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

[Randy Hudson <hudsonr@xxxxxxxxxx>]

A "unified" undo story was
proposed for 2.0, which is the reason that this proposal was ignored for
2.0.  Unified undo, where changes in the Navigator somehow mingle
with changes in the Editor, makes no sense.  Similarly, changes made
in 2 different editors should not be mixed together into one undo stack
either (if they are editing completely different resources).

I didn't understand some of hte comments.
 The proposed commands are not text-specific.  Also, AFAIK, flushing
of the command stack does not occur in the Java editor.  It is possible
to undo past the save location all the way to the state when the editor
was opened.

Kai-Uwe Maetzel <kai-uwe_maetzel@xxxxxxx> Sent by: platform-ui-dev-admin@xxxxxxxxxxx 01/20/2003 03:48 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

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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