gistfile1.go

func wrapHandler(f func(user, request), perm int) func(request) {
    return func(r request) {
        user := getuser(r)
        if user.priv < perm {
            write("no permission foo'!")
        } else {
            f(user, r)
        }
    }
}

func userPage(user, request) { ... }

http.Handle("/someurl", wrapHandler(userPage, 1))