Re: [platform-ui-dev] Proposal for CommandStack in JFace

[Kai-Uwe Maetzel <kai-uwe_maetzel@xxxxxxx>]

Nick already pointed out the problem. The undo story should not be relying 
on text but be available for all kind of actions. This includes not just 
editors but all actions that can be performed from the navigator, packages 
explorer, etc.

Having the common separation between core and ui, providing undo support 
from the ui layer up is probably not sufficient.

Having a unified undo story the problem of completeness remains. If only 
selected operations/actions can be reverted, flushing the undo stack is 
challenging as it requires a component to judge each delta according to its 
potential to invalidate the undo stack based on partial knowledge. If the 
undo stack belongs to only one component this is simpler. If all 
operations/actions can be reverted it is only a question of work flow 
design when to flush the undo stack.

Kai


At 02:31 PM 1/20/2003 -0500, you wrote:
> I'll let the Text team comment on whether they think that would make
> sense.
>
> However, there may well be graphical editors (i.e. those based on GEF)
> that don't even need the basic text support.
>
> Nick
>
>
>
>
>
> David M Williams/Raleigh/IBM@IBMUS
> Sent by: platform-ui-dev-admin@xxxxxxxxxxx
> 01/20/03 01:23 PM
> Please respond to platform-ui-dev
>
>
>         To:     platform-ui-dev@xxxxxxxxxxx, platform-text-dev@xxxxxxxxxxx
>         cc:
>         Subject:        Re: [platform-ui-dev] Proposal for CommandStack 
> in JFace
>
>
>
>
>
>
>
> Wouldn't the (new) org.eclipse.text plugin be a good location for this
> functionality? Even though the packages still have 'jface' in the name,
> they are actually UI independent and could be a pre-req of plugins that
> didn't want to pull in UI related code. Right?
>
> David
>
>
>
>
>
>                       Nick_Edgar@xxxxxxxxxx
>                       Sent by:                      To:
> platform-ui-dev@xxxxxxxxxxx
>                       platform-ui-dev-admin@        cc:
>                       eclipse.org                   Subject:  Re:
> [platform-ui-dev] Proposal for CommandStack in JFace
>
>
>                       01/13/2003 11:47 AM
>                       Please respond to
>                       platform-ui-dev
>
>
>
>
>
>
> Randy,
>
> I am sympathetic to having a shared Undo/Redo facility, whether at the
> Workbench level, JFace level, or below (we don't currently have a good
> place to put this below JFace though).
> It would also be beneficial to have some support at the Workbench level,
> so that coupling of command stacks with the Undo and Redo global actions
> could be simplified.
>
> I've asked the Platform-Text and JDT-UI component owners to look at your
> Command framework to see whether it would meet their needs, since they are
> currently the main implementors of interesting undo/redo commands in the
> current SDK.
>
> Nick
>
>
>
>
>
> Randy Hudson/Raleigh/IBM@IBMUS
> Sent by: platform-ui-dev-admin@xxxxxxxxxxx
> 01/03/03 06:11 PM
> Please respond to platform-ui-dev
>
>
>         To:     platform-ui-dev@xxxxxxxxxxx
>         cc:
>         Subject:        [platform-ui-dev] Proposal for CommandStack in
> JFace
>
>
>
>
> GEF provides a Command and CommandStack implementation. This should be
> moved into JFace (which was proposed _too_ late during the 2.0
> developement cycle).
>
> Other technologies such as EMF [Edit] also require their own Command and
> CommandStack. We have both invented the wheel. When plugins combine GEF
> and EMF, it becomes difficult to deal with multiple definitions of the
> same concept/classes.
>
> Attached is a proposal for a Command and CommandStack implementation.
>  Moving them into JFace will simplify future WSAD releases as well as the
> work of others who are combining the "Tools" plugins mentioned above.
>
> We are considering one more feature for the CommandStack (the ability to
> append to an executing command), but the code itself it pretty simple and
> stable ;-)
>
> -Randy
>
>
>
>
> #### JFaceCommands.jar has been removed from this note on January 13, 2003
> by Nick Edgar
>
>
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