英文:
Is there a nice way to simulate a "Maybe" or "option" type in Go?
问题
我正在通过chan X发送回复给一个请求，其中X是一个结构体。这个请求是一个搜索操作，所以理想情况下我希望能够返回一个X，或者报告找不到。
在Haskell中，这将是一个Maybe X的任务，而在OCaml中则是一个x option。在Go中有没有合适的方法来做到这一点？我不返回一个指针（因为我返回的原始对象可能会被修改），所以我不能只返回nil。
**编辑：**目前我将其作为chan interface{}，然后发送一个X或nil，但这很丑陋并且违背了类型安全性。
英文:
I'm sending a reply to a request over a chan X, where X is a struct. The request is a search operation, so ideally I'd like to be able to return either an X, or report it wasn't found.
This would be a task for a Maybe X in Haskell or an x option in OCaml. Is there any decent way to do this in Go? I'm not returning a pointer (as the original object I'm returning might be modified later), so I can't just return nil.
Edit: right now I'm making it a chan interface{} and either sending an X or nil, but this is ugly and defeats type-safety.
答案1
得分: 16
我使用指针类型，其中：
Maybe X=*XNothing=nilJust x=&x
英文:
I use the pointer type, where:
Maybe X=*XNothing=nilJust x=&x
答案2
得分: 5
如果您正在使用interface {}，那么现在您实际上是返回一个指针。为什么不将interface {}更改为*X，并确保返回对象的副本呢？如果我理解您不使用chan *X的原因的话。
英文:
If you're using interface {} you're effectively returning a pointer now. Why not change interface {} to *X and make sure to return a copy of the object? If I understand your reasoning behind not using a chan *X, that is.
答案3
得分: 5
另一种方法是添加一个ok布尔值。你可以将其添加到X中，或者像struct {X; ok bool}这样包装X。
英文:
Another way would be to add an ok bool. You could either add it to X or wrap X, like struct {X; ok bool}
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