UnrealDI

Dependency Injection container for Unreal Engine. Container will take care of objects creation and their lifetime.

This implementation works on top of UObjects and UInterfaces.

Getting started

First, you need to setup your container and register some types into it:

// create builder object
FContainerBuilder Builder;

// register type UMyService as implementation of IMyService interface
Builder.RegisterType<UMyService>().As<IMyService>();
Builder.RegisterType<UMyOtherService>().As<IMyOtherService>();

// create container itself
UObjectContainer* Container = Builder.Build();

After that you can ask it to resolve some instances:

TScriptInterface<IMyService> MyService = Container->Resolve<IMyService>();
TScriptInterface<IMyOtherService> MyService = Container->Resolve<IMyOtherService>();

If you need IMyService in some other class, use InitDependencies. Container will automatically call this method when it creates the object and provide all requested dependencies

UCLASS()
class UMyOtherService : public UObject, public IMyOtherService
{
    GENERATED_BODY()
public:
    void InitDependencies(TScriptInterface<IMyService> InMyService)
    {
        // InMyService is always valid here, no need to check for it
        MyService = InMyService;

        MyService->DoSomething();
    }

private:
    // store reference to interface inside a UPROPERTY to protect it from GC
    UPROPERTY()
    TScriptInterface<IMyService> MyService;
};

If you want container to create only one instance of an object and pass it to others, use WeakSingleInstance or SingleInstance during registration:

Builder.RegisterType<UMyService>().As<IMyService>().SingleInstance();

Supported versions

Latest release of UnrealDI requires at least Unreal 5.1. For Unreal version 5.0 and below, please use Unreal DI v1.5.0
I test this plugin to work with the latest version of Unreal Engine and two versions before it. If you have any issues, please submit them here

Repository structure

This repository contains two plugins:

• UnrealDI — contains DI functionality to be used in game.
• UnrealDITests — contains Tests for main plugin and not intended for shipping.

Installation

1. Download latest release
2. Extract archive contents into your project /Plugins/UnrealDI folder
3. Generate project files and build

Acknowledgment

UnrealDI is heavily inspired by Hypodermic, but designed with Unreal Engine specifics in mind.