Proposal: __not(keyword)

[Neia Neutuladh]

On Friday, 14 September 2018 at 18:13:49 UTC, Eugene Wissner 
wrote:
> Makes the code unreadable. You have to count all attributes in 
> the file, then negate them. Nobody should write like this and 
> therefore it is good, that there isn't something like __not.
>
> For @nogc, pure and so forth there were imho a better proposal 
> with a boolean value:
> @gc(true), @gc(false), pure(true), pure(false) etc. It is also 
> consistent with the existing UDA syntax.

The two proposals are extremely similar in effect. Under Adam D 
Ruppe's proposal, I could write:

__not(@nogc) void foo() {}

Here, @nogc wasn't set, so I didn't need to specify any 
attributes. If @nogc: had been specified a thousand times just 
above this function, __not(@nogc) would still make `foo` be 
not- at nogc.

Identically, under your proposal, I could write:

@gc(true) void foo() {}

If this is the entire file, the annotation has no effect. If 
@gc(false) had been specified a thousand times just above this 
function, the annotation would still make `foo` be not- at nogc.

There's no counting of attributes to negate. You just negate 
everything that doesn't apply to this function.