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c#async-awaitidisposable

Discard async result when result implements IDisposable

using var notNeeded = await foo();

foo returns an object which implements IDisposable but that object can be discarded immediately. What is the idomatic way to write this line?

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

Are there any more elegant ways?

Solution

  • My preference for disposing immediately a non-needed IDisposable object:

    (await foo()).Dispose();

    ...and in case it's IAsyncDisposable:

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