Re: Adding `#' at each new line with text until the end of the file

[Merciadri Luca <Luca.Merciadri@student.ulg.ac.be>]

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pjb@informatimago.com (Pascal J. Bourguignon) writes:

> Merciadri Luca <Luca.Merciadri@student.ulg.ac.be> writes:
>
>> pjb@informatimago.com (Pascal J. Bourguignon) writes:
>>
>>>> Sure, but, as I explained in my previous message, it does not even
>>>> modify the Sayings file. Why?
>>>
>>> Because you didn't instruct the program to modify the file.
>>> Read the documentation of insert, for example.  Does it mention files?
>>> What does insert modify?
>> Insert modifies the current buffer, according to the manual. Or
>> find-file loads its arg into a buffer. So, if find-file loads its arg
>> into the *current* buffer, insert should modify the current buffer,
>> that is, `Sayings'.
>
> (list
>     (progn (find-file "/tmp/Sayings")
>            (buffer-name (current-buffer)))
>     (progn (find-file "/mnt/Sayings")
>            (buffer-name (current-buffer))))
> --> ("Sayings" "Sayings<2>")
>
> Here you have two files, named "/tmp/Sayings" and "/mnt/Sayings", and
> when opening them at the same time,  we get "Sayings" and "Sayings<2>"
> as buffer names.
>
> Clearly, the buffer names are not entirely independant from the file
> names, but it should be obvious from the example, that there's two
> name spaces and two different kind of entities.  A buffer named "X" is
> not a file name "X".
>
> So to repeat what you wrote above:
>
> - find-file (or find-file-noselect) loads the contents of a  _file_
>   into a _buffer_.
>
> - insert modifies the contents of a _buffer_.
>
> When  you do only these to action what happens to the _file_?
Nothing, actually. That's the problem.

>>> Here is a macro that could be useful:
>
> Here with find-file-noselect as it has been advised (not tested):
>
> (require 'cl)
> (defmacro* with-file (file-and-options &body body)
>   "Processes BODY with a buffer on the given file.
> DO:              find-file or find-file-literally, process body, and
>                  optionally save the buffer and kill it.
>                  save is not done if body exits exceptionnaly.
>                  kill is always done as specified.
> FILE-AND-OPTION: either an atom evaluated to a path,
>                  or (path &key (save t) (kill t) (literal nil))
> "
>   (if (atom file-and-options)
>       `(with-file (,file-and-options) ,@body)
>       ;; destructuring-bind is broken, we cannot give anything else than nil
>       ;; as default values:
>       (destructuring-bind (path &key (save nil savep) (kill nil killp)
>                                 (literal nil literalp))
>           file-and-options
>         (unless savep (setf save t))
>         (unless killp (setf kill t))
>         `(unwind-protect
>               (progn
>                 (find-file-noselect ,path t ,literal)
>                 (prog1 (save-excursion ,@body)
>                   ,(when save `(save-buffer 1))))
>            ,(when kill
>                   `(kill-buffer (current-buffer)))))))
>
>> Thanks. I'll keep it.
Thanks.

- -- 
Merciadri Luca
See http://www.student.montefiore.ulg.ac.be/~merciadri/
- -- 

Nobody leaves us, we only leave others.
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