mu4e: implement :hide-if-no-unread

Make mu4e-maildir-shortcut and mu4e-bookmarks understand a property
:hide-if-no-unread~, which hides the maildir/bookmark from the main-view
if there are no unread messages which the corresponding query.

NEWS.org

@@ -91,6 +91,10 @@
     automatically translate; this depends on the ~pcre2el~ package which the user
     should install when using regular expression-addresses.
 
+  - ~mu4e-maildir-shortcuts~ and ~mu4e-bookmarks~ now understand a property
+    ~:hide-if-no-unread~, which hides the maildir/bookmark from the main-view if
+    there are no unread messages which the corresponding query.
+
 * 1.12 (released on February 24, 2024)
 
 ** Some highlights

mu4e/mu4e-bookmarks.el

@@ -65,6 +65,10 @@ item must be unique among `mu4e-bookmarks' and
 `mu4e-maildir-shortcuts'.
 - `:hide' - if t, the bookmark is hidden from the main-view and
 speedbar.
+- `:hide-if-no-unread' - if t, the shortcut is hidden from
+   the main-view if it contains are no unread messages.
+
+You can also use:
 - `:hide-unread' - do not show the counts of
 unread/total number of matches for the query in the main-view.
 This can be useful if a bookmark uses a very slow query.

mu4e/mu4e-folders.el

@@ -105,9 +105,13 @@ Each of the list elements is a plist with at least:
 Optionally, you can add the following:
 `:name' - name of the maildir to be displayed in main-view.
 `:hide'  - if t, the shortcut is hidden from the main-view.
+`:hide-if-no-unread' - if it t, the shortcut is hidden from
+ the main-view if it contains no unread messages.
+
+ You can also use:
 `:hide-unread' - do not show the counts of unread/total number
  of matches for the maildir in the main-view, and is implied
-from `:hide'.
+ from `:hide'.
 
 For backward compatibility, an older form is recognized as well:
 

mu4e/mu4e-helpers.el

@@ -593,6 +593,33 @@ This is mu4e's version of Emacs 29's `plistp'."
   (let ((len (proper-list-p object)))
     (and len (zerop (% len 2)))))
 
+(defun mu4e-plist-do (func plist)
+  "Apply FUNC to each element in PLIST.
+FUNC receives to arguments: the key and its value."
+  (when plist
+    (funcall func (car plist) (cadr plist))
+    (mu4e-plist-do func (cddr plist))))
+
+(defun mu4e-plist-remove (plist prop)
+  "Remove PROP from PLIST.
+Returns the updated PLIST."
+  ;; inspired by org-plist-delete
+  (let (p)
+    (while plist
+      (if (not (eq prop (car plist)))
+          (setq p (plist-put p (car plist) (nth 1 plist))))
+      (setq plist (cddr plist)))
+    p))
+
+(defun mu4e-plist-remove-nils (plist)
+  "Remove all properties with value nil from PLIST."
+  (let (p)
+    (while plist
+      (when (cadr plist)
+        (setq p (plist-put p (car plist) (cadr plist))))
+      (setq plist (cddr plist)))
+    p))
+
 (defun mu4e--message-hide-headers ()
   "Hide headers based on the `message-hidden-headers' variable.
 This is mu4e's version of the post-emacs-28 `message-hide-headers',

mu4e/mu4e-main.el

@@ -223,10 +223,11 @@ for aligning them."
   (mapconcat
    (lambda (item)
      (cl-destructuring-bind
-         (&key hide name key favorite query &allow-other-keys) item
+         (&key name key favorite query
+               hide hide-if-no-unread unread &allow-other-keys) item
        ;; hide items explicitly hidden, without key or wrong category.
-       (if hide
+       (if (or hide (and hide-if-no-unread (zerop unread)))
-           ""
+           "" ;; hide
          (let ((item-info
                 ;; note, we have a function for the binding,
                 ;; and perhaps a different one for the lambda.
@@ -410,7 +411,8 @@ instead."
   (unless (file-directory-p smtpmail-queue-dir)
     (mu4e-error "`smtpmail-queue-dir' does not exist"))
   (setq smtpmail-queue-mail (not smtpmail-queue-mail))
-  (message (concat "Outgoing mail will now be "
+  (mu4e-message
+   (concat "Outgoing mail will now be "
            (if smtpmail-queue-mail "queued" "sent directly")))
   (unless (or (eq mu4e-split-view 'single-window)
               (not (buffer-live-p (get-buffer mu4e-main-buffer-name))))

