overloading functions with base class smart pointers

Question

I have 3 classes: the first a pure virtual base class base with derived classes derived1, derived2...

the second foo holds a smart ptr to a base class

the third holds a smart ptr to foo and has an overloaded member function which I want to depend on the derived class the ptr in foo points to.

Here is the working code

#include<iostream>
#include<boost/shared_ptr.hpp>

using namespace std;

class base{
public:
    base(){}
    ~base(){}
    virtual void FuncDer()=0;
};

class derived1 : public base{
    derived1(){}
    virtual void FuncDer(){
    cout<<"derived function1!"<<endl;
    }
};

class derived2 : public base{
    derived2(){}
    virtual void FuncDer(){
        cout<<"derived function2!"<<endl;
}
};

class foo {
public:
   foo();
    ~foo();
    boost::shared_ptr<base> get_base_ptr(){
        return base_obj;
    }
private:
    boost::shared_ptr<base> base_obj;
};

class bar {
public:
    bar();
    ~bar();
    void callfunc(){
    func(foo_ptr->get_base_ptr());
    }
private:
    boost::shared_ptr<foo> foo_ptr;
    void func(boost::shared_ptr<derived1>);
    void func(boost::shared_ptr<derived2>);
};


int main()
{
    cout<<"test"<<endl;

    return 0;
}

This however seems to fail with the error no matching member function. So my question is firstly is there something obviously wrong with this approach and secondly is there a more efficient / object oriented design approach which better deals with this type of problem.

Is it possible to have additional virtual function in derived classes that takes object of class bar as parameter, and to change bar::func functions into public? — Dialecticus
Sorry for the delay I havent had the chance to look at this until now. I have now posted working code that reproduces my error. — emza0114

dornhege dornhege · Accepted Answer · 2013-09-12T11:27:52

In principle this is the right way of doing it: Call the function on the base and polymorphism will do the right thing.

However, your code won't compile: The func definitions in bar aren't valid (at least I'm not sure what you intended them for - what are they supposed to implement?) and the func call in callfunc dereferences the pointer twice.

If you need concrete fixes, give the exact error.

overloading functions with base class smart pointers

1 Answers