While the macro version doesn't permit this, if it were built-in syntax (as in C#) we can write something like:
using (auto res1 = acquire1(); free(res1))
using (auto res2 = acquire2(); free(res2))
using (auto res3 = acquire3(); free(res3))
{
// use resources here
}
// free(res3); free(res2); free(res1); called in that order.
The argument for this approach is it is structural. `defer` statements are not structural control flow: They're `goto` or `comefrom` in disguise.---
Even if we didn't want to introduce new scope, we could have something like F#'s `use`[1], which makes the resource available until the end of the scope it was introduced.
use auto res1 = acquire1() defer { free(res1); };
use auto res2 = acquire2() defer { free(res2); };
use auto res3 = acquire3() defer { free(res3); };
// use resources here
In either case (using or use-defer), the acquisition and release are coupled together in the code. With `defer` statements they're scattered as separate statements. The main argument for `defer` is to keep the acquisition and release of resources together in code, but defer statements fail at doing that.[1]:https://learn.microsoft.com/en-us/dotnet/fsharp/language-ref...