Re: Reading file in emacs

[Pascal J. Bourguignon]

Qiang Guo <mcknight0219@gmail.com> writes:
> I'm wondering if there is a way to read the content of files, say, to a
> variable rather than a buffer ? Of course, one way to do
> this is first read file into buffer and then edit the
> buffer. 

If you need to have the content of a file in a variable, then you
could bind a buffer to a variable:

(let ((my-buffer (current-buffer)))
  (with-temp-buffer
     (insert "hi")
     (insert (with-current-buffer my-buffer (buffer-substring 1 3)))
     (list my-buffer (buffer-substring (point-min) (point-max)))))

--> (#<buffer *followup to Qiang Guo on gnu.emacs.help*> 
     #("hiNe" 2 4 (fontified t face message-header-name)))

The point is that the data structure optimized in emacs to store long
sequences of characters (or "bytes" since in emacs characters are
integers), is the buffer.  If you try to manipulate strings, you may
find it's slower than doing the equivalent in a buffer. (At least,
that's the common wisdom about emacs buffers vs strings, you could
benchmark it).


> Here comes my second question, how to process file
> in a byte-by-byte fashion, for instance, instead of editing
> a line of text, I'd like to edit directly their binary
> representations ?


-- 
__Pascal Bourguignon__                     http://www.informatimago.com/