SV: [Nautilus-list] Status...

["Blad, John Erling" <john erling blad aftenposten no>]

Did this once as a linked list of objects that holds undo-redo pairs. If an action
was marked as undoable then the list was chopped off. An action object held a
callback, a name and a boolean if this was possible (tested against a global state).

No branches on the list because the user quicly forget previous actions. Usually
the user shuffeled back and forth until he found the right action (ie "undo" until
you get the right spot then "redo" from the next).

What's necessary are "Undo" and "Redo" that are submenus instead of the usual buttons.

John

-----Opprinnelig melding-----
Fra: Calum Benson [mailto:calum benson sun com]
Sendt: 7. november 2000 17:51
Til: nautilus-list lists eazel com
Emne: Re: [Nautilus-list] Status...


John Sullivan wrote:

> > Yes, come to think of it, I'd never actually tried to Undo a permanent
> > delete on Windows, for example... and you can't, which sort of makes
> > sense.  The trashcan *is* the Undo feature for deletes... which you
> > could argue is sort of confusing in itself-- why should Undo-ing a
> > delete be any different from undoing anything else?  But we can debate
> > that one some other time :o)
> 
> There is a very good reason for this, actually. Undo is linear -- that is,
> you can only undo actions in the reverse order that they were performed.

Well, that's the convention these days, certainly... but it's not
necessarily always very useful.  It's admittedly hard to do it any other
way *if* you've subsequently changed the object to which a particular
action in the undo list applies-- but quite often you haven't.

For example, in a word processing app, if I format a paragraph a
particular way, go away and edit some other part of the document, then
decide I want that paragraph back the way it was, there's no reason on
earth why I should be forced to undo everything I've done since... and
there's many a time I've cursed an application for forcing me to do just
that!

Wouldn't it be wonderful if an action in the undo list remained
independently reversible throughout its "undoable" lifespan (i.e. in the
simplest case, until you subsequently changed the object to which it
applied)?  Sure it's a non-trivial problem, but that's what we're here
for  :o)

Cheeri,
Calum.

-- 
CALUM BENSON, Usability Engineer       Sun Microsystems Ireland
mailto:calum benson ireland sun com    Desktop Engineering Group
http://www.sun.ie                      +353 1 819 9771

Any opinions are personal and not necessarily those of Sun Microsystems


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