Dependencies

This page will cover how to retrieve singletons from inside other singletons, or anywhere else in your code.

Dependency Injection

The preferred way to get references to your singletons is by using dependency injection. Flamework uses a constructor-based DI system, which means you simply specify the dependencies in your constructor and Flamework will automatically pass them when creating the singleton.

When you request a dependency through dependency injection, Flamework will automatically determine the load order of your singletons.

import { OtherService } from "./otherService";

@Service()
export class MyService {
	constructor(private otherService: OtherService) {}

	method() {
		print(this.otherService.getName());
	}
}

Dependency Macro

If you cannot, or do not want to, use dependency injection then you can use the Dependency macro. The macro will grab a reference to your singleton and can be called from anywhere in your code, not just in other singletons.

Not Recommended

It is not recommended to use the Dependency macro.

While the Dependency macro can be more convenient, it can also harm your ability to stub, test or refactor your code. You should pass dependencies down through dependency injection, e.g through function arguments, Roact Contexts, etc.

The Dependency macro can also obfuscate the execution order of your singletons, as a dependency of a singleton might run after your singleton, as Flamework cannot statically know your singleton depends on another.

When Flamework releases v2.0, the Dependency macro may be removed or be unable to run in certain contexts, e.g prior to ignition.

If those aspects do not matter to you, then you can proceed, I won't stop you.

Some examples of where you may use the Dependency macro over DI:

• Utility functions
• Roact components

It is possible to bypass circular dependency errors using the Dependency macro, but this is not recommended and is widely considered an anti-pattern.

const myDependency = Dependency<MyDependency>();