如何在没有无限递归的情况下检查'=='运算符超载中的空值?
以下将导致==运算符重载方法的无限递归
Foo foo1 = null;
Foo foo2 = new Foo();
Assert.IsFalse(foo1 == foo2);
public static bool operator ==(Foo foo1, Foo foo2) {
if (foo1 == null) return foo2 == null;
return foo1.Equals(foo2);
}
我如何检查空值?
使用ReferenceEquals
:
Foo foo1 = null;
Foo foo2 = new Foo();
Assert.IsFalse(foo1 == foo2);
public static bool operator ==(Foo foo1, Foo foo2) {
if (object.ReferenceEquals(null, foo1))
return object.ReferenceEquals(null, foo2);
return foo1.Equals(foo2);
}
在重载方法中转换为对象:
public static bool operator ==(Foo foo1, Foo foo2) {
if ((object) foo1 == null) return (object) foo2 == null;
return foo1.Equals(foo2);
}
使用ReferenceEquals
。 从MSDN论坛:
public static bool operator ==(Foo foo1, Foo foo2) {
if (ReferenceEquals(foo1, null)) return ReferenceEquals(foo2, null);
if (ReferenceEquals(foo2, null)) return false;
return foo1.field1 == foo2.field2;
}
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