(defun wg-remove-workgroup-parameter (workgroup parameter)

  "Remove PARAMETER from WORKGROUP's parameters."

  (let ((workgroup (wg-get-workgroup workgroup)))

    (wg-flag-workgroup-modified workgroup)

    (wg-asetf (wg-workgroup-parameters workgroup) (wg-aremove it parameter))))

;; (defun wg-workgroup-local-value (variable &optional workgroup)

;;   "Return the value of VARIABLE in WORKGROUP.

;; WORKGROUP nil defaults to the current workgroup.  If there is no

;; current workgroup, or if VARIABLE does not have a workgroup-local

;; binding in WORKGROUP, resolve VARIABLE with `wg-session-local-value'."

;;   (let ((workgroup (wg-get-workgroup workgroup t)))

;;     (if (not workgroup) (wg-session-local-value variable)

;;       (let ((value (wg-workgroup-parameter workgroup variable 'default)))

;;         (if (not (eq value 'default)) value

;;           (wg-session-local-value variable))))))

(defun wg-workgroup-local-value (variable &optional workgroup)

  "Return the value of VARIABLE in WORKGROUP.

WORKGROUP nil defaults to the current workgroup.  If there is no

current workgroup, or if VARIABLE does not have a workgroup-local

binding in WORKGROUP, resolve VARIABLE with `wg-session-local-value'."

  (let ((workgroup (wg-get-workgroup workgroup t)))

    (if (not workgroup) (wg-session-local-value variable)

      (let* ((undefined (wg-gensym))

             (value (wg-workgroup-parameter workgroup variable undefined)))

        (if (not (eq value undefined)) value

          (wg-session-local-value variable))))))

(defalias 'wg-local-value 'wg-workgroup-local-value)

;;; workgroup associated buffers

(defun wg-workgroup-associated-buf-uids (workgroup)

  "Return a new list containing all of WORKGROUP's associated buf uids."

  (append (wg-workgroup-strong-buf-uids workgroup)

          (wg-workgroup-weak-buf-uids workgroup)))

(defun wg-workgroup-associated-bufs (workgroup)

  "Return a new list containing all of WORKGROUP's associated bufs."

  (delete nil (mapcar 'wg-find-buf-by-uid

                      (wg-workgroup-associated-buf-uids workgroup))))

(defun wg-workgroup-associated-buffers (workgroup &optional initial names)

  "Return a list of WORKGROUP's live associated buffers."

  (let ((assoc-bufs (wg-workgroup-associated-bufs workgroup)))

     (lambda (buffer) (wg-find-buffer-in-buf-list buffer assoc-bufs))

     (or initial (buffer-list)))))

(defun wg-workgroup-bufobj-association-type (workgroup bufobj)

  "Return BUFOBJ's association-type in WORKGROUP, or nil if unassociated."

  (let ((uid (wg-bufobj-uid-or-add bufobj)))

    (or (and (member uid (wg-workgroup-strong-buf-uids workgroup)) 'strong)

        (and (member uid (wg-workgroup-weak-buf-uids workgroup)) 'weak))))

(defun wg-workgroup-strongly-associate-bufobj (workgroup bufobj)

  "Strongly associate BUFOBJ with WORKGROUP."

  (let* ((uid (wg-bufobj-uid-or-add bufobj))

         (remp (wg-removef-p uid (wg-workgroup-weak-buf-uids workgroup)

                             :test 'string=))

         (addp (wg-pushnew-p uid (wg-workgroup-strong-buf-uids workgroup)

                             :test 'string=)))

    (when (or remp addp)

      (wg-flag-workgroup-modified workgroup)

      bufobj)))

(defun wg-workgroup-weakly-associate-bufobj (workgroup bufobj)

  "Weakly associate BUFOBJ with WORKGROUP."

  (let* ((uid (wg-bufobj-uid-or-add bufobj))

         (remp (wg-removef-p uid (wg-workgroup-strong-buf-uids workgroup)

                             :test 'string=))

         (addp (wg-pushnew-p uid (wg-workgroup-weak-buf-uids workgroup)

                             :test 'string=)))

    (when (or remp addp)

      (wg-flag-workgroup-modified workgroup)

      bufobj)))

(defun wg-workgroup-dissociate-bufobj (workgroup bufobj)

  "Dissociate BUFOBJ from WORKGROUP."

