Groovy枚举-调用链

Question

我很惊讶地看到对枚举的链式调用是有效的。我碰巧有一个名为'name‘的枚举实例，当我忘记了括号时，它被引用了，而不是name()。枚举应该允许链式调用吗？使用Groovy 2.4.10 -参见下面的最后3个调用：

Groovy Shell (2.4.10, JVM: 1.8.0_121)
Type ':help' or ':h' for help.

groovy:000> public enum Compass { north, south }
===> true
groovy:000> Compass.north
===> north
groovy:000> Compass.north.name
ERROR groovy.lang.MissingPropertyException:
No such property: name for class: Compass
groovy:000> Compass.north.name()
===> north
groovy:000> public enum Compass { north, south, name }
===> true
groovy:000> Compass.north.name()
===> north
groovy:000> Compass.north.name
===> name
groovy:000> Compass.north.south
===> south
groovy:000> Compass.north.south.north
===> north

Answer 1

这是正确的。在Java语言中，枚举是同一类中静态字段之上语法糖(加上像values()和name()这样有用的东西)，因此，当您调用枚举字段时，您还有一个对该类的静态引用，它还可以访问其他类的字段：

class Compass {
    static NORTH = new Compass()
    static SOUTH = new Compass()
}


assert Compass.NORTH.SOUTH.NORTH == Compass.NORTH

def west = new Compass()
assert west.SOUTH == Compass.SOUTH