.delegate 在 groovy 中是什么意思? [英] What does .delegate mean in groovy?

问题描述

我找到了这个代码片段:

I found this code snippet:

def say = {println m}
say.delegate = [m:2]
say()

这显然打印了 2.它是如何工作的?在哪里可以找到关于 .delegate 的文档?Google 将我带到了完全没有提及 .delegate 的 Delegate Transformation 页面.

That apperantly prints 2. How does it work? Where can find documentation about .delegate? Google led me to the Delegate Transformation page that doesn't mention .delegate at all.

推荐答案

闭包的委托是一个对象，用于解析无法在闭包本身的主体内解析的引用.如果你的例子是这样写的:

The delegate of a closure is an object that is used to resolve references that cannot be resolved within the body of the closure itself. If your example was written like this instead:

def say = {
  def m = 'hello'
  println m
}
say.delegate = [m:2]
say()

它打印 'hello'，因为 m 可以在闭包内解析.然而，当 m 没有在闭包中定义时，

It prints 'hello', because m can be resolved within the closure. However, when m is not defined within the closure,

def say = {
  println m
}
say.delegate = [m:2]
say()

delegate 用于解析引用，在这种情况下，delegate 是一个映射 mMap代码>到2.

the delegate is used to resolve the reference, and in this case the delegate is a Map that maps m to 2.

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