Re: should search ring contain duplicates?

[storm@cua.dk (Kim F. Storm)]

David Kastrup <dak@gnu.org> writes:

> What is the rationale for making this a macro?

It's named ...-push :-)

> Sure, you need to quote history in the call then, but it seems like
> the trouble for a macro is not really warranted.

You're right, so let's change it to a defun.

But then, to reduce confusion, the name should be `add-to-history',
and the sequence of args changed to match the interface of add-to-list.


(defun add-to-history (history-var newelt &optional maxelt)
  "Add NEWELT to the history list stored in the variable HISTORY-VAR.
If MAXELT is non-nil, it specifies the maximum length of the history.
Otherwise, the maximum history length is the value of the `history-length'
property on symbol HISTORY-VAR, if set, or the value of the `history-length'
variable.
Remove duplicates of NEWELT unless `history-delete-duplicates' is nil."
  (unless maxelt
    (setq maxelt (or (get history-var 'history-length)
		     history-length)))
  (let ((history (symbol-value history-var)))
    (if history-delete-duplicates
	(setq history (delete newelt history)))
    (setq history (cons newelt history))
    (when (integerp maxelt)
      (if (= 0 maxelt)
	  (setq history nil)
	(if (> (length history) maxelt)
	    (setcdr (nthcdr (1- maxelt) history) nil))))
    (set history-var history)))

-- 
Kim F. Storm <storm@cua.dk> http://www.cua.dk