Golang中的功能接口

Question

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".

Answer 1

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)
}