groovy - Groovy 中静态闭包的访问值

Question

我想在静态闭包中存储一些属性，然后在方法调用期间访问它们:

class Person {  
static someMap = { key1: "value1", key2: "value2" }  
}

那么如何在 Person 中编写一个方法来检索这些存储的数据呢？

Answer 1

对于简单的情况，最好使用 map 。

如果你真的想把它作为一个闭包来评估(可能是为了创建你自己的 DSL)，你需要像 John 指出的那样稍微改变你的语法。这是使用 Builder 类来评估传递给构建器的任何内容中的“某物”闭包的一种方法。

它使用 groovy 元编程来拦截缺少方法/属性的调用并保存它们:

class SomethingBuilder {
    Map valueMap = [:]

    SomethingBuilder(object) {
        def callable = object.something
        callable.delegate = this
        callable.resolveStrategy = Closure.DELEGATE_FIRST
        callable()
    }

    def propertyMissing(String name) {
        return valueMap[name]
    }

    def propertyMissing(String name, value) {
        valueMap[name] = value
    }

    def methodMissing(String name, args) {
        if (args.size() == 1) {
            valueMap[name] = args[0]
        } else {
            valueMap[name] = args
        }
    }
}

class Person {
    static something = {
        key1 "value1"              // calls methodMissing("key1", ["value1"])
        key2("value2")             // calls methodMissing("key2", ["value2"])
        key3 = "value3"            // calls propertyMissing("key3", "value3")
        key4 "foo", "bar", "baz"   // calls methodMissing("key4", ["foo","bar","baz"])
    }
}

def builder = new SomethingBuilder(new Person())

assert "value1" == builder."key1"  // calls propertyMissing("key1")
assert "value2" == builder."key2"  // calls propertyMissing("key2")
assert "value3" == builder."key3"  // calls propertyMissing("key3")
assert ["foo", "bar", "baz"] == builder."key4"  // calls propertyMissing("key4")