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Comment by surgical_fire | Hacker News Reader

> That for example is just not true. You add a new parameter to inject and it breaks the injection points?

Perhaps you never worked in a sufficiently large codebase?

It is very annoying when you need to add a dependency and suddenly you have to touch 50+ injection points because that thing is widely used. Been there, done that, and by God I wished I had Dagger or Spring or anything really to lend me a hand.

DI frameworks are a tool like any other. When properly used in the correct context they can be helpful.

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This is the only reason why DI frameworks exist. However, this issue can be largely avoided by working with configuration objects (parameter objects [0]) from the start, that get passed around. Then you only need to apply the change in a small number of parameter-object classes, if not just a single one.

[0] https://wiki.c2.com/?ParameterObject

Eh, having built a whole codebase around these configuration objects I really regret not going for more traditional DI IoC container. It's thousands over thousands of additional parameters passed all over the place when creating objects just for the sake of saving five minutes of explanation to newcomers.

"It is very annoying when you need to add a dependency and suddenly you have to touch 50+ injection points because that thing is widely used"

You don't have to update the injection points, because the injection points don't know the concrete details of what's being injected. That's literally the whole point of dependency injection.

Edited to add: Say you have a class A, and this is a dependency of classes B, C, etc. Using dependency injection, classes B and C are passed instances of A, they don't construct it themselves. So if you add a dependency to A, you have to change the place that constructs A, of course, but you don't have to change B and C, because they have nothing to do with the construction of A.

I think you're being downvoted because you're agreeing with the post you're quoting, but arguing as if they're wrong: the example in question was there to show how DI can be useful, so there's nothing to argue against.

Ya very confused by this. Either the change is to the constructor of the object being injected, in which case there is no difference either way, or the change is to the constructor receiving the injection, in which case there’s no difference either way.

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