将元组添加到集合不起作用 [英] Adding a tuple to a set does not work

问题描述

scala> val set = scala.collection.mutable.Set[(Int, Int)]()
set: scala.collection.mutable.Set[(Int, Int)] = Set()

scala> set += (3, 4)
<console>:9: error: type mismatch;
 found   : Int(3)
 required: (Int, Int)
              set += (3, 4)
                  ^

scala> set += Tuple2(3, 4)
res5: set.type = Set((3,4))

添加 (3, 4) 不起作用 - 为什么?

Adding (3, 4) does not work - why ?

通常，(3, 4) 也表示具有两个元素的元组.

Normally, (3, 4) also represents a tuple with two elements.

推荐答案

问题在于它存在于Set trait a method +(elem1: A, elem2: A, elems: A+) 编译器被它弄糊涂了.它实际上认为您尝试将此方法与 2 个 Int 参数一起使用，而不是像预期的那样与元组一起使用.

The issue is that it exists in the Set trait a method +(elem1: A, elem2: A, elems: A+) and the compiler is confused by it. It actually believes that you try to use this method with 2 Int parameters instead of using it with a tuple, as expected.

您可以使用:set += (3 -> 4) 或 set += ((3, 4))

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