Re: Can we make set_point_both less expensive?

[Stefan Monnier]

>> >> > Another, related, requirement is that we never call
>> >> > pre-redisplay-function when point is in a position that is not
>> >> > supposed to be visible by the user.
>> >> Do you mean invisible text here?
>> > No, I mean positions traversed while "this command" is executed.  The
>> > position shown to the user is the last one of those, but how do we
>> > ensure that pre-redisplay-function is never run for those?
>> Ah, I see what you mean now: the command ensures this by not causing
>> redisplay during its execution.
> Commands don't have full enough control to ensure that, I think.
> Various features and customizations could trigger redisplay behind
> their back.

Of course, but if redisplay is triggered, then the state is
made visible.
So if the state has "a position that is not supposed to be visible by
the user" it's an error for the code to cause redisplay.
The existence and use of pre-redisplay-function doesn't affect this.


        Stefan