Closureをいじってみた https://gist.github.com/1342315 written by @mike_neck #gdk48 #jggugcamp

TestClosure.groovy

println 'Closure のおもろいところ'
println '基本'
[1,2,3,4].each { println it }

println 'オブジェクトのプロパティを表示する'
class Person {
    def firstName
    def middleName
    def lastName
    def age
    def address
    @Override each(Closure clsr) {
        [this.firstName, this.middleName, this.lastName, this.age, this.address].each {clsr(it)}
    }
}

def mike = new Person(firstName : 'mike', middleName : '_', lastName : 'neck', age : 34, address : '野良')
def list = []
mike.each { list << it }
list.sort().each {println it}

println 'Closure を別で定義する'
def clsr = {
    println it
}

[1,2,3,4].each(clsr)

println 'Closure を返す(1)'
Integer.metaClass.define {
    closure {int arg ->
        return {delegate + arg as int}
    }
}
int my = 10
println 10.closure(1)().closure(1)().closure(1)()

println 'Closure を返す(2)'
Integer.metaClass.define {
    inc {
        return { return delegate + 1 as int}
    }
}

int inc = 0
println inc.inc()().inc()().inc()().inc()()

println 'Closure でClosureを返す(安全)'
def counter = {
    def bs = 0
    return {bs++}
}
def clo1 = counter()
def clo2 = counter()
10.times{
    println clo1()
    println clo2()
}

println 'Closure でClosureを返す(安全でない)'
def notSafeCounter = {
    _cnt = 0
    return { _cnt++ }
}
def unSafe1 = notSafeCounter()
def unSafe2 = notSafeCounter()
10.times {
    println unSafe1()
    println unSafe2()
}

結果.txt

Closure のおもろいところ
基本
1
2
3
4
オブジェクトのプロパティを表示する
34
_
mike
neck
野良
Closure を別で定義する
1
2
3
4
Closure を返す(1)
13
Closure を返す(2)
4
Closure でClosureを返す(安全)
0
0
1
1
2
2
3
3
4
4
5
5
6
6
7
7
8
8
9
9
Closure でClosureを返す(安全でない)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19