating a defcustom will typically leave the variable at its
old value.

M-: (progn (defcustom sm-t 1 "hhaha") (defcustom sm-t 2 "hhaha") sm-t) RET

returns 1, not 2.  IOW, it works more like defvar than like defconst.


        Stefan

Re: setting the mode of a buffer

[lee]

Joost Kremers <joost.m.kremers@gmail.com> writes:

> lee wrote:

> [...]
>> When I make a change, I byte-compile again.  From there on, I need some
>> way to apply the changes.  So far, I´ve been reloading the mode to
>> achieve this.
>
> Yes, but you do not need to unload it first. If you reload the file, the
> new definitions will replace the old ones.

>> Are you saying that changes are magically applied by recompiling?  Or
>> should I use 'M-x eval-defun my-mode' to apply them after recompiling?
>> And when I do so, wouldn´t emacs figure that it already knows the mode
>> because it´s already loaded and continue to use the previous version?
>
> You do need to reload it, compiling alone is not enough.

Hm, yes, I have made another mode yesterday, and re-compiling and
reloading it and C-x C-e to redefine functions worked fine.

> IME defvar definitions aren't always updated when you reload a file, but
> that's easily remedied with a setq in an *ielm* buffer. (Do `M-x ielm'
> if you don't know about ielm. It's a god send.)

Wow, ielm is really good to know, thanks!


-- 
Knowledge is volatile and fluid.  Software is power.

Re: setting the mode of a buffer

[lee]

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

>> Reevaluating a defcustom will normally reset the value of the variable,
>> so there's no need to unload and reload the file. 
>
> C-h f defcustom
>
>    [...]
>    :initialize
>    	VALUE should be a function used to initialize the
>    	variable.  It takes two arguments, the symbol and value
>    	given in the `defcustom' call.  The default is
>    	`custom-initialize-reset'.
>    [...]
>
> C-h f custom-initialize-reset
>
>    [...]
>    The value is either the symbol's current value
>     (as obtained using the `:get' function), if any,
>    [...]
>
> So, no, re-evaluating a defcustom will typically leave the variable at its
> old value.
>
> M-: (progn (defcustom sm-t 1 "hhaha") (defcustom sm-t 2 "hhaha") sm-t) RET
>
> returns 1, not 2.  IOW, it works more like defvar than like defconst.

Awesome --- it means I just have to do it right and use functions to set
up things and don`t need to unload the mode anymore :)

I got this mode from somewhere quite a while ago, and I think it isn`t
done right.  There isn`t anything to disable it, either.


-- 
Knowledge is volatile and fluid.  Software is power.

Re: setting the mode of a buffer

[Joost Kremers]

Stefan Monnier wrote:
> So, no, re-evaluating a defcustom will typically leave the variable at its
> old value.

Sorry, I should have mentioned that I meant reevaluating the defcustom
with C-M-x (`eval-defun'). Other methods (including reloading the file)
indeed do not.


-- 
Joost Kremers                                   joostkremers@fastmail.fm
Selbst in die Unterwelt dringt durch Spalten Licht
EN:SiS(9)