Groovy:如何获取 ?private? 的值闭包变量

Question

我有一个工作得很好的闭包，但有时我想获取我在闭包中定义的临时变量的最终值。示例:

def someClosure = {Number input->
  def howDoIGetThis = input + 4
  return 2 * input
}

def normalWay = someClosure(2)
assert normalWay == 4

def myFantasy = someClosure(2).howDoIGetThis
assert myFantasy == 6

这有可能吗？

Answer 1

您可以将状态存储在闭包的所有者或委托(delegate)中。

def howDoIGetThis
def someClosure = {Number input ->
    howDoIGetThis = input + 4
    return input * 2
}

def normalWay = someClosure(2)
assert normalWay == 4

someClosure(2)
def myFantasy = howDoIGetThis
assert myFantasy == 6

如果你想控制状态进入哪个对象，你可以重写闭包的委托(delegate)。例如:

def closureState = [:]
def someClosure = {Number input ->
    delegate.howDoIGetThis = input + 4
    return input * 2
}
someClosure.delegate = closureState

def normalWay = someClosure(2)
assert normalWay == 4

someClosure(2)
def myFantasy = closureState.howDoIGetThis
assert myFantasy == 6