overloading InExpression

[Kozzi11 via Digitalmars-d-learn]

On Wednesday, 2 July 2014 at 14:35:55 UTC, Vlad Levenfeld wrote:
> On Wednesday, 2 July 2014 at 14:14:57 UTC, Dicebot wrote:
>> struct S
>> {
>> 	int opIn_r(int key)
>> 	{
>> 		return key*2;
>> 	}
>> }
>>
>> void main()
>> {
>> 	assert((42 in S.init) == 84);
>> }
>
> Thanks! I wonder, why the _r and lack of documentation?

Maybe something from old days? But in current <a
href="http://dlang.org/operatoroverloading.html#Binary"
target="_blank">doc</a> there is a opBinary:

struct S
{
      int opBinaryRight(string op : "in")(int key)
      {
          return key*2;
      }
}

void main()
{
      assert((42 in S.init) == 84);
}