Introduction of a Dependency Injection Framework

[R4md4c]

Current Implementation

Right now, The code uses object Singletons and static methods to access shared data and execute code e.g. [1], [2] and in many more files.

This would make testing so hard as it will make the experience for developers and contributors unpleasant as they would spend more time in writing the mock code rather than testing their actual work. e.g. [3]

Suggested Enhancement

Introduction of a DI framework that will make writing a testable, maintainable and extensible code achievable. The selection of which framework to use is up to the maintainers.

Expected Benefits

These are the points on top of my head, I might be for sure missing some.

• Embracing constructor injected objects rather than the current approach of using object singletons, as using Singletons is considered as anti-pattern.
• Reducing the memory footprint of the application since the DI framework will take care of scoping of the objects, right now everything is declared object and once accessed it will be kept in memory even though it may not be needed anymore after it has served its purpose.
• Instrumentation tests would be easier to write since the created test DI Graph will be responsible to provide the dependencies across all the application layers, right now it is impossible to provide a mock network or a Database for example
• Increasing the test coverage point in the README would be easier to achieve as objects will be able to get instantiated through ctor injection hence providing fakes/mocks would be easier.

[MrIceman]

You don't even need a DI library, most of the time Dagger2 or Koin produce more Boilerplate code than a simple singleton Factory would do

[kedar1607]

What do you guys think about using Android Dagger instead of standard dagger. This is optimized especially for android and is much less verbose than standard dagger. For example you don't need to manage subcomponents yourself, @ContributesAndroidInjector does all that magic for you.

[marcmuschko]

Hi @R4md4c,

thank you for this suggestion! We are currently evaluating if and when to include this as it would require quite a bit of effort on our side. I will leave the issue open and keep you posted!

Best, Marc

[duke2906]

It may be worth to have a look on Kodein https://kodein.org/di/

[timo-drick]

Please do not introduce more complexity as necessary. It is much more difficult to understand the code when Dagger or similar frameworks are used. And it is also possible to do testing without this frameworks. Btw. in my opinion the testing argument is very weak to justify that the code will be obfuscated. Especially for this porject it is very important to keep every thing as simple as possible.

[Eklow02]

If you want to introduce DI, I would suggest that you use koin (https://github.com/InsertKoinIO/koin). It doesn't create so much code like dagger and is easy to understand

[svenjacobs]

@timo-drick I don't see how the dependency injection pattern introduces "unnecessary" complexity? Actually you don't need a framework like Dagger 2 for implementation. The basic pattern is very simple and can be implemented "by hand". I see many benefits of this pattern like modularity, reusability and testability for example.

[MrIceman]

If you're such a fan ob singletons then I guess singleton factories would make it too, at the end this is what dagger2 generates. But dependency injection and testing is necessary for quality assurance, especially in a project like this. The DI framework at the end is just a detail, but you need to get rid of the singleton calls or you won't have testable code at all

[AlexanderEggers]

I am not part of this project, but I am happy to help with this part. I actually wrote my own annotation processor that simplifies the overall usage of Dagger2 for Android: https://github.com/Mordag/archknife Let me know if I can get start with switching to Dagger or my own lib.

[yanniks]

Google recently announced Dagger Hilt which should be the way to go I guess: https://developer.android.com/training/dependency-injection/hilt-android

I have implemented it in one of our projects already, with very high satisfaction.

[MrIceman]

there are many frameworks, just build your own factories imo. It's not that difficult

[MovGP0]

there are many frameworks, just build your own factories

Even when implementing a DI framework is simple, I see no reason to reinvent the wheel. Using an existing DI framework is best practice.

[d4rken]

We've now introduced Dagger2 as DI framework in #1069 and will steadily increase DI integration in the project.

We picked dagger-android over hilt because there are only hilt -alpha releases available.