Golang Switch变量范围

Question

I'm trying to figure out simple switch in Golang and I'm stuck with variable scope.

var body string
var errs error
req := gorequest.New()
var resp gorequest.Response
switch verb {
case 0:
    resp, body, errs := req.Get(suburl).
        Set("X-Auth-Token", d.Token).
        Set("Content-type", "application/json").
        End()
}
if errs != nil {
    return &ConnResponse{resp.StatusCode, body, fmt.Errorf("%s", errs)}
}

I've declared resp, body, errs and req before switch and I've thought that they will be available after the switch body. What compiler returns is below errors (from the case declaration)

# command-line-arguments
./conn.go:135:3: resp declared and not used
./conn.go:135:9: body declared and not used
./conn.go:135:15: errs declared and not used

So I'm curious is the variable scope inside switch body is somehow different from declared in function? How would this piece of code look like to be able to get access to data after switch body.

Answer 1

Your issue is in this line:

resp, body, errs := req.Get(suburl)

The short variable declaration operator := creates new variables and assigns values to them. These new variables are said to "shadow" the variables you created in the outer scope, because they have the same names and thus they "hide" the outer-scoped variables from within that scope. To fix the issue, just assign the values to your existing variables from the outer scope, instead of creating new ones:

resp, body, errs = req.Get(suburl)

Note the use here of assignment = instead of short declaration :=.