An interface function that returns values ​​from classes that implement the interface

[Diego101777]

I have interface with one function:

IInterface: {
TArray<IInterface*> GetItems();
}

And I have two classes that implements that interface and dependent on each other:

Class A: IInterface {
TArray<ClassB*> Items;

TArray<IInterface> GetItems() {
return Items;
    }

}

Class B: IInterface {
TArray<ClassA*> Items;

TArray<IInterface*> GetItems() {
return Items;
    }

}

But in editor I have an error:

Cannot convert value of type TArray<ClassA*> to return type TArray<IInterface*>

So I have a question: What the correct way to implement that behavior?

[3dRaven]

You can’t have an interface as an element of an array unless you use TScriptInterface

as mentioned in this thread

Any Object implementing an Interface as parameter

I’m not sure I understand what you want to do to be honest. Given the example code you showed, you cannot just call that function on any random object. You can only call it on an object which implements the interface, and therefore you already have to know whether it implements it or not, and already have a reference to it. It’s no different in Blueprint. Either way, both of these functions compiled fine for me - and gave me a node with an interface pin on the return. Obviously in this example…

But you can in this place simplify it by having the TArray hold a UObject (a base class) in the interface

I made an example project that demonstrates this with a implementation:

Intface.zip (35.5 KB)

Just regenerate the UPROJECT file (right click and generate solution)