struct BigLongStructName
{
	int evenLongerMemberName;
}

struct QN{}

unittest
{
	BigLongStructName bigLongStructName;

	@(bigLongStructName.evenLongerMemberName)
		QN quickName;
	
	__traits(getAttributes, quickName)[0]++;
}

Is it just me or is it weird that this works? Once you pull the UDA out from being a storage class and attempt to alias it, you get the usual "need 'this' for 'evenLongerMemberName' of type 'int'" error messages on use.

Why are UDAs so special? I don't believe there's any other way to achieve this sort of effective renaming.

On Thursday, 9 April 2015 at 09:53:15 UTC, John Colvin wrote:
> struct BigLongStructName
> {
> 	int evenLongerMemberName;
> }
>
> struct QN{}
>
> unittest
> {
> 	BigLongStructName bigLongStructName;
>
> 	@(bigLongStructName.evenLongerMemberName)
> 		QN quickName;
> 	
> 	__traits(getAttributes, quickName)[0]++;
> }
>
> Is it just me or is it weird that this works? Once you pull the UDA out from being a storage class and attempt to alias it, you get the usual "need 'this' for 'evenLongerMemberName' of type 'int'" error messages on use.
>
> Why are UDAs so special? I don't believe there's any other way to achieve this sort of effective renaming.

I think it's an error. When the attribute is a struct, it looks like the member is processed as a static variable. But the equivalent with a class raises an AV:

---
class BigLongStructName
{
	int evenLongerMemberName;
}

struct QN{}

unittest
{
    import std.stdio;

	BigLongStructName bigLongStructName;

	@(bigLongStructName.evenLongerMemberName)
		QN quickName;
	
	__traits(getAttributes, quickName)[0]++;
}
---

which is a totally expected behaviour.

On Thursday, 9 April 2015 at 09:53:15 UTC, John Colvin wrote:
> struct BigLongStructName
> {
> 	int evenLongerMemberName;
> }
>
> struct QN{}
>
> unittest
> {
> 	BigLongStructName bigLongStructName;
>
> 	@(bigLongStructName.evenLongerMemberName)
> 		QN quickName;
> 	
> 	__traits(getAttributes, quickName)[0]++;
> }
>
> Is it just me or is it weird that this works? Once you pull the UDA out from being a storage class and attempt to alias it, you get the usual "need 'this' for 'evenLongerMemberName' of type 'int'" error messages on use.
>
> Why are UDAs so special? I don't believe there's any other way to achieve this sort of effective renaming.

For me it seems to fit into D type system (which is not necessarily is a good idea).

struct S
{
	int i;
}

alias S.i si;

void main(){ /*si++;*/}

Behavior of D depends sometimes on it internals, not on programmers' expectations. Since D has never been stabilized, the boundary between WAT and bugs is partially undefined.