将切片传播为args列表

Question

I have this func:

func Middleware(adapters ...interface{}) http.HandlerFunc {
    // ...
}

and I am trying to call it via:

middleware := []mw.Adapter{mw.Error(),mw.Auth("x-huru-api-token")}
router.HandleFunc("/person_data_field", 
mw.Middleware(middleware...,h.makeGetMany(v))).Methods("GET")

this doesn't compile though, I get:

In any case, I need to spread the slice so that it is sent as multiple arguments not just one arg...

With JS, it just looks like this:

const v = [1,2,3];

const f = function(...values){
    console.log(values);  // [1,2,3,4]
};

f(...v,4);

Answer 1

You can pass variadic arguments individually or as a single slice. You cannot mix and match. The slice element type must match the variadic argument type.

To fix the problem, put all of the variadic arguments in a slice of []interface{}:

middleware := []interface{}{mw.Error(),mw.Auth("x-huru-api-token"), h.makeGetMany(v)}
router.HandleFunc("/person_data_field", mw.Middleware(middleware...)).Methods("GET")

Use slice tricks if you cannot build the slice directly as shown in the previous snippet.

middleware := []mw.Adapter{mw.Error(),mw.Auth("x-huru-api-token")}
router.HandleFunc("/person_data_field", mw.Middleware(
    append(append([]interface{}{}, middleware...), h.makeGetMany(v)))).Methods("GET")