Question

I am trying to convert from a base class to a derived class.
I have the following constructor, however, the compiler complains with:

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

constructor:

derivedObject(const baseObject &base, const std::string &extra1)
{
    baseparameter1 = base.baseparameter1;
    baseparameter2 = base.baseparameter2;
    extraparameter1 = extra1;
}

Any advice?

Answer 1

Every constructor begins by initializing all base classes and direct members, before you get to the {. Instead of using assignments in the body, use a member initializer list:

derivedObject(const baseObject &base, const std::string &extra1)
    : baseObject(base),        // Calls the baseObject copy constructor
      extraParameter1(extra1)  // Initialize the direct member
{
}

This is better style and also avoids problems like the one you ran into.