Add new model or extend existing one?

Hi I have a model Workout and model Set.

Workout has_many sets, set belongs_to workout.

Set has certain properties, like number of repetitions for left hand, for right hand, total repetitions etc.

Now I'm in front of a dilemma how to create additional/different kind of sets with different properties (say set for time, set that goal is to reach certain number of repetitions etc.)

Should I extend set model and change form via javascript based on some choice (it would be easier with counting statistics out of sets but IMHO it would make validation more 开发者_如何学JAVAcomplicated) or shall I create new kind of sets?

Ideas/tips ?

Thank you

Petr

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I'd create a new model but If they're similar enough I'd use Single Table Inheritance and simply inherit say the statistics methods from Set.