On Mon, Sep 22, 2008 at 6:25 PM, Waldemar Horwat <[EMAIL PROTECTED]> wrote: > Graydon Hoare wrote: >> Quoting Liskov[1]: >> >> "What is wanted here is something like the following substitution >> property: If for each object o1 of type S there is an object o2 of >> type T such that for all programs P defined in terms of T, the >> behavior of P is unchanged when o1 is substituted for o2, then S >> is a subtype of T." >> >> Think it over. Imagine what you'd have to delete from any language you >> use, for its "subtype" relation to conform to that definition. > > What? For example, what would you have to delete from Java, ignoring the > parts where a program can examine itself like reflection?
I don't know that I would phrase it in terms of deleting functionality from the language, but it's pretty clear that Java's notion of subtyping is not Liskov's. Here's a simple illustration: http://doodleproject.sourceforge.net/articles/2000/liskovSubstitutionPrinciple.html _______________________________________________ Es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
