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by cesarb
681 days ago
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That's still the case in pure Java code. The "Class.newInstance()" method is a public method on the core Java API, calling "MyClass.class.newInstance()" is mostly equivalent to "new MyClass()". And the generics trick in the "sneaky throws" article I linked is also pure Java code, without any calls to "sun.misc.Unsafe". |
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The generics hole is indeed interesting, but it's ultimately a known limitation of how generics were implemented in Java, the presence of type inference, and the design of the exception hierarchy, than an intentional feature. When inferring the type of T to apply in that example, there is no good unique solution: inferring T = Throwable would have been safer, but it makes many simple cases behave unexpectedly, especially with lambdas. Inferring T = RuntimeException is unexpected and unsafe, but in practice it makes many common cases be way more usable, so a call was made to do it, despite the hole.
C++'s templates wouldn't have a similar problem, as they actually instantiate the definition at compile time and can re-check it. Also, there is no equivalent issue to the ambiguous inference, because C++ doesn't do type inference of this kind at all, and anyway there is no problem of the exception hierarchy. Even if there were, C++ could also take the opposite choice than Java, and explicitly infer the safer option when both `noexcept` and `potentially-throws` were possible.
And of course Lombok is a tool for modifying the compilation of Java, so writing Lombok code is not exactly writing pure Java.