Data class smell

Revision as of 00:32, 21 October 2010

The data class smell is present where a class has only fields, getters, setters and nothing else. It lacks the behaviours that make it a proper, stand-alone class (and consequently, the instantiated object).

Validity

What exactly is wrong with data classes? Data classes always seemed useful and necessary to me - for example, geometric constructs such as points and vectors (Have you tried types ? Are you using the right language ? (Let's move this to the discussion page, chaps --Lukas Korsika 00:32, 21 October 2010 (UTC) )). Data classes can definitely be misused, but I don't think this smell should be considered an automatic refactoring job.

Refactoring techniques

• Encapsulate Field - if there are public fields
• Encapsulate Collection - if there is collections in the class. This is to ensure unmodifiable, read only collections is returned
• Remove Setting Method - for fields whose values should not be changed
• Move Method or Extract Method - move method or extract method to move the behavior from the clients (that use the accessors of the data class) to data class

See also

• Eliminate irrelevant classes
• Keep related data and behavior in one place
• Code smells
• Refactoring