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Re: anonymous generic class with reflexive type argument...

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On Sunday, July 12, 2015 at 11:45:53 AM UTC-7, Andreas Leitgeb wrote:
> A while ago, there was a thread about a trick (or pattern) involving 
> a reflexive type argument:
> 
>   abstract class Base<T extends Base<T>> {
>      T doAction() {
>         // do something ...
>         return self(); // for chain-calling.
>      }
>      abstract T self();
>   }
> 
>   class Sub extends Base<Sub> {
>      Sub self() { return this; }
>   }
> 
> So far, that's the pattern (just for the context).
> 
> Now my question is: does there exist also a trick to create an 
> anonymous subclass directly of Base, and if so, how would that
> look like?
> 
>   ... = new Base<???>() {
>      ??? doAction() {
>         // do something more specific
>         return self();
>      }
>      ??? self() { return this; }
>   }
> 
> Of course I could create some non-anonymous and non-generic helper
> class Foo extends Base<Foo>, implement self() returning Foo, and then
> create an anonymous Subclass of Foo, but is there also a direct way?

You'll have to return the immediate supertype, which is the usual practice with anonymous subtypes. 

-- 
Lew

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Thread

anonymous generic class with reflexive type argument... Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2015-07-12 18:44 +0000
  Re: anonymous generic class with reflexive type argument... Lew <lewbloch@gmail.com> - 2015-07-16 17:16 -0700
    Re: anonymous generic class with reflexive type argument... Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2015-07-17 11:40 +0000

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