Re: indirect-buffers and text-properties

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

>>> Really? I've started using them because they enable me to have the point
>>> in two places at once; for example, in the pre-amble and the body of a
>> [...]
>>> visible window). Indirect buffers seem to be a nice solution for this.
>> That would be using a definition of "nice" very different from the one
>> I'm familiar with ;-)
>> BTW, you might like to M-x report-emacs-bug and request exactly this
>> feature for "preserving window-specific point".  It can probably be
>> implemented in a *much* lighter way than by using indirect-buffers.
> I would, but I am not sure what the correct behavour is.
> Consider:
>   Window 1 (point at beg)
>   ----
>   Window 2 (point at end)
> C-x 1
>   Window 1 (point at beg)

> C-x 2
>   Window 1 (point at beg)
>   ----
>   Window 2 (point at beg)

> If one of the two windows is indirect, at least point is preserved
> somewhere, so I can get back to it.

We could stash the window-point to some buffer-local variable
buffer-other-points when the window is removed, and when the buffer is
displayed in a new window, we could check if buffer-other-points holds
other locations and reuse them.  And/or provide a new command to cycle
through those buffer-other-points.  And/or use the mark-ring instead of
buffer-other-points and just let the user use mark-ring navigation to
return to the previous position.

> Okay, I have to accept your word on this, but I can't see another
> solution in my head. The best I have come up with is to hook into the
> change-functions, and link two (otherwise independent buffers) together
> so that the text in both is identical.  AFAICT this is tractable, at
> least if I only edit one of them.

I tend to this the "multiple major-mode in a single buffer" option would
work better.

But in any case, there is no simple solution like "indirect-buffer".

Each of the major modes that participate in a mixed-mode buffer needs to
be written in a way that is aware of the fact that there can be other
modes on other parts of the buffer.


        Stefan