Re: Frame ordering

[martin rudalics <rudalics@gmx.at>]

 >> I'd write a simple function to reorder frames, make it callable from
 >> Lisp, and test it from there first.
 >
 > OK, that works.
 > What next?
 > `handle-switch-frame' could be defined in Lisp anyway, calling the current Fhandle_switch_frame primitive.

I don't think so.  IIUC it's purpose is to hide do_switch_frame from
Elisp.

 > That said, why did the same not work in do_switch_frame, and why did my other variant (that I posted) lead to hangs and crashes?
[...]
 > (defun my-handle-switch-frame ( event)
 >   (interactive "e")
 >   (handle-switch-frame event)
 >   (set-latest-frame (selected-frame)))

I can only guess.  do_switch_frame handles an event and when the frame
list is in the state of restructuring and an event occurs, you might end
up with a broken frame list (or a broken window or buffer list given the
fact that do_switch_frame calls `select-window').

In addition, as I recently noticed in the buffer list handling routines,
frame/window/buffer lists are frequently updated via Fdelq and that
function can quit.  I suppose that in all these cases we'd have to use
delq_no_quit (and similar functions) instead to be on the safe side.

Your `my-handle-switch-frame' seems safe because you serialized
`set-latest-frame' with do_switch_frame - so you won't suffer any of the
problems above.  If, however, you were able to interrupt a call to
`set-latest-frame' somehow (maybe by running it in an infinite loop),
you might be able to produce a crash too.

martin