mu4e/mu4e-query-items.el

@@ -228,25 +228,21 @@ bookmark or maildir."
              (list
               :name         name
               :query        query
-              :key          (plist-get item :key)
               :count        count
               :unread       unread
               :delta-count  (- count baseline-count)
               :delta-unread delta-unread)))
        ;; remember the *effective* query too; we don't really need it, but
        ;; useful for debugging.
-       (unless (string= query effective-query)
+       (setq value (plist-put value :effective-query effective-query))
-         (plist-put value :effective-query effective-query))
+       (setq value (plist-put value :maildir maildir))
-       ;;for matching maildir shortcuts
+       ;; copy some other items from item.
-       (when maildir (plist-put value :maildir maildir))
+       (mu4e-plist-do (lambda (k v)
+                        (when (memq k '(:key :maildir :hide :hide-if-no-unread
+                                             :hide-unread))
+                          (setq value (plist-put value k v)))) item)
        ;; nil props bring me discomfort
-       (when (plist-get item :favorite)
+       (mu4e-plist-remove-nils value)))
-         (plist-put value :favorite t))
-       (when (plist-get item :hide)
-         (plist-put value :hide t))
-       (when (plist-get item :hide-unread)
-         (plist-put value :hide-unread t))
-       value))
    data))
 
 (defun mu4e-query-items (&optional type)

mu4e/mu4e.texi

@@ -840,12 +840,15 @@ instance:
      :query "list:mu-discuss.googlegroups.com AND date:7d..now"))
 @end lisp
 
-There are optional keys @t{:hide} to hide the bookmark from the main menu, but
+There are optional keys @code{:hide} to hide the bookmark or maildirs from the
-still have it available (using @key{b})) and @t{:hide-unread} to avoid
+main menu, but still have it available (using @key{b})), and
-generating the unread-number; that can be useful if you have bookmarks for slow
+@code{:hide-if-no-unread} to hide it if there are no unread messages.
-queries. Note that @t{:hide-unread} is implied when the query is not a string;
+
-this for the common case where the query function involves some user input,
+To customize the display, there is also @code{:hide-unread} to avoid generating
-which would be disruptive in this case.
+the unread-number; that can be useful if you have bookmarks for slow queries.
+Note that @code{:hide-unread} is implied when the query is not a string; this
+for the common case where the query function involves some user input, which
+would be disruptive in this case.
 
 There is also the optional @code{:favorite} property, which at most one bookmark
 should have; this bookmark is highlighted in the main view, and its
@@ -2180,18 +2183,36 @@ be instructive:
   "List of pre-defined queries that are shown on the main screen.
 
 Each of the list elements is a plist with at least:
-:name  - the name of the query
+`:name'  - the name of the query
-:query - the query expression
+`:query' - the query expression string or function
-:key   - the shortcut key.
+`:key'   - the shortcut key (single character)
 
-Optionally, you add the following:
+Optionally, you can add the following:
-:hide  - if t, bookmark is hidden from the main-view and speedbar.
+
-:hide-unread - do not show the counts of unread/total number
+- `:favorite' - if t, monitor the results of this query, and make
- of matches for the query. This can be useful if a bookmark uses
+it eligible for showing its status in the modeline. At most
- a very slow query. :hide-unread is implied from :hide.
+one bookmark should have this set to t (otherwise the _first_
-"
+bookmark is the implicit favorite). The query for the `:favorite'
+item must be unique among `mu4e-bookmarks' and
+`mu4e-maildir-shortcuts'.
+- `:hide' - if t, the bookmark is hidden from the main-view and
+speedbar.
+- `:hide-if-no-unread' - if t, the shortcut is hidden from
+   the main-view if it contains are no unread messages.
+
+You can also use:
+- `:hide-unread' - do not show the counts of
+unread/total number of matches for the query in the main-view.
+This can be useful if a bookmark uses a very slow query.
+
+`:hide-unread' is implied from `:hide'.
+
+Note: for efficiency, queries used to determine the unread/all
+counts do not discard duplicate or unreadable messages. Thus, the
+numbers shown may differ from the number you get from a normal
+query."
   :type '(repeat (plist))
-  :group 'mu4e)
+  :group 'mu4e-bookmarks)
 @end lisp
 
 You can replace these or add your own items, by putting in your
@@ -2303,14 +2324,18 @@ maildirs (folders) very quickly --- for example, getting to the @t{/lists}
 folder only requires you to type @kbd{jl}, then change to @t{/work} with
 @kbd{jw}.
 
-While in queries you need to quote folder names (maildirs) with spaces in
+While in queries you need to quote folder names (maildirs) with spaces in them,
-them, you should @emph{not} quote them when used in
+you should @emph{not} quote them when used in @code{mu4e-maildir-shortcuts},
-@code{mu4e-maildir-shortcuts}, since @t{mu4e} does that automatically for you.
+since @t{mu4e} does that automatically for you.
 
 The very same shortcuts are used by @kbd{M-x mu4e-mark-for-move} (default
 shortcut @key{m}); so, for example, if you want to move a message to the
 @t{/archive} folder, you can do so by typing @kbd{ma}.
 
+For further customization, you can use @code{:hide}, @code{:hide-if-no-unread},
+@code{:hide-unread} and @code{:favorite} properties, just like for
+@ref{Bookmarks and Maildirs}.
+
 @node Other search functionality
 @section Other search functionality