Code Smell 40 - DTOs
Data Transfer Objects (DTOs) are widely used, and they 'solve' real problems, do they?
Information Hiding Violation
Transfer anemic data on arrays.
Use real business objects.
If we want to transfer partial objects: use proxies or null objects to break the reference graph.
We can use the same anemic object detectors.
We can check for anemic classes with no business object behavior (removing serializes, constructors, mutators etc).
DTOs are a tool and an established practice in some languages. We should use them with care and responsibility.
If we need to disassemble our objects in order to send them away from our realms, we need to be extremely cautioned. Since dismembered objects have no integrity considerations.
His author warns us about its actual abuse.
The best smells are something that's easy to spot and most of time lead you to really interesting problems. Data classes (classes with all data and no behavior) are good examples of this. You look at them and ask yourself what behavior should be in this class.
This article is part of the CodeSmell Series.