The explanation on why Java lets you use unnamed variables to prevent accidental use during deconstruction, but those unusuable variables still getting initialized by calling accessors, is a perfect example why I dislike the way Java implements improvements.

Every single, logical step that led to this hidden performance problem makes complete sense, because every improvement had to be its own tiny, contained improvement, but the end result is that `case Foo(int _, String _, User _, int age)` will still call three getters _just in case_ you're abusing the language to add side effects to accessors.

Perhaps even worse is the explanation that follows: if you don't mess up your accessors, the JVM _may_ decide to not call those accessors at runtime. So now the language itself has this weird performance impact to maintain backwards compatibility, but at runtime that backwards compatibility _may_ not exist and provide you with a performance improvement instead, negating the whole reason why backwards compatibility was added in the first place.

I like the improvements to Java, don't get me wrong. It's no longer the JDK 1.7 language poor enterprise programmers are stuck with. But if the Java people had come together and worked this out as one single feature, rather than five different ones, we wouldn't have needed to remember edge cases/a code analysis tool to remind us that using this intuitive language feature _may_ actually has a 3x performance impact depending on the mood the JVM is in today.