Re: it's not just the box dummy - it's just ahouseofcards.-Reply -Reply -Reply

["David Morris" <dmorris@xxxxxxxxxxxxx>]

Rob,

Is a Neural database another way of defining inheritance?  We have database 
based inheritance in some of our applications such as our field definition 
file.  For example a report field can inherit from a database field, from a 
prompt field, etc.  A database field inherits from the file, the prompt field, 
the display attributes.  The key is the parent object, parent type, and object. 
 One major drawback is that a small change at the top can cause big problems at 
the end of the chain.  This is because encapsulation has been violated.  
Because we seldom change the high level definitions it is not a major problem.  
The other option would be to build a fields definition from a set of component 
attributes.  This approach is more flexible but would require more work in the 
application to tie the information together.  It also means it more difficult 
to override an attribute such as field length on a display.

Because we define this inheritance in a linking file that stores direct 
relations between all types of objects we can tie fields to applications, etc.  
Our structure can only return direct relations.  I cannot say where is this 
field used?  Just where the field/parent is used.  This has turned out to be a 
drawback.  It sounds like you may have addressed this issue.  Initially I tried 
to allow this, but the key structure became quite large and cumbersome.  Any 
ideas on how this can be accomplished?

David Morris

<snip>

Taking your example of the Siamese Cat, all those connections may be
there but I do not necessarily need to consider them all together - it
depends on my task (which might considered as another word for
context).  Once you have defined the properties of a "cat" (feline,
mammal etc.,) in the NDB, if you then put in "siamese Cat", it will
automatically inherit the properties of "cat", as will "Persian Cat" if
you put that up later. 


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