automatic subtyping/intensions

William Tanksley wtanksle@UCSD.EDU
Tue, 9 Feb 1999 10:08:15 -0800 (PST)

On 9 Feb 1999, Laurent Martelli wrote:

>>>>>> "Tril" == Tril  <> writes:

>    >> 1 - B. Liskov and J. Wing: "A Behavioral Notion of Subtyping",
>    >> ACM Transactions on Programming Languages and Systems, Number
>    >> 16(6), pp. 1811-1841, ACM Press, 1994.

>    Tril> Could you summarize the content of the article?  What is
>    Tril> meant by a "behavioral notion?"

>It means that a type A is a subtype of B if objects of type A behave
>exactly the same way as objects of type B. This is the LSP (Liskov
>Substitution Principle) : if a function says it wants an argument of
>type B, you can give it an object of type A, and it wont see the
>difference. This definition does not rely on the name of understood
>messages but rather on their semantic.

Does this article actually tell how to achieve this, or is it just another
one saying how *nice* it would be if we could ...?