红宝石:种类?与 instance_of 对比?vs. is_a?

问题描述

有什么区别?我什么时候应该使用哪个?为什么有这么多?

What is the difference? When should I use which? Why are there so many of them?

推荐答案

kind_of? 和 is_a? 是同义词.

instance_of? 与其他两个不同，它仅在对象是该类的实例而非子类时才返回 true.

instance_of? is different from the other two in that it only returns true if the object is an instance of that exact class, not a subclass.

示例:

• "你好".is_a?Object 和 "hello".kind_of?Object 返回 true 因为 "hello" 是 String 而 String 是 对象.
• 但是"hello".instance_of?对象返回false.

• "hello".is_a? Object and "hello".kind_of? Object return true because "hello" is a String and String is a subclass of Object.
• However "hello".instance_of? Object returns false.

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