www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.learn - opApply outside of struct/class scope

reply "Freddy" <Hexagonalstar64 gmail.com> writes:
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
Aug 10 2014
parent reply "Jonathan M Davis" <jmdavisProg gmx.com> writes:
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
Aug 10 2014
parent reply "Era Scarecrow" <rtcvb32 yahoo.com> writes:
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...
Aug 10 2014
parent reply "Jonathan M Davis" <jmdavisProg gmx.com> writes:
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
Aug 10 2014
parent reply "Era Scarecrow" <rtcvb32 yahoo.com> writes:
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 :(
Aug 10 2014
next sibling parent "Era Scarecrow" <rtcvb32 yahoo.com> writes:
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...
Aug 10 2014
prev sibling parent reply "Jonathan M Davis" <jmdavisProg gmx.com> writes:
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
Aug 10 2014
parent "Era Scarecrow" <rtcvb32 yahoo.com> writes:
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.
Aug 10 2014