Re: [External] : Passing buffers to function in elisp

[Michael Heerdegen <michael_heerdegen@web.de>]

Petteri Hintsanen <petterih@iki.fi> writes:

>   (defun emms-info-native--read-and-decode-ogg-page (filename offset)
>     (with-temp-buffer
>       (set-buffer-multibyte nil)
>       (insert-file-contents-literally filename
>                                       nil
>                                       offset
>                                       (+ offset
>                                          emms-info-native--ogg-page-size))
>       (emms-info-native--decode-ogg-page (buffer-string))))
> [...]
>
>   (defun emms-info-native--decode-ogg-packets (filename packets)
>     (let ((num-packets 0)
>           (offset 0)
>           (stream (vector)))
>       (while (< num-packets packets)
>         (let ((page (emms-info-native--read-and-decode-ogg-page filename
>                                                                 offset)))
>           (cl-incf num-packets (or (plist-get page :num-packets) 0))
>           (cl-incf offset (plist-get page :num-bytes))
>           (setq stream (vconcat stream (plist-get page :stream)))
>       stream))

If `emms-info-native--read-and-decode-ogg-page' is called very often
(hundreds of times or more), it's probably better to use one single
buffer instead of a fresh temp buffer every single time.  Using temp
buffers creates quite a bunch of garbage IME.

Michael.