Interfaces and Components - Javascript

Unity Engine
1

Hello,

I am creating several different components. But I would like all of these components to share a common interface so that I can call specific functions on them without having to know their data type. How can I achieve this in Javascript? I could use SendMessage, but I cannot retrieve return values with this method. I have heard about Interfaces, but I am not sure how to work with these in Javascript for this purpose.

Thanks in advance.

2 
interface SomeInterface {
    function DoSomething();
}

class SomeClass implements SomeInterface {
    function DoSomething() {

    }
}

Make sure your interface file name is not the same as the name of the interface contained within. Unity tries to turn it into a class and you’ll get reference errors.

3

Interesting to know. Thank you for the reply.

Perhaps I am missing something however, but I am not sure how that solves the problem. My aim was to be able to create a set of components, each with a different implementation, and be able to use the GetComponent function to retrieve a reference to any of those components by way of passing the Component base type as an argument (or some common type), and then to call a function on the returned component without knowing its sub-type, because all the components implemented a common interface. EG:

And then

It seems to me from your code though that a class implements an interface only by using the implements keyword in the class declaration. This is a problem, I think, because Javascript does not (as far as I know) allow me to edit the class declaration for a component. It creates one for me implicitly and does not show it in the source file. Presumably this means that I cannot make a component implement an interface. If I cannot make a component implement an interface, then presumably I cannot call a function on them unless I know their type after all?

Thanks.

4

Sure you can. Just because Unity does it for you doesn’t mean you can’t do it yourself.

This is perfectly ok.

class SomeClass extends MonoBehaviour implements SomeInterface {

}

I have heard some people talk about GetComponent on interfaces being unreliable and/or not working well in UnityScript. I’ve used it a bunch of times in C# to get a base class that a bunch of classes inherit from, but never done this specifically in UnityScript. Someone else might be able to speak more to that.