Re: Multi-level inheritance and accessing base protected member variables

From:
Sumit Rajan <sumit.rajan@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Thu, 28 Jun 2007 14:39:35 +0530
Message-ID:
<5ehc6fF38md29U2@mid.individual.net>
Hari wrote:

Joseph Paterson je napisao:

Hi all,

I'm having some trouble with the following code (simplified to show
the problem)

class Counter
{
    protected:
        int m_counter;
}

template <class K, class V>
class IMap : public Counter
{

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From: Hari <pasalic.zaharije@gmail.com>
Newsgroups: comp.lang.c++
Subject: Re: Multi-level inheritance and accessing base protected member variables
Date: Thu, 28 Jun 2007 01:27:16 -0700
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Joseph Paterson je napisao:

Hi all,

I'm having some trouble with the following code (simplified to show
the problem)

class Counter
{
    protected:
        int m_counter;
}

template <class K, class V>
class IMap : public Counter
{
// Virtual function declarations
}

template <class K, class V>
class HashMap : public IMap<K, V>
{
// Implementation of the virtual functions declared in IMap
}

Now when I'm implementing the functions in the HashMap class, I can't
seem to access the m_counter member variable by just using m_counter
(I get an undeclared reference from GCC), but when I use this-

m_counter, then it works fine.

Could anybody help me out with this one?

Thanks,

Joseph Paterson.


If you exclude some errors (like missing ; at end of class or using
class instead of typename) I do not
see what is wrong, here is code that compiles without errors (on MINGW
and VC8):

class Counter
{
    protected:
        int m_counter;

};

template <typename K, typename V>
class IMap : public Counter
{
public:
    IMap() {}

    virtual void foo() = 0;

};

template <typename K, typename V>
class HashMap : public IMap<K, V>
{
public:
    HashMap() {}

    void foo() {
        m_counter = 10;

this->m_counter = 10;

See:
http://www.parashift.com/c++-faq-lite/templates.html#faq-35.19

     }

} ;

int main()
{
HashMap<int, int> a;
    a.foo();
}

P.S.
    You can always test code on multiple compilers at http://dinkumware.com/exam/
..

Best,
Pasalic Zaharije


Regards,
Sumit.

--
Sumit Rajan <sumit.rajan@gmail.com>

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