with-fetch-letter-sequence

Arguments: (mailbox &rest args) &body body

with-fetch-letter-sequence prepares for retrieval of a letter in a memory efficient manner. It is useful in cases where it is inefficient or impossible to store a letter in memory as a string. This macro is implemented for pop mailboxes only.

args are arguments suitable for a call to fetch-letter.

Within body, fetch-letter-sequence calls may be made to retrieve the first and subsequent chunks of text from the desired letter.

with-fetch-letter-sequence calls cannot be nested.

Example:

;; Download and save an arbitrarily large message into a file
;; for later processing.
(with-open-file (f "letterfile" :direction :output :if-does-not-exist :create)
  (with-pop-connection ("localhost" :user "joe" :password "secret")
    ;; download letter number 12
    (with-fetch-letter-sequence (mb 12)
      (let ((buffer (make-string 4096))
            endpos)
        (until (end-of-letter-p mb)
	  (setf endpos (fetch-letter-sequence mb buffer))
          (write-sequence buffer f :end endpos))))))

See also fetch-letter-sequence and end-of-letter-p.

See imap.htm for more information.

Copyright (c) 1998-2006, Franz Inc. Oakland, CA., USA. All rights reserved.
Documentation for Allegro CL version 7.0. This page is new in the 7.0 release.
Created 2005.9.20.