Question

我有一个全局变量ser，我需要在某些情况下删除它：

global ser
ser = ['some', 'stuff']

def reset_ser():
    print('deleting serial configuration...')
    del ser

如果我致电reset_ser()，我会收到错误消息：

UnboundLocalError: local variable 'ser' referenced before assignment

如果我将全局变量作为输入提供给函数我不会得到错误，但是变量不会被删除（我猜只是在函数本身内部）。有没有办法删除变量，或者我是否要覆盖它以摆脱它的内容？

Answer 1

在函数中使用global ser：

ser = "foo"
def reset_ser():
    global ser
    del ser

print(ser)
reset_ser()
print(ser)

输出：

foo
Traceback (most recent call last):
  File "test.py", line 8, in <module>
    print(ser)
NameError: name 'ser' is not defined

Answer 2

您可以使用以下命令将其从全局范围中删除：

object Example {

  sealed trait Status
  case object Student extends Status
  case object Unemployed extends Status
  case object Other extends Status

  object PoorStudent {
    def unapply(income: Int) = if (income <= 18000) Some(income) else None
  }

  object PoorUnemployed {
    def unapply(income: Int) = if (income <= 7000) Some(income) else None
  }

  object IncomeScoreRange {
    def unapply(score: Int, income: Double) =
      if (((score < 100 || score > 150) && income <= 8500) || (income <= 10500 && (100 to 167 contains score)))
        Some((score, income))
      else
        None
  }

  def compute(status: Option[Status], score: Option[Int], income: Option[Double]): String = {

    (status, score, income).zipped
      .collect {
        case (Student, _, PoorStudent(_))                    => "P"
        case (Unemployed, _, PoorUnemployed(_))              => "P"
        case (Other, IncomeScoreRange(_, _))                 => "P"
      }
      .headOption
      .getOrElse("F")
  }
}

更完整的例子：

del globals()['ser']

如何从函数内删除全局变量？

2 个答案: