Question

Though DI in interface driven…I am still not clear as to what exactly differentiates this from basic overloading concept. Any C# examples would be helpful.

EDIT : I read here the reason for my question
that StreamReader can be seen as example of IoC/DI…how is this different totally from overloading? Or is it just semblance to DI and not entirely DI?

Answer 1

They’re completely different concepts.

Overloading: providing multiples methods with the same name (or constructors) that differ by the number and/or type of parameters.

Dependency Injection: giving components all the services they need to work with (e.g. authenticators, database connections etc) rather than letting them construct these dependencies themselves. DI encourages a clean separation between interfaces and implementation, and makes unit testing much easier (as you can mock/fake dependencies).

EDIT: I don’t think I’d usually use StreamReader as a good example of dependency injection – in particular, it can create its own streams for you if you only specify a filename. Arguably the overloads with a Stream parameter are effectively allowing the stream dependency to be injected, but it’s not what I’d normally consider as DI. The constructor is certainly an example of overloading – but the two are really unrelated.

Normally I’d think of DI in terms of services – things like authenticators, or potentially the next service in a chain (where a request goes through multiple stages, for example).