调用不同对象的闭包？ [英] Calling closure on different object?

问题描述

假设我有这个类：

class MyClass {
    int myInt

    MyClass(myInt) {
        this.myInt = myInt
    }

    def myMethod() {
        print this.myInt
    }
}

和某处：

def myClass1 = new MyClass(1)
def myMethodClosure = myClass1.&myMethod
def myClass2 = new MyClass(2)

现在如果我调用 myMethodClosure（），它会调用 myMethod ）在 myClass1 实例将打印1.我想要的是调用相同的 myMethodClosure 但是在不同的实例上，在这种情况下在 myClass2 ，所以它可以打印2.这是可能吗？

Now if I call myMethodClosure() it will call myMethod() on myClass1 instance which will print 1. What I want is to call the same myMethodClosure but on a different instance, in this case on myClass2 so it can print 2. Is this possible?

我尝试使用 setDelegate（），但它不工作。我还看到在闭包类中有字段 thisObject ，但它没有setter，只有一个getter。

I have tried using setDelegate(), but it does not work. I have also seen that there is field thisObject inside the closure class, but it does not have a setter, only a getter.

推荐答案

有两种方法添加到Groovy以帮助Closures序列化， dehydrate 和 rehydrate 。基本上，他们剥离（并重构）一个Closure的所有者， thisObject 和委托。在此示例中，您可以执行：

There were two methods added to Groovy to aid serialization of Closures, dehydrate and rehydrate. Basically, they strip (and reconstruct) a Closure's owner, thisObject and delegate. In this example, you could do:

myMethodClosure.rehydrate( myClass2, myClass2, myClass2 )()

然而，要获得输出 2 我会警惕这样做，因为这不是该方法的目的，可能会有严重的不可预见的后果。

To get the output 2, however I'd be wary about doing this as it is not what the method was intended for and there could be serious unforeseen consequences.

更好的解决方案可能是写一个工厂方法，为 MyClass 的给定实例获取方法引用。可能有其他更好的解决方案，但这取决于你所处的情况（我怀疑这个问题中的例子没有显示）

A better solution would probably be to write a factory method that gets a method reference for the given instance of MyClass. There may be other -- better -- solutions, but it depends on the situation you are in (that I suspect is not shown by the example in the question)

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