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

[Randy Hudson <hudsonr@xxxxxxxxxx>]

Scott--
I'll start off by answering your first
response. I knew about Swing's undo support but have never looked at it
until now. I think the main difference between our approach and the Swing
approach is that Swing is missing the execute portion of the command.  Swing's
UndoableEdit is designed for a text widget, where the change to the "model"
is handled internally by the widget, and the change is simply *documented*
on the undo stack. UndoableEdit does NOT make the change itself.

Our command has a .execute().  It
is intended that the model be changed only by the command.  However,
there are still cases like the ones Swing designed for (for example, continuous
typing).  Editors like Page Designer (an HTML editor) can still achieve
the Swing behavior by making execute() a no-op.

Our CommandStack offers a little more.
 It now contains a mechanism for marking the save point, and then
detecting when the User has undone the stack to the save point, indicating
the Editor is "clean".

Finally, Swing lets you label (and therfore
translate) the command in both directions.  I recommended this at
one point, but none of our translators have identified situations where
this is necessary.

Swing's classes are not a suitable alternative.

Frank--
I don't think this is something unique
to Graphical or EMF-based editors, so I don't think you are arguing that
they should stay in GEF/EMF.
1)Are arguing that they need to be in
Core or some plugin higher-up?
2)What is missing in the proposed API
that cannot be achieved in subclasses?

UI Team--
The TextEditor could benefit from better
undo support.  Lots of cool stuff has been added to AutoIndentStrategies,
but some of these features result in two or more "edits" to the
StyledText widget.  The result is that a single keystroke requires
multiple undos.  For an example, type a Javadoc header '/**' in front
of a method and press ENTER, then undo the change.

-Randy

Scott Stanchfield <scott@xxxxxxxxxxxx> Sent by: platform-ui-dev-admin@xxxxxxxxxxx 01/04/2003 02:18 PM Please respond to platform-ui-dev

To:        platform-ui-dev@xxxxxxxxxxx         cc:        platform-ui-dev-admin@xxxxxxxxxxx         Subject:        RE: [platform-ui-dev] Proposal for CommandStack in JFace

This is the type of thing that would make me suggest
switching both
implementations to the Swing undo framework. It's very similar (from what
I
see so far), and doesn't have any dependency on UI code (despite being
under
javax.swing.undo).

Because it's in the Java core, both EMF and GEF (as well as anything else
that wants undo support) could use it without depending on other plugins.

Thoughts?
-- Scott

==============================================================
Scott Stanchfield    scott@xxxxxxxxxxxx    http://javadude.com

Lead author of "Effective VisualAge for Java, Version 3"
                    
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==============================================================

> -----Original Message-----
> From: platform-ui-dev-admin@xxxxxxxxxxx
> [mailto:platform-ui-dev-admin@xxxxxxxxxxx]On Behalf Of frankb@xxxxxxxxxx
> Sent: Saturday, January 04, 2003 2:12 PM
> To: platform-ui-dev@xxxxxxxxxxx
> Cc: platform-ui-dev@xxxxxxxxxxx; platform-ui-dev-admin@xxxxxxxxxxx
> Subject: Re: [platform-ui-dev] Proposal for CommandStack in JFace
>
>
> This proposal isn't acceptable for EMF. EMF's common commands are
UI
> independent - they can't have a dependency on JFace. The proposed
API is
> also not sufficient.
>
> Frank.
>
>
>
>
>
>
>                    
  Randy
>
>                    
  Hudson/Raleigh/IBM@IBM        To:
> platform-ui-dev@xxxxxxxxxxx
>
>                    
  US                  
         cc:
>
>                    
  Sent by:                
     Subject:
> [platform-ui-dev] Proposal for CommandStack in JFace
>
>                    
  platform-ui-dev-admin@
>
>                    
  eclipse.org
>
>
>
>
>
>                    
  01/03/2003 06:11 PM
>
>                    
  Please respond to
>
>                    
  platform-ui-dev
>
>
>
>
>
>
>
>
>
>
> 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
04 2003
> by Frank Budinsky
>
>
> _______________________________________________
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>


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