Question

Groovy似乎有一些非常不愉快的行为与“Groovy Beans”和闭包有关，这些行为会导致它在某些情况下掩盖局部变量。

这是已知的行为，是否有某些文档可以详细说明这些内容？我浪费了很多时间试图找出什么不起作用......

请考虑以下代码：

class TestClass {

    def doIt(Closure closure) {
        closure.setDelegate(this)
        closure.call()
    }

    def getRevision() {
        return "testclass revision"
    }
}

def testIt() {
    def revision = "testit revision"

    println "1: " + revision + " (expect: testit)"

    TestClass tester = new TestClass()
    tester.doIt {
        println "2: " + getRevision()  + " (expect: testclass)"
    }

    println "3: " + revision + " (expect: testit)"

    tester.doIt {
        println "4: " + revision + " (expect: testit)"
        revision = getRevision()
        println "5: " + revision + " (expect: testclass)"
        println "6: ${getRevision()} (expect: testclass)"
        println "7: " + getRevision() + " (expect: testclass)"
    }

    // expect to have been set to testclass value in previous closure
    println "8: " + revision + " (expect: testclass)"

    tester.doIt {
        println "9: ${getRevision()} (expect: testclass)"
        println "10: " + getRevision() + " (expect: testclass)"
    }

    println "11: " + revision + " (expect: testclass)"
}

testIt()

运行此代码会产生以下输出：

1: testit revision (expect: testit)
2: testclass revision (expect: testclass)
3: testit revision (expect: testit)
4: testit revision (expect: testit)
5: testit revision (expect: testclass)
6: testit revision (expect: testclass)
7: testit revision (expect: testclass)
8: testit revision (expect: testclass)
9: testclass revision (expect: testclass)
10: testclass revision (expect: testclass)
11: testit revision (expect: testclass)

我的主要问题是5/6/7。似乎只是在闭包中使用本地revision变量“隐藏”委托中的getRevision()方法，并将其替换为bean样式自动生成的getRevision()以匹配{{ 1}}“属性”。如果我不使用revision变量，则对revision的调用不会调用此bean行为。

任何有关文档的见解或链接都将受到赞赏！

Answer 1

可用于控制分辨率顺序的Groovy闭包have a resolveStrategy property。默认策略是从“拥有”对象中查找属性，并且只有在那里找不到它才能使用委托。我相信将其设置为DELEGATE_FIRST会得到您期望的行为。

自动属性getter，局部变量和闭包之间的Groovy冲突？

1 个答案: