带下划线的Scala字符串插值 [英] Scala String Interpolation with Underscore

问题描述

我对Scala还是陌生的，因此可以随时指出文档的方向，但是我在研究中找不到该问题的答案.

I am new to Scala so feel free to point me in the direction of documentation but I was not able to find an answer to this question in my research.

我正在使用带有Spark2.2的 scala 2.11.8 ，并尝试使用内插法创建一个包含dateString1_dateString2(带下划线)的动态字符串，但是存在一些问题.

I am using scala 2.11.8 with Spark2.2 and trying to create a dynamic string containing dateString1_dateString2 (with underscores) using interpolation but having some issues.

val startDt = "20180405" 
val endDt = "20180505"

这似乎可行:

s"$startDt$endDt"
res62: String = 2018040520180505

但这失败了:

s"$startDt_$endDt"
<console>:27: error: not found: value startDt_
       s"$startDt_$endDt"
          ^

我希望这种简单的变通方法可以正常工作，但不会产生预期的结果:

I expected this simple workaround with escapes to work but does not produce desired results:

s"$startDt\\_$endDt"
res2: String = 20180405\_20180505

请注意，此问题不同于为什么不能使用_ ，因为该问题旨在寻找可行的字符串插值解决方案，而前一个问题则更多地关注标量内部.

Note that this question differs from Why can't _ be used inside of string interpolation? in that this question is looking to find a workable string interpolation solution while the previous question is much more internals-of-scala focused.

推荐答案

您可以使用花括号将其明确显示:

You can be explicit using curly braces:

@ s"${startDt}_${endDt}"
res11: String = "20180405_20180505"

您的代码:

s"$startDt_$endDt"

失败，因为startDt_是有效的标识符，并且scala尝试对不存在的变量进行插值.

fails since startDt_ is a valid identifier, and scala tries to interpolate that non-existant variable.

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