Allow switching to more than one buffer (#861).

* helm-utils.el (helm-switch-to-buffer): Removed, use switch-to-buffer instead.
(helm-switch-to-buffers,
helm-switch-to-buffers-other-window): New.

* helm-source.el: Update type buffer.
* helm-buffers.el: Update keymap, use switch-to-buffer.
* helm-apt.el : Use switch-to-buffer.
* helm-emms.el: Use switch-to-buffer.
* helm-files.el: Use switch-to-buffer.
* helm-gentoo.el: Use switch-to-buffer.
* helm-grep.el: Use switch-to-buffer.
* helm-ring.el: Use switch-to-buffer.

helm-aliases.el

@@ -505,8 +505,6 @@
 (make-obsolete 'helm-c-bookmark-run-jump-other-window 'helm-bookmark-run-jump-other-window "1.5.1")
 (defalias 'helm-c-elisp-library-scan-list 'helm-elisp-library-scan-list)
 (make-obsolete 'helm-c-elisp-library-scan-list 'helm-elisp-library-scan-list "1.5.1")
-(defalias 'helm-c-switch-to-buffer 'helm-switch-to-buffer)
-(make-obsolete 'helm-c-switch-to-buffer 'helm-switch-to-buffer "1.5.1")
 (defalias 'helm-c-bookmark-man-setup-alist 'helm-bookmark-man-setup-alist)
 (make-obsolete 'helm-c-bookmark-man-setup-alist 'helm-bookmark-man-setup-alist "1.5.1")
 (defalias 'helm-c-etags-find-tag-file-directory 'helm-etags-find-tag-file-directory)

helm-apt.el

@@ -200,7 +200,7 @@ package name - description."
 (defun helm-apt-cache-show-1 (package)
   (let* ((command (format helm-apt-show-command package))
          (buf     (get-buffer-create "*helm apt show*")))
-    (helm-switch-to-buffer buf)
+    (switch-to-buffer buf)
     (unless (string= package helm-apt-show-current-package)
       (let ((inhibit-read-only t))
         (erase-buffer)

helm-buffers.el

@@ -203,7 +203,7 @@ Only buffer names are fuzzy matched when this is enabled,
                (if mjm
                    (with-current-buffer buffer (funcall mjm))
                    (set-buffer-major-mode buffer))
-               (helm-switch-to-buffer buffer))))))
+               (switch-to-buffer buffer))))))
 
 (defvar ido-temp-list)
 (defvar ido-ignored-list)
@@ -535,7 +535,7 @@ If REGEXP-FLAG is given use `query-replace-regexp'."
           for buf in bufs
           do
           (save-window-excursion
-            (helm-switch-to-buffer buf)
+            (switch-to-buffer buf)
             (save-excursion
               (let ((case-fold-search t))
                 (goto-char (point-min))
@@ -648,7 +648,7 @@ If REGEXP-FLAG is given use `query-replace-regexp'."
   "Run switch to other window action from `helm-source-buffers-list'."
   (interactive)
   (with-helm-alive-p
-    (helm-quit-and-execute-action 'switch-to-buffer-other-window)))
+    (helm-quit-and-execute-action 'helm-switch-to-buffers-other-window)))
 
 (defun helm-buffer-switch-other-frame ()
   "Run switch to other frame action from `helm-source-buffers-list'."
@@ -714,7 +714,7 @@ If REGEXP-FLAG is given use `query-replace-regexp'."
 (defun helm-buffers-list-persistent-action (candidate)
   (if current-prefix-arg
       (helm-buffers-persistent-kill candidate)
-    (helm-switch-to-buffer candidate)))
+    (switch-to-buffer candidate)))
 
 (defun helm-ediff-marked-buffers (_candidate &optional merge)
   "Ediff 2 marked buffers or CANDIDATE and `helm-current-buffer'.
@@ -794,7 +794,7 @@ displayed with the `file-name-shadow' face if available."
 (define-helm-type-attribute 'buffer
   `((action
      . ,(helm-make-actions
-         "Switch to buffer" 'helm-switch-to-buffer
+         "Switch to buffer" 'switch-to-buffer
          (lambda () (and (locate-library "popwin") "Switch to buffer in popup window"))
          'popwin:popup-buffer
          "Switch to buffer other window `C-c o'" 'switch-to-buffer-other-window

helm-emms.el

@@ -62,7 +62,7 @@
         (emms-stream-add-bookmark name url (string-to-number fd) type)
         (emms-stream-save-bookmarks-file)
         (emms-stream-quit)
-        (helm-switch-to-buffer cur-buf)))))
+        (switch-to-buffer cur-buf)))))
 
 (defun helm-emms-stream-delete-bookmark (_candidate)
   "Delete emms-streams bookmarks from helm."

