[climacs-devel] a paragraph on persistent buffers
Aleksandar Bakic
a_bakic at yahoo.com
Tue May 24 17:54:33 UTC 2005
> > > An undo record of a regular buffer only keeps an editing
> > > operation, I think.
> >
> > I can´t access the code at the moment, but I guess a regular undo record
> also
> > keeps a pointer to the buffer (as opposed to the contents of it (a tree)
> kept
> > by a persistent undo record), so the difference is an edit operation (at
> > least).
>
> Not sure what you mean, but if memory serves, an undo record contains
> buffer offsets as opposed to (say) marks, since we rely on undo
> operations to be applied in the reverse order compared to ordinary
> operations.
Sorry, I am forgetting the terminology. I meant the same by the "editing
operation": offsets plus the kind of operation and perhaps a text operand. The
operation gets reversed once it is undone so that it can be redone. No such
thing in a persistent buffer's undo record. (Also, just to repeat: with both
kinds of buffers, markers are generally invalidated by undo/redo, even though
they remain valid for some undo/redo operations with standard buffers.)
Alex
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