如何使结构域成为列表中的值？

Question

I have a list of access rights:

const (
    Everyone = 0
    Owner = 1
    Administrator = 2
)

And a struct representing Routes:

type Route struct {
    Name        string
    Method      string
    Pattern     string
    HandlerFunc http.HandlerFunc
    AccessLevel uint64
}

How can I restrict AccessLevel field value of the Route struct be only one of those const from above?

Answer 1

You can't. Go doesn't support enums. However, you can get close to it. Just introduce a separate type for your access level:

type AccessLevel uint64

and make the consts be of the type:

const (
    Everyone      AccessLevel = 0
    Owner                     = 1
    Administrator             = 2
)

Then define the Field to be of that type:

type Route struct {
    // ...
    AccessLevel AccessLevel
}

Now you can assign those consts, but not a "normal" uint64.

The caveat is that you can still type convert a uint64 to a AccessLevel via AccessLevel(1234).