多个参数的隐式转换 [英] Implicit conversion for multiple parameters

问题描述

是否可以在Scala中对一组参数(而不将它们定义为某些类成员)实现隐式转换，例如

Is it possible to implement in Scala an implicit conversion for the group of parameters (without defining them as some class member) like

implicit def triple2One (x :Int, s :String, d :Double) =  x  // just as an example

这样我就可以在类似的代码中调用它

So that I would be able to call it in the code like

val x :Int = (1, "test", 2.0)

推荐答案

可能:

scala> implicit def iFromISD(isd: (Int, String, Double)): Int = isd._1
iFromISD: (isd: (Int, String, Double))Int

scala> val x: Int = (1, "two", 3.0)
x: Int = 1

自然，在生成的 val 上必须有一个类型注释，以驱动隐式转换的搜索和应用.

Naturally, there has to be a type annotation on the resulting val to drive the search for and application of the implicit conversion.

附录

在我看来，还有另一种方式不涉及可疑的隐式转换:

It occurs to me there's another way that doesn't involve dubious implicit conversions:

scala> val (y, _, _) = (1, "two", 3.0)
y: Int = 1

这篇关于多个参数的隐式转换的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！