c# - 当结果实现 IDisposable 时丢弃异步结果

Question

using var notNeeded = await foo();

foo 返回一个实现 IDisposable 的对象，但该对象可以立即丢弃。写这行代码的方式是什么？

using var notNeeded = await foo(); // (1) possible lint error: unused variable
using var _ = await foo(); // (2) looks clean but lives until the end of the function (which is rarely an issue)
using _ = await foo(); // (3) not legal
using (await foo()); // (4) possible lint error: possible mistaken empty statement
using (await foo()) {} // (5) looks like a mistake but actually does call Dispose() immediately

还有更优雅的方式吗？

Answer 1

我倾向于立即处置不需要的 IDisposable 对象:

(await foo()).Dispose();

...如果它是 IAsyncDisposable:

await (await foo()).DisposeAsync();