As it happens, it’s just an example to illustrate specifically the “extract to method” issues the author had.
Of course, in a real world scenario we want to limit mutating state, so it’s likely this method would return a Commission list, which would then be used by a Use Case class which persists it.
I’m fairly sure the advice about limiting mutating state is also in the book, though.
At the same time, you’re likely going to have a void somewhere, because some use cases are only about mutatimg something (e.g. changing something in the database).
Why is it a
voidmethod? This only tells me that some state is mutated somewhere, but the effect is neither visible nor documented.I would expect a function called “calculate” to just return a number and not have any side effects.
You’re nitpicking.
As it happens, it’s just an example to illustrate specifically the “extract to method” issues the author had.
Of course, in a real world scenario we want to limit mutating state, so it’s likely this method would return a
Commissionlist, which would then be used by a Use Case class which persists it.I’m fairly sure the advice about limiting mutating state is also in the book, though.
At the same time, you’re likely going to have a void somewhere, because some use cases are only about mutatimg something (e.g. changing something in the database).