On Wednesday 08 August 2001 07:07 am, Josh wrote:

> > In
> > effect, it raises the question of whether a tool "should be applied" to
> > an object or whether an object "should provide a service" if stimulated
> > with a certain tool. In my understanding, the latter is almost always the
> > better way to go although I do understand that changing existing (e.g.,
> > predefined) classes is not always a good thing to do.
>
> Could you point me at some literature on the topic?  The only thing I've
> read wrt tools in object-oriented GUI frameworks was a paper on InterViews.

You should look at HotDraw as well
 http://st-www.cs.uiuc.edu/users/brant/HotDraw/HotDraw.html

In HotDraw, changing tools switches the state machine used to respond to user 
interaction.

There is an interesting paper about creating tools by composition at
ftp://st.cs.uiuc.edu/pub/papers/HotDraw/HotDrawTools.ps.Z

HotDraw has several kinds of tools that apply to different things:
* CreationTool makes new objects
* DrawingActionTool does something to the whole drawing
* FigureActionTool does something to the next selected (clicked) object.

Each of the kinds of tools also supplies an icon and a cursor (as I recall).

-- 
Ned Konz
currently: Stanwood, WA
email:     ned at bike-nomad.com
homepage:  http://bike-nomad.com