It's 2019 and DI is a well-known and established technique on all major platforms and languages. So why can't we still have a clear answer to the questions like 'is DI/IoC container a mandatory thing to apply DI?' or 'what is a true way to implement DI in language/platform X?' or ‘is it even a good/useful thing?’. Let's find those answers together and refresh our memory on the initial goals and targets of DI and its surrounding design patterns.