RE: Defininng and using an object as a Swarm and a SwarmObject at the same time.

[Joseph E. Villa]

Alex,

Thanks for the correction/commentary! What is the appropriate way to
refer to the following (the part where two interfaces subclass/inherit
from two superclasses [SwarmObject & GUISwarm] within a single class
[simpleExperBug])?

Joseph Villa

================================================================

// ExperSwarm.h                                 simpleExperBug

// The ExperSwarm is a swarm that manages multiple invocations of a
// model. 

#import "ModelSwarm.h"
#import <simtoolsgui/GUISwarm.h>
#import <objectbase/SwarmObject.h>
#import <objectbase.h>
#import <analysis.h>

// First, the interface for the ParameterManager

@interface ParameterManager: SwarmObject
...
@end


// Now, the Experiment Swarm Interface

@interface ExperSwarm: GUISwarm
...
@end

================================================================

> -----Original Message-----
> From: Alex Lancaster [mailto:address@hidden
> Sent: Sunday, March 21, 1999 10:08 PM
> To: address@hidden
> Subject: Re: Defininng and using an object as a Swarm and a 
> SwarmObject
> at the same time.
> 
> 
> >>>>> "JV" == Joseph E Villa <address@hidden> writes:
> 
> JV> It seems what you've proposed is multiple inheritance. There's
> JV> certainly a lot of discussion in OO design about multiple
> JV> inheritance, and some would have you believe it is inheritantly
> JV> (*g*) problematic from a pure design perspective. (I tend to stay
> JV> away from multile inheritance, but I suspect this is one of those
> JV> religious fervor topics.)
> 
> JV> You may be able to achieve multiple inheritence by including the
> JV> SwarmObject.h and Swarm.h files in your Population
> JV> files. (Cruising through some of the root Swarm classes, I think I
> JV> came across this.)
> 
> Unfortunately this won't work (we don't use multiple inheritance
> anywhere in the Swarm kernel).  Objective C (and therefore Swarm)
> doesn't support multiple-inheritance directly (C++ does, but Java
> doesn't).  But there are several ways to achieve a similar effect.
> You can use Objective C protocols (to construct classes that conform
> to a given interface, but that doesn't necessarily allow you access to
> the *implementation*, like true multiple inheritance does).
> 
> Here's an online reference from the NeXT Objective C manual (now
> hosted on the Apple website):
> 
>   
> http://developer.apple.com/techpubs/macosxserver/System/Docume
> ntation/Developer/YellowBox/TasksAndConcepts/ObjectiveC/moreob
> jc.htm#787
> 
> The other approach is to use forwarding to mimic multiple inheritance,
> the NeXT book on Objective C discusses this approach in more detail:
> 
>   
> http://developer.apple.com/techpubs/macosxserver/System/Docume
> ntation/Developer/YellowBox/TasksAndConcepts/ObjectiveC/runtim
> e.htm#1005
> 
> The top level for this online Objective C book is at:
> 
>   
> http://developer.apple.com/techpubs/macosxserver/ObjectiveC/index.html
> 
> 
>  -- Alex
> 
> -- 
>   Alex Lancaster           |  e-mail: address@hidden
>   Swarm Program            |     web: http://www.santafe.edu/~alex
>   Santa Fe Institute       |     tel: +1-(505) 984-8800
> -------------------------------------------------------------------
> 
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                  ==================================
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