Scala 类型参数被推断为元组 [英] Scala type parameter being inferred to tuple

问题描述

我突然遇到了这种(出乎我意料的)情况:

I suddenly came across this (unexpected to me) situation:

def method[T](x: T): T = x

scala> method(1)
res4: Int = 1

scala> method(1, 2)
res5: (Int, Int) = (1,2)

为什么在两个或更多参数的情况下，方法返回并推断出一个元组，但抛出有关参数列表的错误?是故意的吗?也许这种现象有名字?

Why in case of two and more parameters method returns and infers a tuple but throwing error about parameter list? Is it by intention? Maybe this phenomenon has a name?

推荐答案

% scala2.10 -Xlint

scala> def method[T](x: T): T = x
method: [T](x: T)T

scala> method(1)
res1: Int = 1

scala> method(1, 2)
<console>:9: warning: Adapting argument list by creating a 2-tuple: this may not be what you want.
        signature: method[T](x: T): T
  given arguments: 1, 2
 after adaptation: method((1, 2): (Int, Int))
              method(1, 2)
                    ^
res2: (Int, Int) = (1,2)

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