scala - Scala for 循环可以修改其范围之外的变量吗？

Question

例如假设我有以下内容

  var lastSecurity = ""

  def allSecurities = for {
    security <- lastTrade.keySet.toList
    lastSecurity = security
  } yield security

眼下

lastSecurity = security

似乎是在范围内创建一个新变量，而不是修改第一行代码中声明的变量。

Answer 1

试试这个:

var lastSecurity = ""

def allSecurities = for {
  security <- lastTrade.keySet.toList
} yield {
  lastSecurity = security
  security
}