Guidelines to deal with class dependencies

I have a doubt on the best approach to handle a class dependency and I was hoping to have some feedback on the issue.

Let's assume I have a class to model the Earth's ionosphere

class EarthIonosphere {
    // Methods that implement physical models of the Earth's ionosphere
}

To do some computations within EarthIonosphere, I might have the need to know the value of the Earth's magnetic model. Therefore I have an independent class for this:

class EarthMagneticField {
    // Methods that implement physical models of the Earth's magnetosphere
}

EarthIonosphere might depend on EarthMagneticField (but not the other way round). By the way, EarthMagneticField might also be needed in other parts of the code. With this in mind I was wondering which is the best solution (in terms of re-usability and maintainability) to approach this dependency. The two options I was considering were:

• EarthIonosphere contains a private/public member of class EarthMagneticField, but I am concerned on duplication in case the same EarthMagneticField has to be used in other parts of the code.


• EarthIonosphere contains a std::shared_ptr that points to an object of class EarthMagneticField that has been instantiated using the new operator. This would allow me to use exactly the same object to compute the magnetic field in other parts of the code.

Do you think any of these is a viable solution in terms of "clean code"? otherwise, do you have any suggestion like some "interface" class or similar?

Many thanks!