Is the single responsibility principle directly related to class' dependencies?

Question

If a class is dependent through interfaces on more than one other class is that a violation of SRP, or is it only a violation if both interfaces are expected to change, or is this the wrong line of thought altogether?

Answer 1

The SRP is in principle entirely orthogonal to what and how many dependencies the class might have.

A class can have a single responsibility, but if that responsibility is complex to carry out it may have many dependencies on "sub-contractors" that take care of the menial work. In essence, your single responsibility is "coordinate these people so that X happens".

Answer 2

Not necessarily. A class could still have one responsibility but have multiple dependencies. Having multiple dependencies is often a sign that a class is doing to much, but it's not proof of that.

Answer 3

If the class just call methods on those dependent interfaces, that wouldn't' be a violation of SRP since it's orchestrating a process calling different methods on different components, that would be the responsability.

It's hard to provide an exact answer without a specific context but in short: having dependencies with multiple interfaces it's not a violation of SRP per se.