RFR: 8298318: (fs) APIs for handling filename extensions [v2]

[Anthony Vanelverdinghe]

On Mon, 20 Nov 2023 23:30:45 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> Add to `java.nio.file.Path` a method `getExtension` to retrieve the `Path`'s extension, and companion methods `removeExtension` and `addExtension`.
>
> Brian Burkhalter has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:
> 
>  - 8298318: Correct type in path.getExtension spec
>  - Merge
>  - 8298318: (fs) APIs for handling filename extensions

For the `.gitconfig` example, I just wanted to point out that the whole concept of a filename extension is merely an OS-specific convention. So I'd argue that the JDK should be neutral, rather than pick one specific convention. Since you mentioned "OS-specific behavior is not usually codified", the `Convention` enum I used is not an option, but the `getExtension` implementation could behave differently depending on its environment and specify something like `the exact definition of "extension" is implementation specific`.

About whether to include the dot: I'm not a mathematician, but intuitively I'd say that excluding it makes it impossible to implement the API in such a way that `equals(removeExtension().addExtension(getExtension()))` always holds. On the other hand, including it would make it trivial to do so.

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PR Comment: https://git.openjdk.org/jdk/pull/16226#issuecomment-1822276138