I'm trying to implement a opApply outside of struct scope
----
struct A{
	int[] arr;
}
int opApply(ref A a,int delegate(ref int) dg){
	return 0;
}
void main(){
	A a;
	foreach(i;a){//i just want it to compile
		
	}
}
----
when i try compiling, the compiler errors:
  test.d(9): Error: invalid foreach aggregate a
Is there any why i can put a opApply outside of a struct scope,if
so is there any why that the opApply can be templated

On Sunday, 10 August 2014 at 18:45:00 UTC, Freddy wrote:
> Is there any why i can put a opApply outside of a struct scope

No overloaded operators in D can be put outside of a struct or class. They have to be member functions.

- Jonathan M Davis

On Sunday, 10 August 2014 at 18:58:50 UTC, Jonathan M Davis wrote:
> No overloaded operators in D can be put outside of a struct or class. They have to be member functions.

 If I remember right, opApply was somewhat broken and only worked correctly in a few cases. But that was 18 months ago, a lot could have happened...

On Sunday, 10 August 2014 at 19:01:18 UTC, Era Scarecrow wrote:
> On Sunday, 10 August 2014 at 18:58:50 UTC, Jonathan M Davis wrote:
>> No overloaded operators in D can be put outside of a struct or class. They have to be member functions.
>
>  If I remember right, opApply was somewhat broken and only worked correctly in a few cases. But that was 18 months ago, a lot could have happened...

I'm not aware of opApply being broken, but I never use it, since in most cases where you might use opApply, you can use ranges, and they're far more flexible. But regardless, it's not legal to declare an overloaded operator outside of the type that it's for, so whether you're talking about opApply, opBinary, opAssign, or any other overloaded operator, declaring it as a free function like the OP is trying to do isn't going to work.

- Jonathan M Davis

On Sunday, 10 August 2014 at 21:57:29 UTC, Jonathan M Davis wrote:
> I'm not aware of opApply being broken, but I never use it,

 I remember very specifically it was brought up, that opApply was not working correctly and you could only use it with a very specific cases because... the implementation was incomplete?

 I think the discussion was partially on removing opApply from BitArray and going for a range or array approach instead because the problem would go away, but a lot of this is fuzzy and from memory. I have so much to catch up on :(

On Sunday, 10 August 2014 at 22:03:28 UTC, Era Scarecrow wrote:
>  I remember very specifically it was brought up,


On Wed, Jul 09, 2014 at 03:16:37PM -0700, H. S. Teoh via Digitalmars-d wrote:
> Judging from this, a big missing piece of the current implementation is the actual enforcement of 'scope'.

 Or it was that scope was originally suppose to be part of the opApply and that's what i'm thinking about.... stuff i find in other threads...

On Sunday, 10 August 2014 at 22:03:28 UTC, Era Scarecrow wrote:
> On Sunday, 10 August 2014 at 21:57:29 UTC, Jonathan M Davis wrote:
>> I'm not aware of opApply being broken, but I never use it,
>
>  I remember very specifically it was brought up, that opApply was not working correctly and you could only use it with a very specific cases because... the implementation was incomplete?
>
>  I think the discussion was partially on removing opApply from BitArray and going for a range or array approach instead because the problem would go away, but a lot of this is fuzzy and from memory. I have so much to catch up on :(

IIRC, opApply doesn't play well with various attributes, but I don't remember the details. That's the only issue with opApply that I'm aware of. It looks like you'll have to go digging into those other threads if you want to know what was supposed to be wrong with it.

- Jonathan M Davis

On Monday, 11 August 2014 at 02:03:15 UTC, Jonathan M Davis wrote:
> IIRC, opApply doesn't play well with various attributes, but I don't remember the details. That's the only issue with opApply that I'm aware of. It looks like you'll have to go digging into those other threads if you want to know what was supposed to be wrong with it.

 Pretty sure it was the scope keyword rather than opApply. Maybe that it didn't play well with out or inout or some combination, or const or something...

 http://forum.dlang.org/thread/mailman.1363.1339173331.24740.digitalmars-d-learn@puremagic.com

 Oh well. Not important enough to keep talking about.