OpenJDK mailing list: Null-safety and value types

Re:OpenJDK mailing list: Null-safety and value types by aardvark179 on Tuesday February 07, 2023 @08:12PM (#34702693)

Reference types probably can’t be made non-billable by default as that would break too much. But

  String! myString = “Definitely not null”;

doesn’t look too bad.

Edit: it’s worth saying that a lot of careful thought around compatibility goes into features like this. That means the core libraries should be able to transition to non-billable types where this is already a run time requirement, and existing compiled jars must continue to work.

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Re:OpenJDK mailing list: Null-safety and value types by vips7L on Tuesday February 07, 2023 @09:10PM (#34703193)

I don’t think anyone would really use String! everywhere.

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Re:OpenJDK mailing list: Null-safety and value types by aardvark179 on Wednesday February 08, 2023 @03:26AM (#34705567)

I think you’ll see it creep into parameter types in the core JDK and it will work its way out from there.

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Re:OpenJDK mailing list: Null-safety and value types by kaba0 on Wednesday February 08, 2023 @12:45AM (#34704588)

I think it can work in a binary-additive way — the class file gets a new attribute for nullness information, while missing it (older class files) default to “unspecified”. That can be safely consumed by new code, which will get the updated syntax with a new option (specified on a module/package/class basis) where ‘T’ means ‘T!’ and that should be a proper subset of previously compiling code, so I don’t think anything would break that way. Similarly to how generics and unchecked warnings were rolled out.

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