There is this famous example, that you can find in almost every OOP-related book:
Let's say that account is an object, and you have:
For some time now, I've had issues with this example.
Is it really a responsibility of the account object to transfer money to another account?
Is it not one of the responsibilities of the Bank object? It just feels weird that an account knows how to do the proper stuff about the complicated transferring use case.
The topic of DCI is really popular recently, which is cool, as it's a very fresh approach to object oriented architectures. The .transfer example in DCI is usually implemented as injecting the SourceAccount and TargetAccount roles to the basic account objects. We change the implementation, but the effect is the same - the account object has the knowledge about the transfer stuff.
Wouldn't it be better if we have this as a responsibility of the Bank object? It could work as a use case or as a role, but both fit better in the bank, in my opinion.
What do you think?
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