Re: Objects properties - Ada design issues question

[Andy <andy@nospam.com.tj>]

Vladimir Olensky wrote:
> 
> Problem arises ( as I described in previous message)  when we want
> to define common interface to the set of objects ("Black Boxes") derived
> from some root class and we do not know in advance properties  for
> particular derived  object  that should be revealed to the client. In
> addition that properties could be very  different for different derived  
> classes.
> 
> Problem with standard Get  and Set approach is that you need to extend
> interface for each derived type and this breaks our intention to have
> common interface with some limited set of operations  to each "Black Box"
> component.
> 
> So it would be nice to have common interface to different properties
> (that are not known in advance) of different  kind of objects.
> So here use of  ":=" as a standard Get Set operator for any property
> is very useful. We just define in the private part of the implementation
> what this operator does for each particular property without disturbing
> public interface.
> 
But the fact that you would like declare these as properties in a child
class changes the 'common interface'. If a child class has a new
property 
(as can be done in Delphi) or defines additional Get/Set operations as
is
done in Ada 95 - what's the difference. You cannot access these via the 
common interface defined for the root class.

Or am I missing something?

As do your orginal question. One models Delphi properties with Get and
Set operations. Although syntacically different, they provide
essentially
the same operation.

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   Andy Starritt
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