duanfei1975 2015-06-26 17:52
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在golang中切换基于枚举/基于iota的类型

I defined an enumeration and struct type like so:

type NodeType int
const (
        City NodeType = iota
        Town
        Village
)

type AreaNode struct {
        Location Coord2D
        Type NodeType
}

and now I'm iterating over a series of nodes that each have a type

if node, ok := area.Nodes[coord]; ok {
    switch node.Type {
        case node.Type == City:
            // do something for City
        case node.Type == Town:
            // do something for Town
        case node.Type == Outpost:
            // do something for Outpost
    }
}

However I'm getting an error: incompatible types in binary expression.

How can I resolve this?

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1条回答 默认 最新

  • dtueufe82643 2015-06-26 18:00
    关注

    you either do a switch with no value, and put comparison expressions in each case, or you treat each case as a == for the checked value. e.g.:

    if node, ok := area.Nodes[coord]; ok {
        switch node.Type {
            case  City:
                // do something for City
            case Town:
                // do something for Town
            case Outpost:
                // do something for Outpost
        }
    }
    

    The other switch syntax is used when you're switching between conditions that are not based on a single value. e.g.

    switch {
        case node.Type == City:
            // do something for City
        case node.OtherParam == "foo":
            ///
    }
    

    Which means basically you're switching between binary conditions. Personally, I use it just to remove clutter from long if/else blocks that don't rely on a single value, but I rarely use it.

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
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