helm-files.el

@@ -729,7 +729,7 @@ See `helm-find-files-eshell-command-on-file-1' for more info."
                         (format "cd '%s'" helm-ff-default-directory))
                        (eshell-send-input))))
     (if (get-buffer "*eshell*")
-        (helm-switch-to-buffer "*eshell*")
+        (switch-to-buffer "*eshell*")
       (call-interactively 'eshell))
     (unless (get-buffer-process (current-buffer))
       (funcall cd-eshell))))
@@ -2097,7 +2097,7 @@ If a prefix arg is given or `helm-follow-mode' is on open file."
              (make-directory image-dired-dir))
            (image-dired-display-image candidate)
            (message nil)
-           (helm-switch-to-buffer image-dired-display-image-buffer)
+           (switch-to-buffer image-dired-display-image-buffer)
            (with-current-buffer image-dired-display-image-buffer
              (let ((exif-data (helm-ff-exif-data candidate)))
                (setq default-directory helm-ff-default-directory)

helm-gentoo.el

@@ -102,7 +102,7 @@
   "Gentoo default action that use `helm-gentoo-buffer'."
   (if (member elm helm-cache-world)
       (progn
-        (helm-switch-to-buffer helm-gentoo-buffer)
+        (switch-to-buffer helm-gentoo-buffer)
         (erase-buffer)
         (let ((com-list (append args (list elm))))
           (apply #'call-process command nil t nil
@@ -120,7 +120,7 @@
     (candidate-transformer helm-highlight-local-use)
     (action . (("Description"
                 . (lambda (elm)
-                    (helm-switch-to-buffer helm-gentoo-buffer)
+                    (switch-to-buffer helm-gentoo-buffer)
                     (erase-buffer)
                     (apply #'call-process "euse" nil t nil
                            `("-i"
@@ -138,7 +138,7 @@
                     (helm-gentoo-eshell-action elm "*sudo -p Password: euse -P")))
                ("Show which dep use this flag"
                 . (lambda (elm)
-                    (helm-switch-to-buffer helm-gentoo-buffer)
+                    (switch-to-buffer helm-gentoo-buffer)
                     (erase-buffer)
                     (apply #'call-process "equery" nil t nil
                            `("-C"

helm-grep.el

@@ -1020,7 +1020,7 @@ If a prefix arg is given run grep on all buffers ignoring non--file-buffers."
           (helm-do-grep-1 bufs))
       ;; bufs is empty, thats mean we have only CANDIDATE
       ;; and it is not a buffer-filename, fallback to occur.
-      (helm-switch-to-buffer candidate)
+      (switch-to-buffer candidate)
       (when (get-buffer helm-action-buffer)
         (kill-buffer helm-action-buffer))
       (helm-occur)

helm-ring.el

@@ -176,11 +176,11 @@ replace with STR as yanked string."
     (action . (("Goto line"
                 . (lambda (candidate)
                     (let ((items (split-string candidate ":")))
-                      (helm-switch-to-buffer (cl-second items))
+                      (switch-to-buffer (cl-second items))
                       (helm-goto-line (string-to-number (car items))))))))
     (persistent-action . (lambda (candidate)
                            (let ((items (split-string candidate ":")))
-                             (helm-switch-to-buffer (cl-second items))
+                             (switch-to-buffer (cl-second items))
                              (helm-goto-line (string-to-number (car items)))
                              (helm-highlight-current-line))))
     (persistent-help . "Show this line")))

helm-source.el

@@ -754,10 +754,11 @@ like `re-search-forward', see below documentation of :search slot.")
 
 (defmethod helm--setup-source :before ((source helm-type-buffer))
   (oset source :action (helm-make-actions
-                        "Switch to buffer" 'helm-switch-to-buffer
+                        "Switch to buffer(s)" 'helm-switch-to-buffers
                         (lambda () (and (locate-library "popwin") "Switch to buffer in popup window"))
                         'popwin:popup-buffer
-                        "Switch to buffer other window `C-c o'" 'switch-to-buffer-other-window
+                        "Switch to buffer(s) other window `C-c o'"
+                        'helm-switch-to-buffers-other-window
                         "Switch to buffer other frame `C-c C-o'" 'switch-to-buffer-other-frame
                         (lambda () (and (locate-library "elscreen") "Display buffer in Elscreen"))
                         'helm-find-buffer-on-elscreen

helm-utils.el

@@ -190,11 +190,33 @@ Return nil if DIR is not an existing directory."
             when printer
             collect printer))))
 
-;; Shut up byte compiler in emacs24*.
-(defun helm-switch-to-buffer (buffer-or-name)
-  "Same as `switch-to-buffer' whithout warnings at compile time."
-  (with-no-warnings
-    (switch-to-buffer buffer-or-name)))
+(defun helm-switch-to-buffers (buffer-or-name &optional other-window)
+  "Switch to buffer BUFFER-OR-NAME.
+If more than one buffer marked switch to these buffers in separate windows.
+If OTHER-WINDOW is specified keep current-buffer and switch to others buffers
+in separate windows."
+  (let* ((mkds (helm-marked-candidates))
+         (size (/ (window-height) (length mkds))))
+    (or (<= window-min-height size)
+        (error "Too many buffers to visit simultaneously."))
+    (helm-aif (cdr mkds)
+        (progn
+          (if other-window
+              (switch-to-buffer-other-window (car mkds))
+            (switch-to-buffer (car mkds)))
+          (save-selected-window
+            (cl-loop for b in it
+                  do (progn
+                       (select-window (split-window))
+                       (switch-to-buffer b)))))
+      (if other-window
+          (switch-to-buffer-other-window buffer-or-name)
+        (switch-to-buffer buffer-or-name)))))
+
+(defun helm-switch-to-buffers-other-window (buffer-or-name)
+  "switch to buffer BUFFER-OR-NAME in other window.
+See `helm-switch-to-buffers' for switching to marked buffers."
+  (helm-switch-to-buffers buffer-or-name t))
 
 (cl-defmacro helm-position (item seq &key (test 'eq) all)
   "A simple and faster replacement of CL `position'.