Negation of attributes (DIP 79)

[Jonathan M Davis via Digitalmars-d]

On Thursday, 4 June 2015 at 08:46:50 UTC, Daniel Kozák wrote:
> If I will go with !attr, there will be no way to add 
> compile-time
> expressions to it. But if we start with attr(true) or 
> attr(false), it
> can be easily extended to support compile-time expressions in 
> future.

I can see that. But I also see no point in designing it for 
possible extensibility later rather than just outright doing it 
now. At most, I can see implementing it with just attr(true) and 
attr(false) initially in order to get it in with the idea that we 
_will_ add full support for arbitrary, compile-time boolean 
expressions later, and not that we _might_ such support later. 
But my guess is that there really isn't much difference in the 
amount of work required to allow arbitrary compile-time boolean 
expressions, because we do that sort of thing in plenty of places 
already, so it's not like that would have to be done from 
scratch. I'm not a compiler dev though, and they'd have a better 
idea about that.

Regardless, it's quite clear that we have cases in generic code 
where attr(boolean expression) will be useful, so we should just 
go for it.

- Jonathan M Davis