Implement cloneable interface in ndarrays

[mattpap]

fixes #13226

[codecov]

Codecov Report

Merging #13232 (1f5f145) into branch-3.3 (c199eda) will not change coverage.
The diff coverage is n/a.

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  Hits            18577    18577           
  Misses           1520     1520           

[bryevdv]

Are users expected to use Cloner directly? If that's the case we would at least need an example that demonstrates this usage, otherwise there is no way users would know about it. I guess I was expecting a .clone() method (which would still need to be demonstrated explicitly)

[mattpap]

I don't expect many users to currently use this at all. This is an internal API right now, though users can import and use it. So currently it is the expectation to use Cloner class. There is no .clone() method, because there is no need to make bokehjs' classes heavier than they already and also cloning is a very expensive operation, so forcing explicit usage may make the user of this API reflect whether this is what they really ought to do. Of course at some point it would be good to expose this as a part of a public API, under the broad umbrella of TS/JS API.

[bryevdv]

@mattpap I ask because the issue this PR claims to fix was an unfulfilled need brought by a user. What is the guidance to give to that user to solve their problem?

If this PR does not offer them a solution then it should not close the issue.

[mattpap]

Contradicting my earlier statement, there's already HasProps.clone() method, which invokes Cloner class, so this PR ineed fixes the issue. I forgot this method actually exists.

[bryevdv]

@mattpap 👍 if you can also give a line or two of specific guidance to the OP I am sure it would be appreciated