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From tao zhan <zhanta...@gmail.com>
Subject Re: Question on Spark code
Date Mon, 24 Jul 2017 03:47:42 GMT
Thank you for replying.
But I do not get it completely, why does the "this.type“” necessary?
why could not it be like:

def setStepSize(step: Double): Unit = {
    require(step > 0,
      s"Initial step size must be positive but got ${step}")
    this.stepSize = step
}

On Mon, Jul 24, 2017 at 11:29 AM, M. Muvaffak ONUŞ <onus.muvaffak@gmail.com>
wrote:

> Doesn't it mean the return type will be type of "this" class. So, it
> doesn't have to be this instance of the class but it has to be type of this
> instance of the class. When you have a stack of inheritance and call that
> function, it will return the same type with the level that you called it.
>
> On Sun, Jul 23, 2017 at 8:20 PM Reynold Xin <rxin@databricks.com> wrote:
>
>> It means the same object ("this") is returned.
>>
>> On Sun, Jul 23, 2017 at 8:16 PM, tao zhan <zhantao92@gmail.com> wrote:
>>
>>> Hello,
>>>
>>> I am new to scala and spark.
>>> What does the "this.type" in set function for?
>>>
>>>
>>> ​
>>> https://github.com/apache/spark/blob/481f0792944d9a77f0fe8b5e2596da
>>> 1d600b9d0a/mllib/src/main/scala/org/apache/spark/mllib/
>>> optimization/GradientDescent.scala#L48
>>>
>>> Thanks!
>>>
>>> Zhan
>>>
>>
>>

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