当 x.toString 失败时，ScalaRunTime.stringOf(x) 如何不失败? [英] How is ScalaRunTime.stringOf(x) not failing when x.toString fails?

问题描述

在试图找出一些 joda-time DateTime(时间戳格式)问题的同时，我用

Whilst trying to figure out some joda-time DateTime (timestamp formatting) issues I opened a REPL with

scala -cp joda-time-2.3.jar

忘记添加joda-convert jar，最后得到一个

and forgot to add the joda-convert jar, and eventually got a

java.lang.AssertionError: assertion failed: org.joda.convert.ToString

(整个堆栈跟踪)

我能够将其简化为:

> scala -cp joda-time-2.3.jar
Welcome to Scala version 2.11.0 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_05).
Type in expressions to have them evaluated.
Type :help for more information.

scala> val dt = new org.joda.time.DateTime
warning: Class org.joda.convert.FromString not found - continuing with a stub.
warning: Class org.joda.convert.ToString not found - continuing with a stub.
warning: Class org.joda.convert.FromString not found - continuing with a stub.
warning: Class org.joda.convert.ToString not found - continuing with a stub.
dt: org.joda.time.DateTime = 2014-05-14T17:54:24.511+01:00

scala> scala.runtime.ScalaRunTime.stringOf(dt)
res0: String = 2014-05-14T17:54:24.511+01:00

scala> dt.toString
java.lang.AssertionError: assertion failed: org.joda.convert.ToString

ScalaRunTime.stringOf(dt) 如何在 dt.toString 失败的情况下成功?

How is ScalaRunTime.stringOf(dt) succeeding where dt.toString fails?

推荐答案

您没有发布堆栈跟踪，这是编译器崩溃而不是 joda 的失败断言.

You didn't post the stack trace, which is a compiler crash and not a failed assertion by joda.

REPL 在编译表达式时崩溃.

The REPL is crashing compiling the expression.

看起来 AbstractDateTime 有一个重载的 toString 方法，并且重载解析在通常的 toString 上的 @ToString 注释上崩溃().(ToString 的符号丢失.)

It looks like AbstractDateTime has an overloaded toString method, and overload resolution crashes on the @ToString annotation on the usual toString(). (The symbol for ToString is missing.)

但是stringOf(x: Any)当然只是在调用Object.toString().

显然有一些已知问题.最近的问题已修复.

在 2.10.4 上:

On 2.10.4:

scala> (dt: Any).toString
res0: String = 2014-05-14T11:56:21.794-07:00

scala> dt.toString
<console>:9: error: ambiguous reference to overloaded definition,
both method toString in class AbstractDateTime of type (x$1: String, x$2: java.util.Locale)String
and  method toString in class AbstractDateTime of type (x$1: String)String
match expected type ?
              dt.toString
                 ^

scala> dt.toString()  // crashes

2.10.3 比较颠簸，并声称 加载 DateTime 时出错，类文件损坏.

2.10.3 is bumpier and claims error while loading DateTime, class file is broken.

崩溃发生在 2.11.0.

The crash is on 2.11.0.

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