正确使用依赖注入容器[关闭]

Question

So dependency injection then. I understand the concepts (I think!) and the use of containers. What I am failing to understand is the best way to make your DI container available everywhere.

If you have a DB class, do you inject the container into the constructor? So that you can call the DI container methods to create the dependant objects?

Do you do the same for your config class, your mailer class, your logger class and so forth? How do you make your DI container available everywhere?

Help appreciated!

Answer 1

My understanding is that you don't make it available everywhere. You register all of the objects and their dependencies, and then when you construct the object, the IoC container supplies all of its dependencies (and 2nd-, 3rd-, nth- level dependencies).

So foo needs bar, bar needs baz and qux, and qux needs quux. Foo only needs bar injected, the IoC will take care of the details of supplying bar with its dependencies, and so on.

If foo needs to make more bars later, then it has a dependency on a bar factory, which the IoC can also supply.