我使用Groovy类在DSL下工作,我需要覆盖/ overload ==运算符.但是
known issue,当类实现Comparable时,Groovy将为==运算符调用compareTo()方法.我正在寻找一些解决方法(不是AST转换),以使==做我想要的.
我有以下“玩具”情况：
class Base implements Comparable<Base>{
int a,b
Base(int a,int b) {
this.a = a
this.b = b
}
@Override
int compareTo(Base o) {
return a <=> o.a //compare only a
}
}
class BaseCategory {
static boolean equals(Base base,o) { //complete equals
if (o == null)
throw new NullPointerException()
if (o.getClass() != base.getClass())
return false
return base.a == o.a && base.b == o.b
}
static int compareTo(Base base,o) { //compatible with equals
int c = base.a <=> o.a;
if (c != 0)
return c
return base.b <=> o.b;
}
}
现在我跑的时候
use(BaseCategory) {
Base a = new Base(1,2)
Base b = new Base(1,3)
println a == b
println a <=> b
}
我得到了0和0,而不是假和-1.有没有解决方法？
解决方法
一个旧的Groovy bug
[1]
[2]将在3.0中修复.您的用例是否允许封装和委派？
class Base implements Comparable<Base>{
int a,b
@Override int compareTo(Base o) {
return a <=> o.a
}
}
class BaseDelegate {
@Delegate Base base
boolean equals(o) {
if (o == null)
throw new NullPointerException()
if (o.getClass() != base.getClass())
return false
return base.a == o.a && base.b == o.b
}
int compareTo(o) {
int c = base.a <=> o.a;
if (c != 0)
return c
return base.b <=> o.b;
}
}
测试：
def a = new Base(a: 1,b: 2) def b = new Base(a: 1,b: 3) assert (a == b) == true assert (a <=> b) == 0 def a1 = new BaseDelegate(base: a) def b1 = new BaseDelegate(base: b) assert (a1 == b1) == false assert (a1 <=> b1) == -1
