3个等于或等于大小写运算符 [英] 3 Equals or Case Equality operator

问题描述

在Ruby中，整数=== 5 返回 true 。同样， String === karthik 返回 true 。

但是， 5 ===整数返回 false 。和 karthik ===字符串。

为什么运算符不是可交换的？

In Ruby Integer === 5 returns true. Similarly String === "karthik" returns true.
However, 5 === Integer returns false. And "karthik" === String.
Why is the operator not commutative?

推荐答案

简单的答案是：因为这没有意义。运算符描述的关系不是可交换的，为什么运算符应该是？

The simple answer is: because it doesn't make sense. The relationship the operator describes is not commutative, why should the operator be?

仅看您自己的示例： 5 是一个整数。但是 Integer 是 5 吗？甚至 mean 是什么？

Just look at your own examples: 5 is an Integer. But is Integer a 5? What does that even mean?

=== 是 case包含运算符

=== is the case subsumption operator, and subsumption doesn't commute.

大小写包含运算符使用等号的事实，通常称为三等号， threequals 或 case equal 运算符非常不幸，因为它不仅没有绝对没有什么与平等有关，但它也不符合平等所遵循的许多定律，例如传递性和您提到的可交换性。

The fact that the case subsumption operator uses equals signs, and that it is usually called the triple equals, threequals or case equality operator is terribly unfortunate since it not only has absolutely nothing to do with equality, but it also does not conform to many of the laws that equality conforms to, such as transitivity and as you mentioned commutativity.

关于 === 参见

• === 运算符在Ruby中做什么？


• === 与 == 在Ruby中


• Integer ===如何3 工作？

• What does the === operator do in Ruby?
• === vs. == in Ruby
• How does Integer === 3 work?

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