Earlier quoted context omitted.
That was my initial struggle as well coming into Go (I have worked for several years in C# & Java). You learn to work around this limitation using interfaces for both function parameters and return types. Frankly, I have had to do a little more explicit typecasting that I would have liked (going from interfaces to the actual type) but it is ok.
Are you saying that making sure the type is correct (just before the cast) becomes the programmer's responsibility? How often does this happen?
Nope. This mostly becomes a problem if you like to be DRY and try to replace generics (type T) kind of functionality with interfaces. For e.g., I have a method, which does the classic, lookup from cache first before hitting the actual db. In C#, you can use
public T Get(int id, string cacheKey) {
}
In Go, you have to return an interface (and ideally an error)
Here would be the equivalent,
v, err := s.Get(id int, cacheKey string)
if err != nil {
//Handle error here
}
if v == nil || v.(*models.User) == nil {
return nil, http.StatusNotFound
}