Asking about ports and adapters about ploeh.github.com HOT 7 CLOSED

Does this answer your question? http://stackoverflow.com/a/9503612/126014

from ploeh.github.com.

I don't think so.

As far as I know, dependency inversion is, because doing some task and creating instances of the dependencies in the same class would violate the single responsibility principle. So because of this we have to inject the dependencies and create classes (one or more DI container) with the task of instantiating classes...

Maybe I just misunderstood one of your graphs. The arrow from the data access library to the domain library means to me, that the domain library will be injected with dependency injection to the data access library. This is unusual to me. If I want to save something in my database I want to ask the database to save it for me, not for example trigger a persist event and listen to those events from the database... But this invertion of yours says that to me :S I am confused...

from ploeh.github.com.

The arrows describe references, so in this case it means that the Domain Library has references to neither User Interface Library nor Data Access Library. Instead, the Data Access Library has a references to the Domain Library.

At run-time, the objects from the Domain Library will be injected with objects from the Data Access Library, so that they can invoke their services.

This is unusual to me. If I want to save something in my database I want to ask the database to save it for me, not for example trigger a persist event and listen to those events from the database... But this invertion of yours says that to me

Well, there's a reason it's called Inversion of Control :)

Have you read my book?

from ploeh.github.com.

Not yet, I don't have time to read books. :S I just found your blogpost...
Are you aware, that ppl uploaded your book to several sites?

from ploeh.github.com.

At run-time, the objects from the Domain Library will be injected with objects from the Data Access > Library, so that they can invoke their services.

Hmm so the domain library is aware of the data access library objects (maybe just interfaces). It's okay then, I just misunderstood. In my approach the classes in the layers/modules do not know of the existence of each other, and a DI container instantiates and injects them into each other whenever it is necessary...

from ploeh.github.com.

Thanks for the heads-up!

from ploeh.github.com.

You're welcome!

from ploeh.github.com.