Noam Postavsky <npostavs@gmail.com> writes:

> On Fri, 5 Apr 2019 at 22:22, Eric Abrahamsen <eric@ericabrahamsen.net> wrote:
>
>> >> "nnml:\343\203\206\343\202\271\343\203\210"
>
>> >> "nnml:ã\203\206ã\202¹ã\203\210"
>
>> > Are you maybe looking for decode-coding-string?
>
>> No, unfortunately -- that would make everything much easier. Eventually
>> the idea will be to decode the strings into plain utf-8-emacs, but for
>> now I'm stuck keeping them in this weird half-state. I literally need a
>> conversion between the two versions above.
>
> Oh, I missed which two string you meant. It seems that evaluating the
> 1st string with C-x C-e prints the second string in the *Messages*
> buffer (I initially thought they were the same string), but
> printing/inserting it doesn't work the same. The message code prints
> one character at a time, and indeed, inserting one character at a time
> in lisp works too:
>
> (let ((s "nnml:\343\203\206\343\202\271\343\203\210"))
>   (with-temp-buffer
>     (mapc #'insert s)
>     (buffer-string)))
>
> The following shorter expression also seem to work:
>
> (apply #'string (string-to-list "nnml:\343\203\206\343\202\271\343\203\210"))
>
> And apply #'unibyte-string goes back again:
>
> (let* ((s1 "nnml:\343\203\206\343\202\271\343\203\210")
>        (s2 (apply #'string (string-to-list s1))))
>   (apply #'unibyte-string (string-to-list s2)))
>
> I can't say I completely understand why all this works though.

No, I spoke too soon. It must be another case of a string that doesn't
quite look like what it actually is. The string that looks like
"nnml:\343\203" etc must be something different: when I run your example
using a typed-in version of the string it behaves correctly, but when I
run it with the actual string I'm working with, the apply #'string
doesn't change it.

You can get the string I'm fighting with by saving the attached file and
running:

(with-temp-buffer
  (set-buffer-multibyte t)
  (let ((coding-system-for-read 'raw-text))
    (insert-file-contents "active")
    (goto-char (point-min))
    (symbol-name (read (current-buffer)))))
    
I'm trying to turn that into something that looks like
"nnml:ã\203\206ã\202¹ã\203\210"

Thanks,
Eric