Question

在Groovy类中，我希望通过getter和setter将内部DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(10)) { self.toggleLikeSubject.onNext() }属性公开为String。我希望该属性的行为就像我可以使用List添加元素的常规列表属性。但它不起作用，我必须使用解决方法obj.list << newElement。

还有其他方法可以在Groovy中完成这个技巧吗？在类中实现的任何方法，将在使用obj.list = obj.list << newElement运算符时调用？

代码示例：

<<

Answer 1

Consider the following:

class Test {
    String internal = 'a,b,c'

    List getList() {
        def list = internal.split(',') as List

        // this will override so:
        // << 'd'       becomes appendToList(['d'])
        // << ['e','f'] becomes appendToList(['e','f'])
        list.metaClass.leftShift = { def x ->
            this.appendToList([x].flatten())
        } 

        return list
    }

    void appendToList(List list) {
        internal = internal + "," + list.join(',')
    }

    void setList(List list) {
        internal = list.join(',')
    }
}

Note it handles both cases of (a) one item (b) a list of items

def t = new Test()
t.list << 'd'
assert ['a','b','c','d'] == t.list
t.list << ['e','f']
assert ['a','b','c','d','e','f'] == t.list
t.list = ['x','y']
assert ['x', 'y'] == t.list

Answer 2

尝试使用以下代码

Test t = new Test()
 List list = t.getList()
list << 'd'

println list.dump()

Groovy - 仅通过getter-setter附加到列表中

2 个答案: