[英]Groovy: how to get the value of a ?private? closure variable
I have a closure thats working great, but sometimes I would like to get the final value of a temporary variable I define in the closure. 我的闭包效果很好,但是有时我想获得在闭包中定义的临时变量的最终值。 Example: 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
Is this somehow possible? 这可能吗?
You can store the state in the closure's owner or delegate. 您可以将状态存储在闭包的所有者或委托中。
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
If you want to control what object the state goes into, you can override the closure's delegate. 如果要控制状态进入的对象,则可以覆盖闭包的委托。 For example: 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
No, there's no way of getting the variable, as the closure just returns a single result (so somclosure(2).howDoIGetThis
can't work), and there's no way to get a handle on the closure instance after it has been run... 不,没有办法获取变量,因为闭包仅返回一个结果(因此somclosure(2).howDoIGetThis
不能工作),并且在闭包实例运行后也无法获取句柄。 ..
The best I can think of, is to return multiple values from the Closure like so: 我能想到的最好的办法是从Closure返回多个值,如下所示:
def someClosure = {Number input->
def howDoIGetThis = input + 4
[ 2 * input, howDoIGetThis ]
}
def (normalWay, myFantasy) = someClosure(2)
assert normalWay == 4
assert myFantasy == 6
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