[ltk-user] ensure-ltk ?
dherring at tentpost.com
Sun Jan 3 03:42:31 UTC 2010
On Fri, 1 Jan 2010, Daniel Herring wrote:
> What's the proper idiom when writing a function that might start wish or
> might be called inside another with-ltk?
> For example,
> (defun some-window ()
> (ensure-ltk ()
> Where some-window could be called from a REPL or from a tk callback? Is
> there already a way to do this in ltk, or should I define a macro
> something like the following seemingly broken code?
> (defmacro ensure-ltk ((&rest options) &body body)
> (let ((fname (gensym)))
> `(labels ((,fname () , at body))
> (if (wish-stream *wish*)
> (with-ltk ,options (,fname))))))
Here's my current macro. Could it be added to ltk.lisp?
(defmacro ensure-ltk ((&rest options &key (debug 2)
"Wrap BODY in with-ltk unless a connection already exists."
(declare (ignore debug))
(let ((fname (gensym)))
`(flet ((,fname () , at body))
(if (wish-stream *wish*)
(with-ltk ,options (,fname))))))
It turns out that both ensure-ltk macros work. However care must be
exercised; my first use triggered Tk bug #219967. My distilled Ltk sample
;; This can freeze a graphical window manager.
;; To run on linux and recover:
;; - log into a text console (e.g. Ctrl-Alt-F2)
;; - switch graphical (Ctrl-F7) and run the bomb
;; - switch back to text and `killall wish`
;; - watch `top` until things calm down
(defun bomb ()
(pack (make-instance 'treeview))
;; commenting out the sleep might save your window manager
(sleep 1) ; just to let the treeview appear
(grid (make-instance 'label :master nil) 0 0)))
Even without this Tk bug, its probably a good idea to always pass a proper
:master to other functions which create widgets...
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