1 files changed, 19 insertions, 3 deletions

diff --git a/lisp/ibuf-macs.el b/lisp/ibuf-macs.el
index 3e026de2a08..6ef83594e0c 100644
--- a/lisp/ibuf-macs.el
+++ b/lisp/ibuf-macs.el
@@ -71,7 +71,8 @@ During evaluation of body, bind `it' to the value returned by TEST."
 ;; (put 'ibuffer-save-marks 'lisp-indent-function 0)
 
 ;;;###autoload
-(defmacro* define-ibuffer-column (symbol (&key name inline props) &rest body)
+(defmacro* define-ibuffer-column (symbol (&key name inline props
+                                               summarizer) &rest body)
   "Define a column SYMBOL for use with `ibuffer-formats'.
 
 BODY will be called with `buffer' bound to the buffer object, and
@@ -81,7 +82,9 @@ will be `buffer'.
 If NAME is given, it will be used as a title for the column.
 Otherwise, the title will default to a capitalized version of the
 SYMBOL's name.  PROPS is a plist of additional properties to add to
-the text, such as `mouse-face'.
+the text, such as `mouse-face'.  And SUMMARIZER, if given, is a
+function which will be passed a list of all the strings in its column;
+it should return a string to display at the bottom.
 
 Note that this macro expands into a `defun' for a function named
 ibuffer-make-column-NAME.  If INLINE is non-nil, then the form will be
@@ -90,8 +93,14 @@ change its definition, you should explicitly call
 `ibuffer-recompile-formats'."
   (let* ((sym (intern (concat "ibuffer-make-column-"
                               (symbol-name symbol))))
-         (bod-1 `(with-current-buffer buffer
+         (bod-2 `(with-current-buffer buffer
                    ,@body))
+         (bod-1 (if summarizer
+                    `(car
+                      (push ,bod-2
+                            ,(intern (format "ibuffer-summary-for-column-%s"
+                                             name))))
+                  bod-2))
          (bod (if props
                  `(propertize
                    ,bod-1
@@ -106,6 +115,13 @@ change its definition, you should explicitly call
             ,(if (stringp name)
                  name
                (capitalize (symbol-name symbol))))
+       ,(if summarizer
+            `(put (quote ,sym) 'ibuffer-column-summarizer
+                  (quote ,summarizer)))
+       ,(if summarizer
+            `(defvar ,(intern (format "ibuffer-summary-for-column-%s"
+                                      name))
+               nil))
        :autoload-end)))
 ;; (put 'define-ibuffer-column 'lisp-indent-function 'defun)