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Write the options out without blocking the caller.

public Task SaveAsync(Stream destination, CancellationToken cancellationToken = default)

Parameters — destination is a writable stream, left open. cancellationToken cancels the write.

Returns — Task, completing when the options have been written.

Exceptions — ArgumentException, the JSON writer's own, as 0.7.0 raised it, when the token pattern or a stop word is beyond what the writer can write. InvalidDataException when MinDf or MaxDf is not finite, which the constructor does not refuse. Both are refused before anything is written (#1618, #1622, #1646). NotSupportedException, the stream's own, when it cannot be written to, raised by the write once the artifact is composed, as 0.7.0 raised it. IndexOutOfRangeException, the writer's own as well, for a string whose escaped form passes its buffer, as 0.7.0 raised it. ArgumentNullException for a null stream. OperationCanceledException when cancelled.

Example — the round trip, asynchronously.

using Lodestar.Text.Vectorization;

static async Task<int> RoundTripAsync()
{
    var hv = new HashingVectorizer(new HashingVectorizerOptions { NumFeatures = 16 });

    using var buffer = new MemoryStream();
    await hv.SaveAsync(buffer);
    buffer.Position = 0;

    HashingVectorizer restored = await HashingVectorizer.LoadAsync(buffer);
    return restored.NumFeatures;
}

int columns = RoundTripAsync().GetAwaiter().GetResult();  // => 16

The GetAwaiter().GetResult() is only what lets a synchronous example drive an async one; in async code the call is simply await.

Remarks — what is written is a handful of settings, so the asynchronous overload buys little here beyond keeping this type interchangeable with the other two. As with them, there is no string path overload: opening the file with useAsync: true belongs to the caller.

Applies to — net10.0, netstandard2.0.

See also — HashingVectorizer.Save, HashingVectorizer.LoadAsync.