Is default(CancellationToken) equivalent to CancellationToken.None?（转载）

问

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Looking at the implementation of CancellationToken.None, it is simply returning default(CancellationToken). However, I see no reference in CancellationToken's documentation that the two are equivalent.
I'd like to offer an API like this but not until I'm sure it'll always work:

Task DoSomething(CancellationToken token = default(CancellationToken))

Is it defined behavior that default(CancellationToken) is the same as CancellationToken.None, or is this just an implementation detail?

答1

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They are the same. Check source code

public static CancellationToken None
{
    get { return default(CancellationToken); }
}

From https://referencesource.microsoft.com/#mscorlib/system/threading/CancellationToken.cs,36b17ded8b1a228c

答2

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After filing an issue with corefx, the documentation remarks have been updated to make this a guaranteed feature:

You can also use the C# default(CancellationToken) statement to create an empty cancellation token.

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