Is this possible?

The documentation for std.container lists "in" as an operator in the container API but only associative arrays actually seem to support it.

struct S
{
	int opIn_r(int key)
	{
		return key*2;
	}
}

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

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?

On 07/02/2014 07:35 AM, 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

I think it is the old syntax, meaning "this is the overload for when an S object is on the right-hand side".

> and lack of documentation?

It appears in the binary operator table:

  http://dlang.org/operatoroverloading.html#Binary

Also see the section 'Inclusion query by opBinaryRight!"in"' here:

  http://ddili.org/ders/d.en/operator_overloading.html

Ali

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);
}

On Wednesday, 2 July 2014 at 15:36:23 UTC, Kozzi11 wrote:
>> 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:

Yep, I think it is D1 legacy approach. opBinary should be more appropriate.

Dicebot:

> Yep, I think it is D1 legacy approach. opBinary should be more appropriate.

I hope the usage of the old operator overloading functions will generate deprecation messages soon.

Bye,
bearophile

On Wed, Jul 02, 2014 at 02:35:54PM +0000, Vlad Levenfeld via Digitalmars-d-learn 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?

Don't use opIn_r, that's a relic from D1. Instead, use this:

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


T

-- 
I think Debian's doing something wrong, `apt-get install pesticide', doesn't seem to remove the bugs on my system! -- Mike Dresser

Ah yes I never noticed that "in" was in the binary op table. In
my defense, searching for "in" usually yields too many results to
be useful. Thanks to everyone for your help!