Re: polymorphic use problem

From:

Joe Greer <jgreer@doubletake.com>

Newsgroups:

comp.lang.c++

Date:

Thu, 10 Jul 2008 16:55:22 +0000 (UTC)

Message-ID:

<Xns9AD783759C823jgreerdoubletakecom@85.214.90.236>

Angus <anguscomber@gmail.com> wrote in news:67a176cb-5052-45d3-9dc4-
6bc47f3fff1f@27g2000hsf.googlegroups.com:

If I have these classes:

class TBase
{
public:
    virtual int Execute(Server* srv) = 0;
    virtual ~TFunction() {}
};

class Derived : public TBase
{
public:
    Derived(const std::string& strA, int ia1)
    : m_strA(strA), m_ia1(ia1){
    }

    virtual int Execute(TServer srv)
    {
        return SomeFunction(srv, m_strA, m_ia1);
    }
    ~TRegister() { }
private:
    std::string m_strA;
    int m_ia1;
};

I want to call the Execute function on a Derived object. How can I
call it?

I have to point out that as written this won't compile because int
Execute(Server *) isn't implemented any where (unless TServer is a
typedef for a Server *). However, assuming you meant them to be the
same...

If you had:

void f(TBase & t)
{
   Server s;
   t.Execute(&s);
}
..
..
..

int main()
{
   Derived d("blah", 4);

   f(d);
}

Is that what you have in mind? Or was it more like:

void f(TBase * t)
{
   Server s;
   t->Execute(&s);
}

int main()
{
   Derived d("blah", 3);
   TBase * pT = &d;

   f(pT);
}

Either way works. Polymorphism requires a pointer or reference at some
point or you aren't really polymorphic.

joe