(defun assoc-default (key alist &optional test default)
  "Find object KEY in a pseudo-alist ALIST.
ALIST is a list of conses or objects.  Each element (or the element's car,
if it is a cons) is compared with KEY by evaluating (TEST (car elt) KEY).
If that is non-nil, the element matches;
then `assoc-default' returns the element's cdr, if it is a cons,
or DEFAULT if the element is not a cons.

If no element matches, the value is nil.
If TEST is omitted or nil, `equal' is used."
  (let (found (tail alist) value)
    (while (and tail (not found))
      (let ((elt (car tail)))
	(when (funcall (or test 'equal) (if (consp elt) (car elt) elt) key)
	  (setq found t value (if (consp elt) (cdr elt) default))))
      (setq tail (cdr tail)))
    value))


(defun make-temp-file (prefix &optional dir-flag suffix)
  "Create a temporary file.
The returned file name (created by appending some random characters at the
end of PREFIX, and expanding against the return value of `temp-directory' if
necessary), is guaranteed to point to a newly created empty file.  You can
then use `write-region' to write new data into the file.

If DIR-FLAG is non-nil, create a new empty directory instead of a file.

If SUFFIX is non-nil, add that at the end of the file name.

This function is analagous to mkstemp(3) under POSIX, avoiding the race
condition between testing for the existence of the generated filename (under
POSIX with mktemp(3), under Emacs Lisp with `make-temp-name') and creating
it."
  (let ((umask (default-file-modes))
	(temporary-file-directory (temp-directory))
	file)
    (unwind-protect
	(progn
	  ;; Create temp files with strict access rights.  It's easy to
	  ;; loosen them later, whereas it's impossible to close the
	  ;; time-window of loose permissions otherwise.
	  (set-default-file-modes #o700)
	  (while (condition-case ()
		     (progn
		       (setq file
			     (make-temp-name
			      (expand-file-name prefix
						temporary-file-directory)))
		       (if suffix
			   (setq file (concat file suffix)))
		       (if dir-flag
			   (make-directory file)
			 (write-region "" nil file nil 'silent nil 'excl))
		       nil)
		   (file-already-exists t))
	    ;; the file was somehow created by someone else between
	    ;; `make-temp-name' and `write-region', let's try again.
	    nil)
	  file)
      ;; Reset the umask.
      (set-default-file-modes umask))))