Is there any basis for the names Shared and Default?

[zms9110750]

Some types provide entry points for static instance retrieval, but they have different names. What is the basis for choosing this name.

By the way, CollectionsMarshal.AsSpan()， This feature can be a LIst method or an extension method. Is there any basis for the common method of ultimately choosing to make him a separate class

[stephentoub]

By the way, CollectionsMarshal.AsSpan()， This feature can be a LIst method or an extension method. Is there any basis for the common method of ultimately choosing to make him a separate class

It's not as "safe" as the methods on List<>, as it provides access to the underlying storage, which make be invalidated (no longer associated with the list) when other changes are made to the list, e.g.

List<int> list = [1, 2];
Span<int> span = CollectionsMarshal.AsSpan(list);
span[0] = 42;
Console.WriteLine(list.Contains(42)); // will be true

list.AddRange([3, 4, 5, 6, 7, 8, 9, 10]);
span[0] = 84;
Console.WriteLine(list.Contains(84)); // may be false

[zms9110750]

So his significance is only to raise the threshold for use, making it not so simple for him to use?
To convey a message: use as little as possible?

[stephentoub]

It's to put it in a "Marshal" class in InteropServices, to highlight that it's about interacting with the implementation details of the type and doesn't have the same guarantees you'd expect from an instance method on List.

[huoyaoyuan]

Some types provide entry points for static instance retrieval, but they have different names. What is the basis for choosing this name.

Under my impressions, Instance is for stateless stuffs like EqualityComparer<T>, which is meaningless to create multiple instances.
Shared is for providing a global stateful instance to share between different users, for example Random.Shared or ArrayPool<T>.Shared.