setting of local variable in derived mode

setting of local variable in derived mode

[Chris Wittern]

Hi Emacs users,

I am defining a derived mode as described in the elisp manual under "Example
Major Modes". I am doing the following:


(define-derived-mode mandoku-view-mode org-mode "mandoku-view"
  "a mode to view mandoku files
  \\{mandoku-view-mode-map}"
  (setq case-fold-search nil)
  (set (make-local-variable 'tab-with) 30)
)


I expect this to set the tab-width in all buffers with this mode to the
value 30.  However, the value stays at 8 as before.  Could some kind soul
please tell me what I am doing wrong?

All the best,

Chris

Re: setting of local variable in derived mode

[Stefan Monnier]

> I expect this to set the tab-width in all buffers with this mode to the
> value 30.  However, the value stays at 8 as before.  Could some kind soul
> please tell me what I am doing wrong?

Please carefully read the output of `C-h v tab-width`.
And/or search the web to figure out what `tab-width` means compared to
what you presumably want (the distance the cursor moves when you hit the
TAB key).


        Stefan

Re: setting of local variable in derived mode

[Stefan Monnier]

> I expect this to set the tab-width in all buffers with this mode to the
> value 30.  However, the value stays at 8 as before.

What makes you think it's set at 8?  What did you do to check that?
Also: take a look at http://www.pement.org/emacs_tabs.htm


        Stefan

Re: setting of local variable in derived mode

[Chris Wittern]

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

> 
> > I expect this to set the tab-width in all buffers with this mode to the
> > value 30.  However, the value stays at 8 as before.
> 
> What makes you think it's set at 8?  What did you do to check that?
> Also: take a look at http://www.pement.org/emacs_tabs.htm

The output of C-h v tab-width tells me that it's value is 8.
And yes, I know what it does and see it correctly if I manually set this to
30.  So somehow the command when invoking the mode is not correctly executed
I assume. 

All the best,

Christian

Re: setting of local variable in derived mode

[Stefan Monnier]

>> > I expect this to set the tab-width in all buffers with this mode to the
>> > value 30.  However, the value stays at 8 as before.
>> What makes you think it's set at 8?  What did you do to check that?
> The output of C-h v tab-width tells me that it's value is 8.

Hmm... sorry for assuming this was the usual trivial problem.
Indeed, you bumped into another trivial problem:

  (set (make-local-variable 'tab-with) 30)
                                 ^^^^
                                   d

-- Stefan

Re: setting of local variable in derived mode

[Chris Wittern]

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


> Hmm... sorry for assuming this was the usual trivial problem.
> Indeed, you bumped into another trivial problem:
> 
>   (set (make-local-variable 'tab-with) 30)
>                                  ^^^^
>                                    d
Ooops, indeed!  Thanks for pointing this out.  This should do the trick and
save my day.

All the best,

Chris