Go - how to explicitly state that a structure is implementing an interface?
Method 2 is the correct one, method 1 you're just embedding a type and overriding its function. If you forget to override it, you will end up with a nil pointer dereference.
I have rarely needed to declare this, because there is almost always somewhere in my package where I am using the struct as the interface. I tend to follow the pattern of keeping my structs unexposed where possible, and providing them only through "constructor" functions.
type Foo interface{
Foo()
}
type bar struct {}
func (b *bar)Foo() {}
func NewBar() Foo{
return &bar{}
}
If bar
does not satisfy Foo
, this will not compile. Rather than add constructs to declare that the type implements the interface, I just make sure that my code uses it as the interface at some point.