enum Format

[Richard (Rikki) Andrew Cattermole]

On 11/01/2024 5:31 PM, Nickolay Bukreyev wrote:
> On Thursday, 11 January 2024 at 02:35:00 UTC, Richard (Rikki) Andrew 
> Cattermole wrote:
>> ```d
>> void func(T...)(T args) {
>>     pragma(msg, __traits(getAttributes, args[1])); // format("format")
>> }
>> ```
> 
> Sorry, I don’t understand how this can possibly work. After `func` 
> template is instantiated, its `T` is bound to, e.g., `AliasSeq!(string, 
> int, string)`. `args` is just a local variable of type 
> `AliasSeq!(string, int, string)`. How can `__traits` know what 
> attributes were attached at call site?
> 
> If, on the other hand, attributes do affect the type, then IMHO
> 
> ```d
> func("prefix", @format("format") expr, "suffix");
> ```
> 
> is not much different than
> 
> ```d
> func("prefix", format!"format"(expr), "suffix");
> ```
> 
> I.e., we can do it already.

This has side effects. It affects ``ref`` and ``out``. It also affects 
lifetime analysis.

So we can't do it currently.

But yes, it affects the type, without being in the type system 
explicitly as it is meta data.