  (let* ((uid (wg-bufobj-uid-or-add bufobj))

         (rem1p (wg-removef-p uid (wg-workgroup-strong-buf-uids workgroup)

                              :test 'string=))

         (rem2p (wg-removef-p uid (wg-workgroup-weak-buf-uids workgroup)

                              :test 'string=)))

    (wg-awhen (or rem1p rem2p)

      (wg-flag-workgroup-modified workgroup)

      bufobj)))

(defun wg-workgroup-associate-bufobj (workgroup bufobj &optional weak)

  "Associate BUFOBJ with WORKGROUP.

WEAK non-nil means weakly associate it.  Otherwise strongly associate it."

  (if weak (wg-workgroup-weakly-associate-bufobj workgroup bufobj)

    (wg-workgroup-strongly-associate-bufobj workgroup bufobj)))

  "Return ID's KEY's value in `wg-buffer-list-filter-definitions'.

Lots of possible errors here because

`wg-buffer-list-filter-definitions' can be modified by the user."

  (let ((slot-num (case key (symbol 0) (indicator 1) (constructor 2))))

    (if (not slot-num)

        (unless noerror

          (error "`%S' is not a valid buffer-list-filter definition slot" key))

      (let* ((id (wg-get-buffer-list-filter-id-flexibly id))

             (entry (assq id (wg-local-value

                              'wg-buffer-list-filter-definitions))))

        (if (not entry)

            (unless noerror

              (error "`%S' is an undefined buffer-list-filter" id))

          (or (nth slot-num entry)

              (unless noerror

                (error "Slot `%S' is undefined in `%S's definition"

                       key id))))))))

(defun wg-filtered-buffer-list (&optional names workgroup bfl-id initial)

  "Return a filtered buffer-list from NAMES, WORKGROUP, BLF-ID and INITIAL.

NAMES non-nil means return a list of buffer-names instead of buffer objects.

WORKGROUP non-nil should be any workgroup identifier accepted by

`wg-get-workgroup'.

BLF-ID non-nil should be the identifier of a defined buffer-list-filter.

It defaults to `wg-get-buffer-list-filter-val'.

INITIAL non-nil should be an initial buffer-list to filter.  It defaults to

`wg-interesting-buffers'."

  (let ((buffer-list (funcall (wg-get-buffer-list-filter-val

                               (wg-get-buffer-list-filter-id-flexibly bfl-id)

                               'constructor)

                              (wg-get-workgroup workgroup)

                              (or initial (wg-interesting-buffers)))))

    (if names (mapcar 'wg-buffer-name buffer-list) buffer-list)))

;; buffer-list filters

(defun wg-buffer-list-filter-all (workgroup initial)

  "Return all buffers in INITIAL."

  initial)

(defun wg-buffer-list-filter-associated (workgroup initial)

  "Return only those buffers associated with WORKGROUP."

  (wg-workgroup-associated-buffers workgroup initial))

(defun wg-buffer-list-filter-unassociated (workgroup initial)

  "Return only those buffer unassociated with WORKGROUP."

  (let ((buffers (wg-workgroup-associated-buffers workgroup initial)))

;; buffer-list filtration utils

(defun wg-filter-buffer-list-by-regexp (regexp buffer-list)

  "Return only those buffers in BUFFER-LIST with names matching REGEXP."

                 buffer-list :key 'buffer-name))

(defun wg-filter-buffer-list-by-root-dir (root-dir buffer-list)

  "Return only those buffers in BUFFER-LIST visiting files undo ROOT-DIR."

                 buffer-list :key 'buffer-file-name))

(defun wg-filter-buffer-list-by-major-mode (major-mode buffer-list)

  "Return only those buffers in BUFFER-LIST in major-mode MAJOR-MODE."

                 buffer-list :key 'wg-buffer-major-mode))

;; Example custom buffer-list-filters

(defun wg-buffer-list-filter-irc (workgroup buffer-list)

  "Return only those buffers in BUFFER-LIST with names starting in \"#\"."

  (wg-filter-buffer-list-by-regexp "^#" buffer-list))

(defun wg-buffer-list-filter-home-dir (workgroup buffer-list)

  "Return only those buffers in BUFFER-LIST visiting files under ~/."

  (wg-filter-buffer-list-by-root-dir "~/" buffer-list))

(defun wg-buffer-list-filter-elisp (workgroup buffer-list)

  "Return only those buffers in BUFFER-LIST in `emacs-lisp-mode'."

  (wg-filter-buffer-list-by-major-mode 'emacs-lisp-mode buffer-list))

(defun wg-buffer-list-filter-home-dir->elisp (workgroup buffer-list)

  "Example of chaining buffer-list filters.

