英文:
Golang interfaces to simplify dependencies?
问题
嗯，我对接口的概念有些困惑。
我正在使用一个处理mongodb的Go包，但我不想在每个模型中都导入该包。我希望尽可能多地使用标准库来管理我的子包（如模型）。所以我想定义一些接口，如下所示：
type m map[string]interface{}
type collectionSlice interface {
One(interface{}) error
}
type collection interface {
Upsert(interface{}, interface{}) (interface{}, error)
Find(interface{}) collectionSlice
}
type database interface {
C(string) collection
}
问题是，当我尝试使用以下函数时：
func FindItem(defindex int, d database) (*Item, error) {
通过将我的mgo.Database作为参数传递给使用这些接口的包中的函数：
item, err := dota.FindItem(int(defindex), ctx.Database)
我得到一个编译器错误：
controllers/handlers.go:35: cannot use ctx.Database (type *mgo.Database) as type dota.database in function argument:
*mgo.Database does not implement dota.database (wrong type for C method)
have C(string) *mgo.Collection
want C(string) dota.collection
我对这个概念有什么误解吗？
英文:
Hmmm, I'm having a problem wrapping my head around interfaces.
So I am using a Go package for handling my mongodb stuffs, but I don't want to import that package into every model and what not. I'd like to keep as many of my sub packages (like models) to just the standard library. So I thought I would lay out some interfaces like so:
type m map[string]interface{}
type collectionSlice interface {
One(interface{}) error
}
type collection interface {
Upsert(interface{}, interface{}) (interface{}, error)
Find(interface{}) collectionSlice
}
type database interface {
C(string) collection
}
The problem is, when I go to use a function like:
func FindItem(defindex int, d database) (*Item, error) {
that is found in the package that is using the interfaces by passing in my mgo.Database:
item, err := dota.FindItem(int(defindex), ctx.Database)
I get a compiler error:
controllers/handlers.go:35: cannot use ctx.Database (type *mgo.Database) as type dota.database in function argument:
*mgo.Database does not implement dota.database (wrong type for C method)
have C(string) *mgo.Collection
want C(string) dota.collection
What am I missing about this concept?
答案1
得分: 1
我收到了关于这个回答的回复，来自 golang-nuts。
我遇到的问题是方法必须具有完全相同的签名：
http://golang.org/doc/faq#t_and_equal_interface
感谢 golang-nuts 群组的 Jesse McNelis！
英文:
Got a reply to this answer on golang-nuts.
The issue I'm having is that the methods must have exactly the same signature:
http://golang.org/doc/faq#t_and_equal_interface
Thanks to Jesse McNelis on the golang-nuts group!
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