Must Dependency Injection come at the expense of Encapsulation?

Question

If I understand correctly, the typical mechanism for Dependency Injection is to inject either through a class\' constructor or through a public property (member) of the clas

Answer 1

This exposes the dependency being injected and violates the OOP principle of encapsulation.

Well, frankly speaking, everything violates encapsulation. :) It's a kind of a tender principle that must be treated well.

So, what violates encapsulation?

Inheritance does.

"Because inheritance exposes a subclass to details of its parent's implementation, it's often said that 'inheritance breaks encapsulation'". (Gang of Four 1995:19)

Aspect-oriented programming does. For example, you register onMethodCall() callback and that gives you a great opportunity to inject code to the normal method evaluation, adding strange side-effects etc.

Friend declaration in C++ does.

Class extention in Ruby does. Just redefine a string method somewhere after a string class was fully defined.

Well, a lot of stuff does.

Encapsulation is a good and important principle. But not the only one.

switch (principle)
{
      case encapsulation:
           if (there_is_a_reason)
      break!
}