Re: [HELP] (bug?) Saving a buffer without any conversion?

[storm@cua.dk (Kim F. Storm)]

Kenichi Handa <handa@m17n.org> writes:

> In article <5xk7h67k1b.fsf@kfs2.cua.dk>, storm@cua.dk (Kim F. Storm) writes:
> > He uses a process filter to "insert" the received strings to the
> > buffer like this [approximately]:
> 
> >         (defun filter (proc string)
> >           (with-current-buffer (process-buffer proc)
> >             (insert string)))
> 
> Ah!  Now I see what's going on.  If the coding system for
> proc is no-conversion or raw-text, STRING above is unibyte,
> thus, when inserted in a multibyte buffer, it is converted
> to the corresponding multibyte string.  This conversion
> converts all 0xA0..0xFF to Latin-1 (in Latin-1 lang. env.).


I see.  Now I understand it too ... 


> Yes.  And, instead of adding that, chaging this:
> ...
> to this:
> 
> > 	      :filter (lambda (proc string)
> > 			(with-current-buffer (get-buffer "temp.out")
> > 			  (insert (string-as-multibyte string))))
> 
> also produces the right result.

I think we need to write something about this somewhere.

E.g. add this to the doc string for `set-process-filter':

If the process' input coding system is no-conversion or raw-text, the
string argument to the filter function is a unibyte string; otherwise
it is a multibyte string.  Use `string-as-multibyte' on a unibyte
string before inserting it in a multibyte buffer.

Note: If the sole purpose of the filter is to insert received data
into a specific buffer, it is better NOT to define a process filter,
but instead set the process' buffer to that buffer.



> 
> Which is the better solution?  It depends on how the buffer
> is used later.  If it is just to save the received bytes in
> a file, using a unibyte buffer is better.  But, in that
> case, first of all, why is the process filter necessary?
> 

I don't know ... I didn't write the code :-)

In any case, I have just confirmed that if you DON'T use a filter
function, but rather relies on emacs itself to insert received data
into the buffer, it works nicely even with a multibyte buffer.

-- 
Kim F. Storm <storm@cua.dk> http://www.cua.dk