with-new-context

;; Used to temporarily bind contexts in such a way as to not cause
;; the context garbage collector to run. Used when you don't want to
;; stash away contexts for later use, but simply want to run a piece
;; of code in a new context which will be destroyed when the code finishes.
;; Note that this code COULD use an unwind-protect to be safe but since
;; it will not cause out and out errors we leave it out.

(defmacro with-new-context (sub-context &rest forms)
  `(let ((context (context ,@sub-context)))
     (prog1 ,@forms
       (context-unwinder))))