ValueTuples是否适合用作字典键？ [英] Are ValueTuples suitable as dictionary keys?

问题描述

我认为这可能是一本便捷的字典：

I'm thinking this could be a convenient dictionary:

var myDict = new Dictionary<(int, int), bool>();

散列是什么样的？

等效的密钥类型是什么（

What would the hashes look like?
What would the equivalent key type (struct) look like?

推荐答案

是的，很好。 ValueTuple< ...> 家族是一组定义良好的规则结构，它们具有正确的相等性和哈希码行为，可以用作字典键。有一个轻微警告，它们是可变的而不是不可变的，但是由于存在复制语义，因此在这种情况下并不会真正影响它们（这意味着：在拥有密钥之后，您不能再更改密钥了。已添加，因为您只更改了键的不同副本；这与可变类作为键的问题非常不同）。您可以在此处查看代码。

Yes, that's fine. The ValueTuple<...> family is a well-defined set of regular structs with the correct equality and hash-code behaviour to work as dictionary keys. There is a slight caveat in that they are mutable rather than immutable, but that doesn't really impact them in this context thanks to copy semantics (which means: you can't change the key after it has been added, as you're only changing a different copy of the key; this is very different to the problem with mutable classes as keys). You can see the code here.

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