Re: Signal `quit' in a `font-lock-fontify-region-function'

[Stefan Monnier <monnier@iro.umontreal.ca>]

> So, basically, as I understand, C-g handler in your proposal would
> look like (I know it is in C code, but...), simplified:
>
>     (defun handle-C-g (...)
>       (when registered-many-C-g-callback  ; variable set by e.g.
> font-locking code
>         (setq num-C-g-presses (1+ num-C-g-presses))
>         (when (> num-C-g-presses 3)
>           (funcall registered-many-C-g-callback))))

Not quite, more like:

    (defvar registered-many-C-g-callback (lambda () (signal 'quit nil)))
    (defvar registered-many-C-g nil)

    (defun handle-C-g (...)
      (when registered-many-C-g
        (setq num-C-g-presses (1+ num-C-g-presses))
        (when (> num-C-g-presses 3)
          (funcall registered-many-C-g-callback))))

> and font-locking code would be roughly
>
>     (let ((registered-many-C-g-callback (lambda () (setq font-lock-mode nil))))
>       ; call fontification function, process its result etc.
>       )

More like:

    (let ((registered-many-C-g (cons "font-locking..." registered-many-C-g)))
      ; call fontification function, process its result etc.
      )

But, yes, maybe it would provide a callback to disable font-lock-mode,
or just catch the `quit` signal and disable font-lock-mode.

> `count-C-g-presses' to t.  The idea is to not invoke the "abort"
> callback immediately when the 3rd C-g is pressed, but instead let the
> iteration finish gracefully and _then_ let the higher-level code

Your bounds-extension code could re-bind registered-many-C-g-callback to
do something less drastic than disable font-lock-mode (or exit brutally
from font-lock).


        Stefan