I have two classes of a one interface:

interface TimeUtils { ... }
class TimeUtilsImpl : TimeUtils { ... }
class TimeUtilsSimulation : TimeUtils { ... }

TimeUtils binding is in the module A:

bind(TimeUtils::class.java).to(TimeUtilsImpl::class.java).`in`(Singleton)

TimeUtilsSimulation binding is in the module B:

bind(TimeUtils::class.java).to(TimeUtilsSimulation::class.java).`in`(Singleton)

and these modules A and B are used in different binaries.

I injected TimeUtils in a common code like:

class SomeClass @Inject constructor(
  private val timeUtils: TimeUtils
)

And now I have a problem that when I have a request to start simulation I need to set an initial time in the TimeUtilsSimulation object. I can do it like this:

class RequestHandler @Inject constructor(
  private val someObject: SomeClass
)
onRequest(simulationStartTime: LocalDateTime) {
   if (timeUtils instanceof TimeUtilsSimulation) {
       // Set start time in a singleton timeUtils object
       (timeUtils as TimeUtilsSimulation).setStartTime(simulationStartTime)
   }
   someObject.run()
}

but it looks ugly. Can you suggest something to solve this bad design?

CodePudding user response：

Maybe add setStartTime to TimeUtils interface and do not implement it in TimeUtilsImpl? It all depends on the context. For unit testing for example I think your solution would be fine. But for other, "normal" business logic is seems fishy. It's almost like the interface does not really abstract the concept properly

CodePudding user response：

I don't know Kotlin, but pure OOP speaking, the best would be to define a TimeUtilsWrapper interface that extends TimeUtils and adds setStartTime(...) method. Then you would have 2 classes implementing this interface:

• 1 that embeds a TimeUtils object with empty setStartTime() that delegates all other methods to the embedded object,
• second that embeds a TimeUtilsSimulation and delegates all methods to it, including setStartTime() calls to it.

Then SomeClass method should have a property of type TimeUtilsWrapper instead of TimeUtils and onRequest(...) should just always call TimeUtilsWrapper's setStartTime(...).