Ah...thanks!  

- Stephen

> -----Original Message-----
> From: squeak-dev-bounces at lists.squeakfoundation.org 
> [mailto:squeak-dev-bounces at lists.squeakfoundation.org] On 
> Behalf Of Anthony Hannan
> Sent: Thursday, January 30, 2003 12:56 PM
> To: The general-purpose Squeak developers list
> Subject: Re: Dynamic Scoping & Context Based Behavior (was: 
> Dynamic scoping)
> 
> 
> Hi Stephen,
> 
> Your describing perspectives/layers/subject-orientation.  See:
> 
> [Us]  Randall B. Smith and David Ungar. A Simple and Unifying 
> Approach to Subjective Objects. Theory and Practice of Object 
> Systems 2(3):161-178, 1996.  
> http://citeseer.nj.nec.com/smith96simple.html
> 
> [PerspectiveS]  Robert Hirschfeld and Matthias Wagner.  
> PerspectiveS - AspectS with Context.  2002. 
> http://www-ia.tu-ilmenau.de/~hirsch/Projects/Squeak/Perspectiv
> eS/Perspec
> tiveS.html
> 
> Cheers,
> Anthony
> 
> "Stephen Pair" <spair at acm.org> wrote:
> > One of the interesting possibilities that dynamic scoping might 
> > present is that it could be used to set a "behavioral context."  
> > Currently Squeak has only one global "behavioral 
> context"...which is 
> > to say that all objects exhibit the same behavior (roughly 
> speaking) 
> > under all runtime situations in which any given may find itself.
> > 
> > With some modification to the message binding algorithm and the 
> > structure of object memory, I think you could construct a 
> system where 
> > objects could exhibit different behaviors when being utilized in 
> > different runtime "behavioral contexts."
> > 
> > Every object would have some behavior that it exhibits in the global
> > (default) behavioral context.  Additionally, you could add behavior 
> > (and corresponding state) that an object would only exhibit 
> when it is 
> > being utilized from within a specific runtime behavioral context.
> > 
> > A real world analogy is that people, when in different 
> contexts, often 
> > exhibit different behavior.
> > 
> > A good example is a domain object that exhibits GUI 
> rendering behavior 
> > when utilized in the "Morphic" behavioral context.  Upon first 
> > utilization in the Morphic context, the object would adopt the 
> > rendering behavior and state that you had previously 
> defined for all 
> > objects of its class.  This would eliminate the need to have two 
> > separate objects for the model and the view, yet still have 
> all of the 
> > benefits of model-view separation.  Furthermore, if you had 
> different 
> > morphic applications for which different renderings were 
> required for 
> > the same domain object, each application could define its own 
> > behavioral context (which would each inherit from the Morphic 
> > context).  Method lookup would first look for methods in 
> the specific 
> > behavioral context, and then follow an inheritance chain of 
> behavioral 
> > contexts, with the global default behavioral context being 
> the root of 
> > this heirarchy.
> > 
> > - Stephen
> 
>