Re: Mixing OO and DB

Bob Badour wrote:

> S Perryman wrote:

>> Specifically : what "principle" is actually in effect here ??

>> That if some type T2 happens to be substitutable for T1 for one
>> particular context, that T2 should be a Liskov/Wing subtype of T1 ??

>> Hardly "value-added" (wrt to the Liskov/Wing definitions) is it.

> Actually, the principle provides a method to evaluate type systems just > as normalization provides a method to evaluate logical designs.

FORALL System S, FORALL Type T1,T2 IN S, the Liskov/Wing subtype definition certainly provides the means to evaluate the degree of substitutability possible for any given T1/T2.

I assume the above is what you meant by "type systems" (otherwise the analogy with normalisation is not a good one) . If I am mistaken, please feel free to correct me.

Regards,
Steven Perryman Received on Fri Feb 22 2008 - 03:09:56 CST