Question

hei i have a c++03 class with a simple constructor that take an integer. And a derived class with serialization methods that should take a filename as a constructor, load the integer from it, and then call the first constructor.

class A {
public:
    A(int foo);
}

and a derived class:

class XmlableA : public A {
public:
    XmlableA(int foo);

    XmlableA(string xmlfilename) {
        //load foo from xml
        // call A::A(foo)
    }
}

i tried some different solution but every time i get

no matching function for call to ‘A::A()’

Answer 1

Almost all answers are same, so I would suggest a different solution, which I would prefer personally.

Define a static member function Create as:

class XmlableA : public A {
public:
    XmlableA(int foo);

    //static member function
    static XmlableA Create(string const & xmlfilename) 
    {
        //load foo from xml
         int foo = /*load from file*/;
         return XmlableA(foo);
    }
};

Usage:

XmlableA xmlable = XmlableA::Create(xmlFile);