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c++this-pointer

Is using *this a good idea?

I'm not sure if 

return *this

is the only way we could return an instance of a class who called a member function? The reason why I asked is because our instructor told us to avoid using pointers if necessary and I'm wondering if this is a case where the only necessary way to do it is by returning the this pointer.

I'm working with a fraction class that holds private data members numerator and denominator. The member function I'm talking about is used to add two fractions for example:

Fraction C = A.plus(B);

plus member function is defined as this:

Fraction& plus( const Fraction frac )

The instructor wants us to do C = A += B , so I guess that's why.

Solution

  • Get a new instructor. It looks as if the declaration of plus() is completely wrong.

    • it probably should return a value rather than a reference
    • if it must return a reference, it should return a const reference
    • it should definitely take a const reference as a parameter

    That is for likely sensible implementations of a member plus() function. Of course, it should probably be a friend.