为什么 AnyVal 不能用于 isInstanceOf 检查? [英] Why can AnyVal not be used in an isInstanceOf check?

问题描述

我想知道，为什么 AnyVal 不能用于 isInstanceOf 检查?这种行为背后的原因是什么?

I was wondering, why AnyVal can not be used in an isInstanceOf check ? What is the reason behind this behavior ?

scala> val c = 't'
c: Char = t

scala> c.isInstanceOf[AnyVal]
<console>:12: error: type AnyVal cannot be used in a type pattern or isInstanceO
f test
             c.isInstanceOf[AnyVal]

推荐答案

AnyVal 在运行时不再存在.仅在编译时.换句话说，将 JVM 原语视为一流对象只是编译器的技巧".

AnyVal does not exist anymore at runtime. Only at compile-time. In other words, it's just a compiler "trick" to consider the JVM primitives as first-class objects.

然而，isInstanceOf 方法是在运行时执行的，所以它无法工作.因此编译器错误.

However, the isInstanceOf method is executed at runtime, so it cannot work. Hence the compiler error.

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