[closer-devel] Dynamic environment capture

[szergling]

Hi Pascal,

I have a quick question, or perhaps a bug report on the new dynamic
environments and their capture. Is 'nested' capture supported?

(defdynamic x nil)
X

(defparameter *y*
  (dlet ((x 1))
    (capture-dynamic-environment)))
*Y*

(with-dynamic-environment (*y*)
  (dynamic x))
1

(defparameter *x*
  (with-dynamic-environment (*y*)
    (capture-dynamic-environment)))
*X*

(with-dynamic-environment (*x*)
  (dynamic x))
NIL

Inspecting *x* shows that its dynamic-winds slot is nil.


I would guess that nested capture is the intended behaviour, from
reading the source. Capture would go through *dynamic-wind-stack*
collecting environments. However, call-with-dynamic-environment
doesn't seem to re-establish *dynamic-wind-stack*. How do I capture
all of *y* in *x* as well? This way, there's a chain of environments
to fallback on.

Thanks in advance for your help.

Theam Yong Chew



Aside:
Should defdynamic be required before we can use dlet?

(dlet ((x 1)) (...))

Should be pretty obvious that x is dynamic. Especially when we access
it via (dynamic x).