Re: get-byte

[Kenichi Handa]

In article <address@hidden>, Stefan Monnier <address@hidden> writes:

> I'm not opposed to `get-byte' being implemented in C.  I just think it
> should be implementable as

>   (defun get-byte (&optional pos string)
>     (let ((ch (if string (aref string (or pos 0))
>                 (char-after pos))))
>       (or (encode-char ch 'binary)
>           (error "Not an ASCII nor an 8-bit character: %d" ch))))

`binary' is not a character set, and even if you change it
to `eight-bit', it can't be used for unibyte buffer/string
because, for instance, (encode-char 128 'eight-bit) is nil.

Or, are you proposing to create `binary' charset to make the
above work?

> Given that, in most cases where you'd use get-byte you could replace it
> with either (encode-char (char-after POS) 'binary)
> or (encode-char (aref STRING POS) 'binary).  It may still be
> significantly slower than a direct C implementation of get-byte, but it
> is the right functionality to provide (i.e. get-byte is only there for
> optimization purposes) and in some cases get-byte is not an option
> (e.g. in cases such as (mapcar (lambda (c) (... (encode-char c 'binary)
> ..)) <string>)).

Do you have a concrete example in which you need some result
as a list?  I think, most of the case, we don't need such a
list, and thus we can have this version:
  (dotimes (i (length <string>))
    (... (get-byte i string) ...))

---
Kenichi Handa
address@hidden