alt Hacker NewsFunctionally they don't - java is just catching up with (by now) ancient practice.
The false dichotomy of
> A struct in C# has identity and mutation, so the semantics of copying on assignment or passing have to be precisely defined, which gives a heavier model for the programmer and less freedom for the runtime.
Doesn't really match with what they're describing. While yes, it will not have identity in a java class ref sense, it of course will still have identity in being a unique structure in memory at a certain address. This is just splitting hairs about Java nomenclature.
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I don't wanna badmouth Java people, but how they push the idea that this thing is some sort of genuine breakthrough that took multiple PhDs years of cutting-edge research to implement, when in fact they basically copied what .NET did from basically year 1, is not a good look.
Again, not trying to turn this into a .NET vs Java thing, I'd have been much happier if they reached some new and interesting conclusions.
> it of course will still have identity in being a unique structure in memory
No, it will not. The design allows multiple objects to share one structure in memory across multiple records, or not have such a structure at all (see Scalarization in the article).