Re: indirect-buffers and text-properties

[phillip.lord@newcastle.ac.uk (Phillip Lord)]

Stefan Monnier <monnier@iro.umontreal.ca> writes:
>> 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.


>
>> Even as it stands, having the same content in two different modes seems
>> very powerful;
>
> It is very powerful, but as you've seen indirect-buffers only work to
> some extent for that purpose and the problems you bump into are largely
> unsolvable.  So it's not going in the right direction.
>
> I think they really fit perfectly the definition of attractive-nuisance.

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. 

So, I'd have something like `make-indirect-view' which would open an
indirect buffer, in a new window, read-only, but in a different mode.
Then `swap-modes' which would take the major mode of the editable
buffer, and the uneditable buffer and swap the two. Finally, somelike
`sync-indirect-view' would display make the two display the same parts.

Seems like a reasonable amount of work to do, but could be usuable.

Phil