interface Animal { Eat(): void }
interface Dog extends Animal{ Bark():void }
interface Cat extends Animal{ Meow():void }
interface ComparerA<T> {
compareA: (a: T, b: T) => number;
}
interface ComparerB<T> {
compareA(a: T, b: T): number;
}
declare let animalA: ComparerA<Animal>;
declare let dogA: ComparerA<Dog>;
declare let animalB: ComparerB<Animal>;
declare let dogB: ComparerB<Dog>;
animalA = dogA; // 错误
dogA = animalA; // 正确
animalB = dogB; // 正确
dogB = animalB; // 正确
为什么: 和=> 声明出来的函数会有区别 一个是逆变 一个是双向协变呢?
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