Consider such function that accepts function as argument:
func f(arg func(I)){}
where I is interface.
Is there any way to pass into above function an argument of signature func(*T) where T implements I interface.
Now when I pass it, I have an error:
cannot use (type func(*T)) as type func(I) in argument
Here is playground: https://play.golang.org/p/7vilY4zkEzf
Use case is the following:
I write package that has f(a func(I), b I) function. Then user will import it as library.
As a next step, user will define a custom type T that implements I interface and a custom function with signature func(*T) . Then user will call library f function:
f(customFunction, customObject)
In turn, package will receive it and create a goroutine:
go customFunction(customObject)
The reason why goroutines are created "inside" package is that goroutine orchestration should be hold "under the hood".
No, the types need to be exact. Your example is especially broken because I isn't definitely convertible to *T, but it also wouldn't work the other way. If you're sure that the type of the I being passed to your function is *T, you could create wrapper function and pass that instead.
func wrapper(i I) {
t := i.(*T)
myRealFunc(t)
}