http://blog.originate.com/blog/2014/02/27/types-inside-types-in-scala/
On Wed, Aug 31, 2016 at 2:19 AM, Sean Owen <so...@cloudera.com> wrote:
> Weird, I recompiled Spark with a similar change to Model and it seemed
> to work but maybe I missed a step in there.
>
> On Wed, Aug 31, 2016 at 6:33 AM, Mohit Jaggi <mohitja...@gmail.com> wrote:
>> I think I figured it out. There is indeed "something deeper in Scala” :-)
>>
>> abstract class A {
>> def a: this.type
>> }
>>
>> class AA(i: Int) extends A {
>> def a = this
>> }
>>
>> the above works ok. But if you return anything other than “this”, you will
>> get a compile error.
>>
>> abstract class A {
>> def a: this.type
>> }
>>
>> class AA(i: Int) extends A {
>> def a = new AA(1)
>> }
>>
>> Error:(33, 11) type mismatch;
>> found : com.dataorchard.datagears.AA
>> required: AA.this.type
>> def a = new AA(1)
>> ^
>>
>> So you have to do:
>>
>> abstract class A[T <: A[T]] {
>> def a: T
>> }
>>
>> class AA(i: Int) extends A[AA] {
>> def a = new AA(1)
>> }
>>
>>
>>
>> Mohit Jaggi
>> Founder,
>> Data Orchard LLC
>> www.dataorchardllc.com
>>
>>
>
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