[slime-devel] Re: SBCL restart-frame

jcm@FreeBSD-uk.eu.org wrote:

On Sat, Jan 14, 2006 at 11:11:18PM +0100, Mészáros Levente wrote: : Hi, : : I am relatively new to SBCL and SLIME, so maybe I'm wrong about this. I : did not find restart-frame support for SBCL, so I did this patch and it : seems to work for me.

Is it really this simple?

Not quite. The restarted function will be run in the wrong dynamic environment. For example:

(declaim (optimize (debug 2)))

(defvar *a* 0)

(defun foo (a) (let ((*a* (1+ *a*))) (/ 2 a)))

(defun bar () (print *a*) (foo 0))

When you call BAR, it'll print 0 and then call FOO, which will signal an error. If we now restart BAR, the dynamic binding for *A* that FOO established will still be visibile, and it'll print 1 instead.