Alternatives

Although there are many, many other dependency injection libraries, I found that I was still left looking for more lightweight/minimal solutions to this problem. My thoughts on some of the popular alternatives I have used in the past:

• dependency-injector

  This library is probably the most mature out of all the alternatives. Its main driving principal is that “Explicit is better than implicit”, in that you need to specify explicitly how to assemble/ inject the dependencies. flexdi is still explicit in the sense that dependencies are directly referenced from their type annotations, and by leveraging them we can avoid a lot of the more verbose setup required in DeclarativeContainer structures.
• fastapi

  This web framework provides an excellent way to perform dependency injection, but it does not provide a way to perform dependency injection outside the context of web request. When configuring the injection, you must also provide default values to arguments, which ties application code to the web framework, making it more difficult to re-use code in other contexts. Additionally, it does not provide rich support for lifetime/singleton scoped dependencies, making the setup of some dependencies increasingly awkward.
• pinject

  This library allows you to perform DI with minimal setup, but its major downfall is that it relies on the names of arguments to perform injection. If the name of the argument does not match the name of the class, then you are forced to bind it explicitly. If there are multiple objects that specify a dependency of a particular type, but use different names, then you need to bind them all individually as well. And sadly, this project has now been archived and is read-only.