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How To Implement an AsyncInit Interface

This topic details the steps necessary for defining a type that implements an AsyncInit interface.

In some cases, a type cannot be derived from a particular AsyncInitBase or CancelableAsyncInitBase, e.g. when it must derive from a predefined base class. In such scenarios IAsyncInit and ICancelableAsyncInit should be used instead.

  1. Determine the types of the initialization arguments (if any), e.g. IProgress<long>.

  2. Import the AsyncInit namespace:

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    using Ditto.AsyncInit;

  3. Implement the corresponding IAsyncInit or ICancelableAsyncInit(recommended):

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    class UniversalAnswerService : ICancelableAsyncInit<IProgress<long>>
{
    public int Answer { get; private set; }

    async Task ICancelableAsyncInit<IProgress<long>>.InitAsync(IProgress<long> progress, CancellationToken cancellationToken)
    {
        await Task.Delay(TimeSpan.FromDays(7500000 * 365.25), cancellationToken);
        Answer = 42;
    }
}

  4. Implement a private parameterless constructor:

    C#
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    private UniversalAnswerService()
{
}

  5. Implement a CreateAsync() method:

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    public async Task<UniversalAnswerService> CreateAsync(IProgress<long> progress, CancellationToken cancellationToken)
{
    return AsyncActivator.CreateAsync<UniversalAnswerService, IProgress<long>>(progress, cancellationToken);
}
Your class may now be consumed asynchronously:
Example
C#
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var service = await UniversalAnswerService.CreateAsync(progress, cancellationToken);
var answer = service.Answer;
See Also