Should a class validate itself or create another c

Question

Let's say I have a class like:

class NavigationData
{
  float roll;
  float pitch;
  double latitude;
  double longitude;
}

and if I want to create a method:

const bool validate() const;

which basically validates whether the 4 fields contain valid values.

Should validate() be part of NavigationData class, or should I create something like a NavigationDataValidator, that contains a validate(const NavigationData&) method.

I'm just giving a simple example, obviously my real class is a lot more complicated than this. I'm looking for good OO principles.

Put it another way: given a method, how do we know if it should belong to the class, or should belong to a separate class?

Answer 1

I would say it depends. If the class's data is validatable in isolation I would put the method in the class, but if the validation requires a context then I would create a validator class based on some interface.

Answer 2

I'd say have it validate itself as long as the valid values don't depend on what other classes use NavigationData.

Basically, as long as latitude and pitch has to always be between +/- 90 degrees, and longitude and roll always be between +/- 180 degrees, keep the validator in the class.

(By the way, what about heading?)