interfaces
functions that different classes can implement
Key aspects of Unreal Engine 5 Interfaces:
-
Definition of Behavior, Not Implementation:
Interfaces declare functions without providing their implementation. They specify what a class should do, not how it should do it.
-
Common Functionality for Diverse Classes:
Interfaces enable a group of classes to share a common set of functions, even if they have no common ancestor other than UObject. For example, an IInteractable interface could define an OnInteract() function, which different objects like doors, NPCs, or pickup items could implement with their unique interaction logic.
-
Decoupling and Reduced Dependencies:
By using interfaces, you can interact with objects based on their implemented interfaces rather than needing direct references or casting to specific classes. This reduces tight coupling and makes your code more flexible and easier to maintain.
-
Blueprint Interfaces:
-
Created as separate Blueprint assets in the Content Browser.
-
Contain one or more "message functions" which have no logic themselves but can have inputs and outputs.
-
Implemented in other Blueprints through their Class Settings, allowing those Blueprints to provide their own implementation for the interface functions.
-
-
Alternatives to Casting:
Interfaces offer a more efficient and scalable alternative to extensive casting, especially when dealing with a variety of objects that share a common behavior. Casting can be memory-intensive and create hard references, which interfaces help to avoid.
-
Communication Mechanism:
Interfaces allow you to call a function on an actor, and if that actor implements the corresponding interface, its specific implementation of that function will be executed. If it doesn't implement the interface, nothing happens.
Things to Remember
Common Best Practice
Embrace Object-Oriented Principles
Use interfaces when multiple, unrelated classes need to share a common set of functions, but their specific implementations will differ (e.g., Interactable for doors, switches, and items).
Design for Clarity and Modularity
Create separate interfaces for distinct functionalities rather than a single "mega-interface." This improves organization, readability, and prevents blueprints from being cluttered with irrelevant interface functions.
Optimize for Performance and Memory
Avoid Hard References. Interfaces allow for generic actor references, eliminating the need for casting to specific Blueprint classes and preventing unnecessary loading of assets into memory. Clean these up when you're done to prevent memory leaks.
Implementation Considerations 01
Blueprint Callable Functions:
Define interface functions as BlueprintCallable to enable their use within Blueprints. Functions without return values are treated as events.
Implementation Considerations 02
Testing and Validation:
Thoroughly test the interface functionality to ensure that all implementing classes behave as expected and that the interface messages are correctly received and processed.