golang how can I use struct name as map key

Question

type A struct {
    a1 int
    a2 string
}
type B struct {
    b1 int
    b2 string
}
type C struct {
    c1 int
    c2 string
}

there are 3 structs, I want put the names into a map as key, and process func as map value

(instead of type-switch)

input arg is a interface, use for loop to judge what struct this interface is. And process this arg by process func in map value. about:

var funcMap map[structName]func(arg){A:processA, B:processB, C:processC}

func testFunc(arg) {
    for k, v in range funcMap {
        if k == reflect.TypeOf(arg) {
            v(arg)
        }
    }
}

how can I build this map??? hope code, thanks! (^o^)

colm.anseo · Accepted Answer · 2021-09-16 14:26:18Z

3

You want to index your map on reflect.Type:

type funcMapType map[reflect.Type]func(interface{})

var funcMap funcMapType

then to register a type with a function:

funcMap[reflect.TypeOf(A{})] = func(v interface{}) { log.Println("found A") }

if your function needs to modify the struct, you'll need to register a pointer to the struct type:

funcMap[reflect.TypeOf(&A{})] = func(v interface{}) { log.Println("found *A") }

https://play.golang.org/p/LKramgSc_gz

edited Sep 16, 2021 at 14:26

answered Sep 16, 2021 at 13:07

colm.anseo

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3 Comments

blackgreen Over a year ago

for other readers: don't forget that reflect.TypeOf(A{}) != reflect.TypeOf(&A{}). Types must be identical

xiangyuhaoaizcm Over a year ago

how to handle pointer to struct as key? example: *A?

colm.anseo Over a year ago

@xiangyuhaoaizcm updated answer & playground-link with pointer logic.

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