This returns all buffers under \"~/\" that are also in `emacs-lisp-mode'."

  (wg-buffer-list-filter-elisp

   nil (wg-buffer-list-filter-home-dir nil buffer-list)))

;; buffer-list-filter context

(defun wg-buffer-list-filter-order (command)

  "Return WORKGROUP's buffer-list-filter order for COMMAND, or a default."

  (let ((bfo (wg-local-value 'wg-buffer-list-filter-order-alist)))

    (or (wg-aget bfo command) (wg-aget bfo 'default))))

(defmacro wg-prior-mapping (mode command)

  "Return whatever COMMAND would call if MODE wasn't on."

  `(or (let (,mode) (command-remapping ,command)) ,command))

(defun wg-filter-buffer-list-p ()

  "Return the current workgroup when buffer-list-filters are on."

  (and workgroups-mode wg-buffer-list-filtration-on (wg-current-workgroup t)))

(defmacro wg-with-buffer-list-filters (command &rest body)

  "Create buffer-list filter context for COMMAND, and eval BODY.

Binds `wg-current-buffer-list-filter-id' in BODY."

  (declare (indent 1))

  (wg-with-gensyms (order status)

    `(let* ((wg-previous-minibuffer-contents nil)

            (,order (wg-buffer-list-filter-order ,command)))

       (catch 'wg-result

         (while 'your-mom

(defun wg-workgroup-save-wconfig (workgroup wconfig)

  "Add WCONFIG to WORKGROUP's saved wconfigs.  WCONFIG must have

a name.  If there's already a wconfig with the same name in

WORKGROUP's saved wconfigs, replace it."

  (let ((name (wg-wconfig-name wconfig)))

    (unless name (error "Attempt to save a nameless wconfig"))

    (setf (wg-workgroup-modified workgroup) t)

    (wg-asetf (wg-workgroup-saved-wconfigs workgroup)

              (cons wconfig (remove* name it

                                     :key 'wg-wconfig-name

                                     :test 'string=)))))

(defun wg-workgroup-kill-saved-wconfig (workgroup wconfig-or-name)

  "Delete WCONFIG-OR-NAME from WORKGROUP's saved wconfigs.

WCONFIG-OR-NAME is resolved with `wg-workgroup-get-saved-wconfig'."

  (wg-when-let ((wconfig (wg-workgroup-get-saved-wconfig

                          workgroup wconfig-or-name)))

    (wg-asetf (wg-workgroup-saved-wconfigs workgroup) (remq wconfig it)

              (wg-workgroup-modified workgroup) t)))

;;; garbage collection

;; update buf list

(defun wg-update-buffer-in-buf-list (&optional buffer)

  "Update BUFFER's corresponding buf in `wg-buf-list'.

BUFFER nil defaults to `current-buffer'."

  (let ((buffer (or buffer (current-buffer))))

    (wg-when-let ((uid (wg-buffer-uid buffer))

                  (old-buf (wg-find-buf-by-uid uid))

                  (new-buf (wg-buffer-to-buf buffer)))

      (setf (wg-buf-uid new-buf) (wg-buf-uid old-buf))

      (wg-asetf (wg-buf-list) (cons new-buf (remove old-buf it))))))

(defun wg-update-buf-list (&optional buffer-list)

  "Update all bufs in `wg-buf-list' corresponding to buffers in BUFFER-LIST."

  (mapc 'wg-update-buffer-in-buf-list (or buffer-list (buffer-list))))

;; gc buf uids

(defun wg-workgroup-gc-buf-uids (workgroup)

  "Remove buf uids from WORKGROUP that have no referent in `wg-buf-list'."

  (wg-asetf (wg-workgroup-strong-buf-uids workgroup)

            (wg-workgroup-weak-buf-uids workgroup)

(defun wg-gc-buf-uids ()

  "Remove from all workgroups those buf uids that have no referent in `wg-buf-list'."

  (mapc 'wg-workgroup-gc-buf-uids (wg-workgroup-list)))

;; gc bufs

(defun wg-wtree-buf-uids (wtree)

  "Return a new list of the buf uids of all wins in wtree."

  (wg-flatten-wtree wtree 'wg-win-buf-uid))

(defun wg-wtree-unique-buf-uids (wtree)

  "Return a list of the unique buf uids of all wins in wtree."

