试图了解Groovy中的运行时关闭/方法覆盖

Question

I wrote the following code to learn closure/method overwriting in groovy. I couldn't understand its behavior.

class AClass {
    def closure1 = { ->  println "hello from closure1 - ${this.toString()}" }

    def closure2 = { c1 ->
        print "closure2 { \n    "
        c1()
        println "}"
    }
}

def obj = new AClass()
print "1: "
obj.closure1()

//over write closure1
obj.metaClass.closure1 = { -> println "hello from *** overridden closure1 *** - ${this.toString()}".toUpperCase()}
print "\n2: "
obj.closure1() //To confirm closure1 was indeed overwritten

//call closure2
print "\n3: "
obj.closure2 (obj.closure1)
print "\n4: "
obj.closure2 {obj.closure1()}

I was expecting the two closure2 calls to generate the same result but apparently they don't.

Below is the result of running my code.

1: hello from closure1 - AClass@d706f19

2: HELLO FROM *** OVERRIDDEN CLOSURE1 *** - TESTMTDOVERRIDE@BE64738

3: closure2 { 
    hello from closure1 - AClass@d706f19
}

4: closure2 { 
    HELLO FROM *** OVERRIDDEN CLOSURE1 *** - TESTMTDOVERRIDE@BE64738
}

Answer 1

You have two different things here... A variable closure1 that holds a closure, and a method closure1 which you have added to the metaClass via a closure...

obj.closure2 (obj.closure1)

Calls closure2, and passes in the variable

obj.closure2 {obj.closure1()}

Passes a closure that calls the closure in the metaClass

They are very different things

You've just called them the same