Why was constness removed from Java and C#?

后端 未结 5 2021
予麋鹿
予麋鹿 2021-02-20 00:45

I know this has been discussed many times, but I am not sure I really understand why Java and C# designers chose to omit this feature from these languages. I am not int

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  •  挽巷
    挽巷 (楼主)
    2021-02-20 01:02

    In this interview, Anders said:

    Anders Hejlsberg: Yes. With respect to const, it's interesting, because we hear that complaint all the time too: "Why don't you have const?" Implicit in the question is, "Why don't you have const that is enforced by the runtime?" That's really what people are asking, although they don't come out and say it that way.

    The reason that const works in C++ is because you can cast it away. If you couldn't cast it away, then your world would suck. If you declare a method that takes a const Bla, you could pass it a non-const Bla. But if it's the other way around you can't. If you declare a method that takes a non-const Bla, you can't pass it a const Bla. So now you're stuck. So you gradually need a const version of everything that isn't const, and you end up with a shadow world. In C++ you get away with it, because as with anything in C++ it is purely optional whether you want this check or not. You can just whack the constness away if you don't like it.

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