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iterating over a list while removing elements


From: lee
Subject: iterating over a list while removing elements
Date: Wed, 19 Mar 2014 12:39:43 +0100
User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3.50 (gnu/linux)

Hi,

what is the defined behaviour when you iterate over a list and remove
elements from that very list?  For example:


(defsubst multisearch-directory-ref-p (dots)
  "Return t when the string DOTS ends in a directory reference."
  (or
   (string-match "\\.$" dots)
   (string-match "\\.\\.$" dots)))

(defun multisearch-make-files-list (directory)
  "Return a list of files in DIRECTORY, with directory references
and directories removed."
  (let ((files-list (directory-files directory t)))
    (dolist (entry files-list files-list)
      (unless (and
               (not (multisearch-directory-ref-p entry))
               (file-directory-p entry)
               (file-readable-p entry))
        (setq files-list (delete entry files-list))))))


Surprisingly, this /appears/ to work.  Can I take that for granted, or
is this a stupid thing to do?  It`s like someone pulling the chair
you`re about to sit on from underneath you ...


-- 
Knowledge is volatile and fluid.  Software is power.



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