persp-new: return the existing perspective or create a new one

Do not modify an existing perspective, just return it.  If the
perspective doesn't exist, create a new one.

A perspective's scratch buffer is not re-created, and the list
of buffer is preserved as is when the perspective exists.

2 files changed, 9 insertions, 7 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6f5399e..6e1e163 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -64,6 +64,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ### Fixed
 
+- `persp-new`: do not recreate existing perspectives.  This prevents from resetting perspectives to a state where in the perspective there's only the scratch buffer.
 - `persp-reset-windows`: set `switch-to-buffer-preserve-window-point` to `nil` before calling `delete-window`, that up to Emacs 27.2 updates `window-prev-buffers` of all windows, unless the former is turned off.
 - `persp-remove-buffer`: force update the `current-buffer` to the current window's buffer due to `with-selected-window` saving/restoring the `current-buffer` when executing it's BODY.  This properly updates the `current-buffer` to what should be the real current buffer when burying the current buffer.
 - `persp-activate`: force update the `current-buffer` to the current window's buffer due to `make-persp` saving/restoring the `current-buffer` when executing it's BODY.  This properly updates the `current-buffer` to what should be the real current buffer when switching to a new perspective.
diff --git a/perspective.el b/perspective.el
index addc909..2ea7ec1 100644
--- a/perspective.el
+++ b/perspective.el
@@ -551,15 +551,16 @@ window-side creating perspectives."
       (delete-window))))
 
 (defun persp-new (name)
-  "Return a new perspective with name NAME.
+  "Return a perspective named NAME, or create a new one if missing.
 The new perspective will start with only an `initial-major-mode'
 buffer called \"*scratch* (NAME)\"."
-  (make-persp :name name
-    (switch-to-buffer (persp-scratch-buffer name))
-    (funcall initial-major-mode)
-    (when initial-scratch-message
-      (insert initial-scratch-message))
-    (persp-reset-windows)))
+  (or (gethash name (perspectives-hash))
+      (make-persp :name name
+        (switch-to-buffer (persp-scratch-buffer name))
+        (funcall initial-major-mode)
+        (when initial-scratch-message
+          (insert initial-scratch-message))
+        (persp-reset-windows))))
 
 (defun persp-reactivate-buffers (buffers)
   "Raise BUFFERS to the top of the most-recently-selected list.