How to perform specific tasks for each subclass in the base class constructor

manpreet Best Answer 3 years ago

I have a base class. For example:

class CData{
public:
    CData(const std::string &_filename)
    {
        m_filename = _filename;
        // LodaData(); // wrong
    }

    virtual void LoadData() = 0;
private:
    std::string m_filename;
};

And, a subclass:

class COtherData: public CData{
public:
    COtherData(const std::string &_filename): CData(_filename) {}

    virtual void LoadData() {
    // some code to load data
    ...
    }
};

I want to know how to perform some tasks in base class for subclasses.

manpreet 3 years ago

Create different constructors in the base class, then in the subclass call the appropriate constructor. Or use default arguments that change appropriately.

class A  
{  
   A(int a = 0) 
   {
        if(a == 0) // first case
        else // second case
   }

};

class B : public A 
{
    B() : A(0) {} // First case
    --- or --- 
    B() : A(1) {} // Second case
}