[From ClassicOoAntiPatterns]

Absence of data encapsulation. The data members may be public (or might as well be because they are exposed to the world through getters and setters), or the objects may hold references to each other. In any case the objects end up doing more tweaking of the other objects' data than of their own, with ensuing confusion about who did what to whom when.

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See also EncapsulationIsaWasteOfTime