  (remove-duplicates (wg-wtree-buf-uids wtree) :test 'string=))

(defun wg-wconfig-buf-uids (wconfig)

  "Return WCONFIG's wtree's `wg-wtree-buf-uids'."

  (wg-wtree-unique-buf-uids (wg-wconfig-wtree wconfig)))

(defun wg-workgroup-base-wconfig-buf-uids (workgroup)

  "Return a new list of all unique buf uids in WORKGROUP's working wconfig."

  (wg-wconfig-buf-uids (wg-workgroup-base-wconfig workgroup)))

(defun wg-workgroup-saved-wconfigs-buf-uids (workgroup)

  "Return a new list of all unique buf uids in WORKGROUP's base wconfig."

  (reduce 'wg-string-list-union

          (wg-workgroup-saved-wconfigs workgroup)

          :key 'wg-wconfig-buf-uids))

(defun wg-workgroup-all-wconfig-buf-uids (workgroup)

  "Return a new list of all unique buf uids in WORKGROUP's wconfigs."

  (union (wg-workgroup-base-wconfig-buf-uids workgroup)

         (wg-workgroup-saved-wconfigs-buf-uids workgroup)

         :test 'string=))

(defun wg-workgroup-all-buf-uids (workgroup)

  "Return a new list of all unique buf uids in WORKGROUP."

  (reduce 'wg-string-list-union

          (list (wg-workgroup-base-wconfig-buf-uids workgroup)

                (wg-workgroup-saved-wconfigs-buf-uids workgroup)

                (wg-workgroup-associated-buf-uids workgroup))))

(defun wg-session-all-buf-uids (&optional session)

  "Return a new list of all unique buf uids in SESSION.

SESSION nil defaults to `wg-current-session'."

  (reduce 'wg-string-list-union

          (wg-session-workgroup-list (or session (wg-current-session)))

          :key 'wg-workgroup-all-buf-uids))

(defun wg-buffer-list-all-uids (&optional buffer-list)

  "Return a list of the uids of all buffers in BUFFER-LIST in

which `wg-buffer-uid' is locally bound.

BUFFER-LIST nil defaults to `buffer-list'."

  (delq nil (mapcar 'wg-buffer-uid (or buffer-list (buffer-list)))))

(defun wg-all-buf-uids (&optional session buffer-list)

  "Return the union of `wg-session-all-buf-uids' and `wg-buffer-list-all-uids'."

  (union (wg-session-all-buf-uids session)

         (wg-buffer-list-all-uids buffer-list)

         :test 'string=))

(defun wg-gc-bufs ()

  "gc bufs from `wg-buf-list' that are no longer needed."

  (let ((all-buf-uids (wg-all-buf-uids)))

    (wg-asetf (wg-buf-list)

                             :key 'wg-buf-uid))))

;; FIXME: Duplicate buf names probably shouldn't be allowed.  An unrelated error

;; causes two *scratch* buffers to be present, triggering the "uids don't match"

;; error.  Write something to remove bufs with duplicate names.

(defun wg-perform-session-maintenance ()

  "Perform various maintenance operations on the current Workgroups session."

  (wg-update-current-workgroup-working-wconfig)

  (wg-update-all-base-wconfigs)

  (wg-gc-bufs)

  (wg-gc-buf-uids)

  (wg-update-buf-list))

;; session consistency testing

(defun wg-session-uids-consistent-p ()

  "Return t if there are no duplicate bufs or buf uids in the wrong places,

nil otherwise."

  (and (every (lambda (wg)

                (not (wg-dups-p (wg-workgroup-associated-buf-uids wg)

                                :test 'string=)))

              (wg-workgroup-list))

       (not (wg-dups-p (wg-buf-list) :key 'wg-buf-uid :test 'string=))

       (not (wg-dups-p (wg-workgroup-list) :key 'wg-workgroup-uid :test 'string=))))

;;; workgroup restoration

(defun wg-restore-workgroup-associated-buffers-internal (workgroup)

  "Restore all the buffers associated with WORKGROUP that can be restored."

  (save-window-excursion

    (delete nil (mapcar 'wg-restore-buffer

                        (wg-workgroup-associated-bufs workgroup)))))

(defun wg-restore-workgroup (workgroup)

  "Restore WORKGROUP in `selected-frame'."

  (when wg-restore-associated-buffers

    (wg-restore-workgroup-associated-buffers-internal workgroup))

  (let (wg-flag-modified)

    (wg-restore-wconfig-undoably

     (wg-workgroup-working-wconfig workgroup) t)))