Now, we are well aware that DI is meant to provide the dependencies to components through either a constructor, the setter method, or properties to make them separate from dependency services. The conventional understanding is that this can only be possible by using IoC containers. However, this is not true for all cases.

Ideally, IoC containers should be used for configuring and resolving a comparatively large set of dependencies in complex applications. If you are dealing with a simple application that has just a few components and dependencies, it is sensible not to use containers. Instead, you can wire dependencies manually. 

Also, in the case of any legacy system where the integration of a container is difficult, you can opt for supplying dependencies manually. You can implement various patterns, such as the factory method, service locator, strategy, or template method patterns, to manage the dependencies.