Re: Class inheritance 101

Alex Blekhman <xfkt@oohay.moc>
Wed, 30 May 2007 11:51:02 +0300
Anders Eriksson wrote:


I have a class, yClass, that I need to add a couple of member variables to.
So I thought I knew how to do this but it turns out I don't ;-)

class yClass
     /// Construct an yClass instance

    /// Construct an yClass instance initializing from a given object
    yClass(yClass& yObj);

    /// Default destructor
    virtual ~yClass();

class mClass : public yClass
  int m_x;
  int m_y;
  zClass *m_pzObj;

How do I write the constructor and deconstructor for mClass so it also
calls yClass constructor and deconstructor.

It's simple:

class mClass : public yClass
   mClass() {}
   mClass(const mClass& other) : yClass(other)
     m_x = other.m_x;
     m_y = other.m_y;
     m_pzObj = ...;

   ~mClass() { /* release m_pzObj */ }

   int m_x;
   int m_y;
   zClass *m_pzObj;

You don't need to write anything for default constructor
`mClass::mClass()'. Base class constructor will be called
automatically. The same is true for destructor.


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