calendar-in-read-only-buffer

calendar-in-read-only-buffer is a Lisp macro in `calendar.el'.

(calendar-in-read-only-buffer BUFFER &rest BODY)

Switch to BUFFER and execute the forms in BODY.
First creates or erases BUFFER as needed. Leaves BUFFER read-only,
with disabled undo. Leaves point at point-min, displays BUFFER.