I have objects which implement the interface BroadcastInterface, which represents a message that is to be broadcast to all users of a particular group. It has a setter and getter method for the Subject and Body properties, and an addRecipientRole() method, which takes a given role and finds the contact token (e.g., an email address) for each user in the role and stores it. It then has a getContactTokens() method.

BroadcastInterface objects are passed to an object that implements BroadcasterInterface. These objects are responsible for broadcasting a passed BroadcastInterface object. For example, an EmailBroadcaster implementation of the BroadcasterInterface will take EmailBroadcast objects and use the mailer services to email them out.

Now, depending on what BroadcasterInterface implementation is used to broadcast, a different implementation of BroadcastInterface is used by client code. The Single Responsibility Principle seems to suggest that I should have a separate BroadcastFactory object, for creating BroadcastInterface objects, depending on what BroadcasterInterface implementation is used, as creating the BroadcastInterface object is a different responsibility to broadcasting them.

But the class used for creating BroadcastInterface objects depends on what implementation of BroadcasterInterface is used to broadcast them. I think, because the knowledge of what method is used to send the broadcasts should only be configured once, the BroadcasterInterface object should be responsible for providing new BroadcastInterface objects.

Does the responsibility of “creating and broadcasting objects that implement the BroadcastInterface interface” violate the Single Responsibility Principle?

(Because the contact token for sending the broadcast out to the users will differ depending on the way it is broadcasted, I need different broadcast classes—though client code will not be able to tell the difference.)