protected member

[m_schellens]

With my compiler (g++ 3.4) and the following input
I get:

g++ test.cpp

test.cpp: In constructor `TrinaryExpr::TrinaryExpr()':
test.cpp:4: error: `ProgNode*ProgNode::down' is protected
test.cpp:17: error: within this context

Is this a compiler bug or what am I missing?
Thanks,
marc



class ProgNode
{
protected:
ProgNode* down;
ProgNode* right;

public:
ProgNode();
};

class TrinaryExpr: public ProgNode
{
public:
TrinaryExpr(): ProgNode()
{
down = new ProgNode();
down->down = 0;
}
};


int main( int argc, char* argv[])
{
return 0;
}

 

[lilburne]

With my compiler (g++ 3.4) and the following input
I get:



test.cpp: In constructor `TrinaryExpr::TrinaryExpr()':
test.cpp:4: error: `ProgNode*ProgNode::down' is protected
test.cpp:17: error: within this context

Is this a compiler bug or what am I missing?

Deriving from a base class only gives you the right to access the
protected members of the derived class in your objects of your own class.

Consider the following classes:

class A {
protected:
int a;
};

class B : public A {
};

class C : public A {
};

class C should not be able to access the 'a' with class B simply because
they both derive from the same base.

 

[m_schellens]

Ok, thanks,
marc