simple function to prepend a string to a file

simple function to prepend a string to a file

[ken]

Often I want to put the string "<!-- -*- coding: utf-8; -*- -->\n" at
the top of the current buffer.  However, I don't want to lose my place
(the point) or any defined region.  Optimally, such a function would
know the mode of the current buffer and enclose the string in the
mode-appropriate comment characters.  Is there such a function?  If not
how would one code it?

Thanks for your solutions.

-- 
"To make an apple pie from scratch,
first create the universe."
        -- Carl Sagan

Re: simple function to prepend a string to a file

[harven]

ken <gebser@mousecar.com> writes:

> Often I want to put the string "<!-- -*- coding: utf-8; -*- -->\n" at
> the top of the current buffer.  However, I don't want to lose my place
> (the point) or any defined region.  Optimally, such a function would
> know the mode of the current buffer and enclose the string in the
> mode-appropriate comment characters.  Is there such a function?  If not
> how would one code it?
>
> Thanks for your solutions.

The following seems to work.

(defun my-header ()
  "put a commented header at the beginning of the buffer"
  (interactive)
  (save-excursion
    (beginning-of-buffer)
    (let ((start (point)))
      (insert "-*- coding: utf-8; -*-")
      (comment-region start (point))
      (newline))))

Re: simple function to prepend a string to a file

[Johan Bockgård]

harven <harven@free.fr> writes:

>     (beginning-of-buffer)

 "Don't use this command in Lisp programs!
  (goto-char (point-min)) is faster and avoids clobbering the mark."

Re: simple function to prepend a string to a file --> SOLUTION

[ken]

On 04/17/2009 10:10 AM harven wrote:
> ken <gebser@mousecar.com> writes:
> 
>> Often I want to put the string "<!-- -*- coding: utf-8; -*- -->\n" at
>> the top of the current buffer.  However, I don't want to lose my place
>> (the point) or any defined region.  Optimally, such a function would
>> know the mode of the current buffer and enclose the string in the
>> mode-appropriate comment characters.  Is there such a function?  If not
>> how would one code it?
>>
>> Thanks for your solutions.
> 
> The following seems to work.
> 
> (defun my-header ()
>   "put a commented header at the beginning of the buffer"
>   (interactive)
>   (save-excursion
>     (beginning-of-buffer)
>     (let ((start (point)))
>       (insert "-*- coding: utf-8; -*-")
>       (comment-region start (point))
>       (newline))))
> 

On 04/17/2009 12:28 PM Johan Bockgård wrote:
> harven <harven@free.fr> writes:
>
>>     (beginning-of-buffer)
>
>  "Don't use this command in Lisp programs!
>   (goto-char (point-min)) is faster and avoids clobbering the mark."
>

Fantastic, guys!  Thanks!!  Surprisingly to myself, my code was pretty
close to yours.  But I was missing crucial syntax and never would have
gotten it without you.  Here's our final version.  It does everything
right (that I can see).  I found that "(newline)" was unnecessary, so
took it out.  Counter-intuitive, that.


(defun utf-decl-prepend ()
  "Prepend to current buffer UTF declaration within comment."
  (interactive)
  (save-excursion
    (goto-char (point-min))
    (let ((start (point)))
      (insert "-*- coding: utf-8; -*-")
      (comment-region start (point)))))

Re: simple function to prepend a string to a file --> SOLUTION

[harven]

ken <gebser@mousecar.com> writes:

> (defun utf-decl-prepend ()
>   "Prepend to current buffer UTF declaration within comment."
>   (interactive)
>   (save-excursion
>     (goto-char (point-min))
>     (let ((start (point)))
>       (insert "-*- coding: utf-8; -*-")
>       (comment-region start (point)))))

(point-min) goes to the beginning of the accessible part of the
buffer, if the buffer is narrowed. I think it's better to really go at
the start of the buffer. This is a minor point though. Here is another
version, which is a bit shorter.

(defun utf-decl-prepend ()
   "Prepend to current buffer UTF declaration within comment."
   (interactive)
   (save-excursion
     (goto-char 1)
     (insert "-*- coding: utf-8; -*-")
     (comment-region 1 (point))
     (newline)))

The final newline is not needed in lisp mode or tex mode, where a
single delimiter is used for commenting. It is needed in c-mode or
html-mode however. I don't understand why. In these languages, a closing tag
ends the comment region, this may be the reason.

Re: simple function to prepend a string to a file --> SOLUTION

[Johan Bockgård]

harven <harven@free.fr> writes:

> (point-min) goes to the beginning of the accessible part of the
> buffer, if the buffer is narrowed.

(goto-char 1) does the same.

Re: simple function to prepend a string to a file --> SOLUTION

[harven]

bojohan+news@dd.chalmers.se (Johan Bockgård) writes:

> harven <harven@free.fr> writes:
>
>> (point-min) goes to the beginning of the accessible part of the
>> buffer, if the buffer is narrowed.
>
> (goto-char 1) does the same.

Ack ! Then I don't know why I used (goto-char (point-min))
instead of (goto-char 1) all these years.