dot/ercrc.el: Abstract out the alist augmentation machinery.

This actually was a pile of no fun at all, but it seems to work.

diff --git a/dot/ercrc.el b/dot/ercrc.el
index a84d63f..a539010 100644 (file)
--- a/dot/ercrc.el
+++ b/dot/ercrc.el
@@ -46,18 +46,53 @@ matches SERVER-REGEXP.")
   "*Alist of (SERVER-REGEXP ACCT PASSWD).
 Login details for claiming server admin rights.")
 
+(defun mdw-remprop-nondestructive (indic plist)
+  "Return a plist like PLIST, only without the first entry for INDIC.
+The PLIST is not itself modified."
+  (if (getf plist indic)
+      (let* ((head (cons nil nil))
+            (tail head))
+       (while (and plist (not (eq (car plist) indic)))
+         (let* ((i (pop plist)) (v (pop plist))
+                (vv (cons v nil)) (ii (cons i vv)))
+           (rplacd tail ii)
+           (setq tail vv)))
+       (rplacd tail (cddr plist))
+       (cdr head))
+    plist))
+
+(defmacro* mdw-pushnew-replace
+    (item place &rest keys &key (key '#'identity) &allow-other-keys)
+  "Add ITEM to the list PLACE, replacing any existing matching item.
+Specifically, any item in the list satisfying the test are removed
+\(nondestructively), and then the new ITEM is added to the front.
+
+Evaluation order for the keywords is a bit screwy: don't rely on it."
+  ;; `cl-setf-do-modify' returns a list (LETS STORE FETCH).
+  (let ((setf-things (cl-setf-do-modify place (cons 'list keys)))
+       (keyfn (gensym "key"))
+       (itemvar (gensym "item")))
+    `(let ((,keyfn ,key)
+          (,itemvar ,item)
+          ,@(car setf-things))
+       ,(cl-setf-do-store (cadr setf-things)
+                         `(cons ,itemvar
+                                (remove* (funcall ,keyfn ,itemvar)
+                                         ,(caddr setf-things)
+                                         :key ,keyfn
+                                         ,@(mdw-remprop-nondestructive
+                                            :key keys)))))))
+
 (defun mdw-define-bot-greeting (server bot greeting)
   "Define a new bot greeting."
-  (setq mdw-erc-auto-greet-bots-alist
-       (cons (list server bot greeting)
-             (remove* server mdw-erc-auto-greet-bots-alist
-                      :test #'string= :key #'car))))
+  (mdw-pushnew-replace (list server bot greeting)
+                      mdw-erc-auto-greet-bots-alist
+                      :test #'string= :key #'car))
 (defun mdw-add-ircop-credentials (server acct passwd)
   "Define a new set of `ircop' credentials."
-  (setq mdw-erc-ircop-alist
-       (cons (list server acct passwd)
-             (remove* server mdw-erc-ircop-alist
-                      :test #'string= :key #'car)))))
+  (mdw-pushnew-replace (list server acct passwd)
+                      mdw-erc-ircop-alist
+                      :test #'string= :key #'car))
 (load "~/.erc-auth.el")
 
 (defun mdw-assoc-regexp (regexp alist)