2014-09-03

Resolving let-method (2)

I've got sharp comment on previous article. Apart from the comment, I've found sort of critical issue on thread local storage solution. That is evaluating library form in eval won't add method to generic function. Well library form is not allowed to evaluate with eval on both R6RS and R7RS however Sagittarius allows it. (And I might have already written such code ...)

So forget about thread local storage. For now add-method checks current environment whether or not it's a child environment which is created by either environment procedure or a thread. The name child environment may confuse you but I just don't have any good name for this, so bare with it :) If add-method is called in child environment then it adds method to only in that context. If not, then adds globally.

Difference? Well sort of the same but it has now a way to affect changes globally. In the remote REPL situation discussed in previous article comment, it can be done with with-library macro. Other changes are only in the child context.

;; in remote REPL and we want to apply a patch
(import (sagittarius control))

(with-library (foo)
  ;; fix it
  (define-method bar ...))
This is just a fix before I forget, so it's time to read the paper.

No comments:

Post a Comment