Use of super in type parameters (original) (raw)

Dan Smith daniel.smith at oracle.com
Thu Apr 18 09:33:08 PDT 2013

On Apr 17, 2013, at 6:11 PM, Zhong Yu <zhong.j.yu at gmail.com> wrote:

On Wed, Apr 17, 2013 at 4:53 PM, Martin Buchholz <martinrb at google.com> wrote:

With the coming of lambda, it is more likely that people will be creating APIs with "not quite correct" generic types, as we are doing in I believe that we can tweak generic signatures in APIs without breaking calling codes.

It's one thing to make a change that won't break callers. It's another to make a change that won't break implementers.

foo(List, List) but we declare it today as, regrettably, foo(List<? super T>, List<? super T>)

Unfortunately (without some sort of language change...), neither one of these signatures can be used to override the other. So if somebody extends my class and overrides my signature, when I change it to the other one later, their code will break.

—Dan

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