Overiding a virtual function of multiple inheritance base class

[Ronnie]

Please look at the code below,

class BaseCol
{
public:
virtual void a() { cout << "BaseCol::a " << endl; }
virtual void b() { cout << "BaseCol::b " << endl; }
};

class ChildCol1 : public BaseCol
{
public:
virtual void a() { cout << "ChildCol1: :a" << endl; }
virtual void b() { cout << "ChildCol1: :b" << endl; }
};

class ChildCol2 : public BaseCol
{
public:
virtual void a() { cout << "ChildCol2: :a" << endl; }
virtual void b() { cout << "ChildCol2: :b" << endl; }
};

class Row : public ChildCol1, public ChildCol2
{
public:
// i want to overide the b function of ChildCol1 only !!
void b() { cout << "Row1::b" << endl; }
};

Now,
In Row class, How do i tell the compiler that i want to overide for
example only the b() function of ChildCol1 base class (and leave the
implementation for this function from ChildCol2) ?

TNX,
Ronnie

[Gianni Mariani]

Ronnie wrote:

Please look at the code below,

class BaseCol
{
public:
virtual void a() { cout << "BaseCol::a " << endl; }
virtual void b() { cout << "BaseCol::b " << endl; }
};

class ChildCol1 : public BaseCol
{
public:
virtual void a() { cout << "ChildCol1: :a" << endl; }
virtual void b() { cout << "ChildCol1: :b" << endl; }
};

class ChildCol2 : public BaseCol
{
public:
virtual void a() { cout << "ChildCol2: :a" << endl; }
virtual void b() { cout << "ChildCol2: :b" << endl; }
};

class Row : public ChildCol1, public ChildCol2
{
public:
// i want to overide the b function of ChildCol1 only !!
void b() { cout << "Row1::b" << endl; }
};

Now,
In Row class, How do i tell the compiler that i want to overide for
example only the b() function of ChildCol1 base class (and leave the
implementation for this function from ChildCol2) ?

class Row : public ChildCol1, public ChildCol2
{
using ChildCol2::b();
};

[Gianni Mariani]

Gianni Mariani wrote:

Ronnie wrote:

Please look at the code below,

class BaseCol
{
public:
virtual void a() { cout << "BaseCol::a " << endl; }
virtual void b() { cout << "BaseCol::b " << endl; }
};

class ChildCol1 : public BaseCol
{
public:
virtual void a() { cout << "ChildCol1: :a" << endl; }
virtual void b() { cout << "ChildCol1: :b" << endl; }
};

class ChildCol2 : public BaseCol
{
public:
virtual void a() { cout << "ChildCol2: :a" << endl; }
virtual void b() { cout << "ChildCol2: :b" << endl; }
};

class Row : public ChildCol1, public ChildCol2
{
public:
// i want to overide the b function of ChildCol1 only !!
void b() { cout << "Row1::b" << endl; } };

Now,
In Row class, How do i tell the compiler that i want to overide for
example only the b() function of ChildCol1 base class (and leave the
implementation for this function from ChildCol2) ?

class Row : public ChildCol1, public ChildCol2
{
using ChildCol2::b();
};

WRONG ...

It's "using ChildCol2::b" (note the missing '()' ) and this does not do
what I think you want it to do.

You can't really do what you want it to do. If you implement a function
virtual b() in Row - it overrides all virtual "b()" functions.

The way I've done this is:
class BaseCol
{
public:
virtual void a() { cout << "BaseCol::a " << endl; }
virtual void b() { cout << "BaseCol::b " << endl; }
};

class ChildCol1 : public BaseCol
{
public:
virtual void a() { cout << "ChildCol1: :a" << endl; }
virtual void b() { b1(); }
virtual void b1() { cout << "ChildCol1: :b1" << endl; }
};

class ChildCol2 : public BaseCol
{
public:
virtual void a() { cout << "ChildCol2: :a" << endl; }
virtual void b() { b2(); }
virtual void b2() { cout << "ChildCol1: :b2" << endl; }

};

class Row : public ChildCol1, public ChildCol2
{
public:
// i want to overide the b function of ChildCol1 only !!
void b1() { cout << "Row1::b" << endl; }
};

In other words - you need to expose a different b.

[EventHelix.com]

The function b() will override *both* b functions. Within the code
for the overriden b you could invoke ChildCol::b and ChildCol2::b.

Sandeep
--
http://www.EventHelix.com/EventStudio
EventStudio 2.0 - Generate Sequence Diagrams and Use Case Diagrams in PDF

[Ronnie]

ev********@hotm ail.com (EventHelix.com ) wrote in message news:<56******* *************** ****@posting.go ogle.com>...

The function b() will override *both* b functions. Within the code
for the overriden b you could invoke ChildCol::b and ChildCol2::b.

Sandeep

So if i write "using" how does this help me overide b function of any
of the multiple base class...please answer with code of overiden
function (one for each base class)

TNX,
Ronnie