Re: Tabs and Spaces

[Chris Gordon-Smith]

Pascal J. Bourguignon <pjb@informatimago.com> wrote:
> use.address@my.homepage.invalid (Chris Gordon-Smith) writes:
> 
>> Pascal J. Bourguignon <pjb@informatimago.com> wrote:
>>> use.address@my.homepage.invalid (Chris Gordon-Smith) writes:
>>> 
>>>> Hello All
>>>>
>>>> I have recenly started using emacs for programming, after years using 
>>>> KDevelop. One problem I have is indenting code. I have my own indentation 
>>>> style. and ideally I would like to setup emacs to support it 
>>>> automatically. 
>>>> However, in the short term I'll settle for having emacs convert a TAB 
>>>> keypress into the correct number of spaces to fill whitespace up to the 
>>>> next tabstop.
>>>>
>>>> At the moment I have
>>>>
>>>> (global-set-key (kbd "TAB") 'self-insert-command) 
>>>>
>>>> in my .emacs to force insertion of a tab, but I have to keep invoking 
>>>> untabify manually (otherwise my code looks misaligned when I upload it to 
>>>> Google Code).
>>>>
>>>> Can anyone help.
>>> 
>>> You shouldn't insert TAB, this is very bad.  At the very least, you
>>> may compute the number of spaces you need to insert and insert them
>>> rather.
>> Yes, that's what I would like to do. Can you suggest how to do this. Do I 
>> need to put something in my .emacs file. What would it look like?
>>
>>> 
>>> But depending on the language you use, a different mode will be used
>>> to edit your source and each mode may provide its own indenting rules.
>>> 
>>> In the case of Lisp, you may add a indent-function property to the
>>> plist of the operator name.
>>> 
>>> In the case of C, you may customize the variable: c-offsets-alist. See
>>> also: c-style-alist ; perhaps there's already a style defined that
>>> you'll like.
> 
> 
> In my post, there was a subliminal question, but it didn't reach your
> consciousness, I'm sorry.  Here it is:

It wasn't really a question, and the fact that you had mentioned that the 
solution to the problem might be language dependent did register with me.

I think its a pity that you chose to answer in what appears to be a rather 
rude manner.
> 
>   What programming language do you use?

C++.  But I had already established before my original post that the 
standard emacs indenting would not suit me. Perhaps I should have mentioned 
this.

> 
> Depending on the answer you give, you may well have nothing to program.
> Otherwise, you could do something like this:
> 
> (defconst +space+ 32 "ASCII code for the space character")
> 
> (defun my-language/indent-line ()
>   (interactive) 
>   (let ((where (let ((m (make-marker))) (set-marker m (point)) m))
>         (indent (my-language/get-indent-from-some-parsing-around (point))))
>      (beginning-of-line)
>      (looking-at "^[ \t]*")
>      (delete-region (beginning-of-line) (match-end))
>      (goto-char (beginning-of-line))
>      (insert (make-string indent +space+))
>      (goto-char where)
>      (set-marker where nil)))
> 
> 
> (local-set-key (kbd "TAB") 'my-language/indent-line)
> 
> 
> Of course, all the difficulty (or simplicity, depends on your language)
> is in implementing my-language/get-indent-from-some-parsing-around.
> 
> 

Thanks for this.
I'll need to read it and understand it before I use it, but it looks like a 
good starting point.

Chris Gordon-Smith
www.simsoup.info