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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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;

}

} ;

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