Public member variables acceptable?

I made it a habit to always, without any exception, declare my member
variables private. However, there are some situations where it seems
that it's ok to make an exception. For example in a Point class:

class Point
{
public:
     Point();
     Point(int inX, int inY);

     int x;
     int y;
};

Would this be bad design?

On what principles would the decision to declare a member public be
based?


Kind regards,
Francis


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