Interface implementation

[Galian]

Hi all. I have some questions about interface implementation, if
anybody can help me, I will be very thank.
So:

If i have some interface IA:

class IA
{
virtual void SomePureVirtFun c() = 0;
};

and some class B, that implemented that interface:

class B : public IA
{
virtual void SomePureVirtFun c() {};
};

Now I need in class C inherit from interface ITwoInOne, that inherited
from IA also.
Question: it is any method, inherit from interface ITwoInOne, and
don't implement interface IA, but using multiple inheritance - inherit
from class B, that already implemented that interface, and satisfy my
requirements?

Another words: can I write something like that:

class NewOne : public B
, public ITwoInOne
{
//Implementation only pure virtual functions
//, that not correspond to IA interface
}

P.S. sorry for confusion, and for my bad English.

[Victor Bazarov]

Galian wrote:

Hi all. I have some questions about interface implementation, if
anybody can help me, I will be very thank.
So:

If i have some interface IA:

class IA
{
virtual void SomePureVirtFun c() = 0;
};

and some class B, that implemented that interface:

class B : public IA
{
virtual void SomePureVirtFun c() {};
};

Now I need in class C inherit from interface ITwoInOne, that inherited
from IA also.
Question: it is any method, inherit from interface ITwoInOne, and
don't implement interface IA, but using multiple inheritance - inherit
from class B, that already implemented that interface, and satisfy my
requirements?

Yes, inherit from IA _virtually_ *everywhere*. I.e. make B inherit from
IA virtually and make ITwoInOne inherit virtually.

>
Another words: can I write something like that:

class NewOne : public B
, public ITwoInOne
{
//Implementation only pure virtual functions
//, that not correspond to IA interface
}

P.S. sorry for confusion, and for my bad English.

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[Galian]

Yes, inherit from IA _virtually_ *everywhere*. I.e. make B inherit from

IA virtually and make ITwoInOne inherit virtually.

So this is right way:

class B : public virtual IA
{

};

class NewOne : public virtual B
, public virtual ITwoInOne
{

};

Is this right?
If yes, than question: is order of classes for inheritance important?
I mean it is OK if I write first "public virtual ITwoInOne", and than
"public virtual B"?

[Victor Bazarov]

Galian wrote:

>Yes, inherit from IA _virtually_ *everywhere*. I.e. make B inherit
from IA virtually and make ITwoInOne inherit virtually.

So this is right way:

class B : public virtual IA
{

};

class NewOne : public virtual B
, public virtual ITwoInOne
{

};

Is this right?
If yes, than question: is order of classes for inheritance important?
I mean it is OK if I write first "public virtual ITwoInOne", and than
"public virtual B"?

I think that the order is not significant. Have you tried it? If you
have, and the success depended on the order, could you please share?
If you haven't tried, why?

V
--
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[Galian]

I have tried, and it don't work. "Cannot instantiate abstract class"
error. I don't now why. I tried different order, but it don't help.
Thank you Victor for the answers.

[Victor Bazarov]

Galian wrote:

I have tried, and it don't work. "Cannot instantiate abstract class"
error. I don't now why. I tried different order, but it don't help.

Sounds like FAQ 5.8 should help. Check it out. It also can be that
your compiler is not capable; we'll know as you check out the FAQ.

Thank you Victor for the answers.

You're most welcome.

V
--
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I do not respond to top-posted replies, please don't ask

[Galian]

Victor Bazarov :

Galian wrote:

I have tried, and it don't work. "Cannot instantiate abstract class"
error. I don't now why. I tried different order, but it don't help.

Sounds like FAQ 5.8 should help. Check it out. It also can be that
your compiler is not capable; we'll know as you check out the FAQ.

Thank you Victor for the answers.

You're most welcome.

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

Sorry Victor, but about what FAQ you talking? Where can I find it?

[red floyd]

Galian wrote:

Victor Bazarov :

>Galian wrote:

>>I have tried, and it don't work. "Cannot instantiate abstract class"
error. I don't now why. I tried different order, but it don't help.

Sounds like FAQ 5.8 should help. Check it out. It also can be that
your compiler is not capable; we'll know as you check out the FAQ.

Sorry Victor, but about what FAQ you talking? Where can I find it?

C++ FAQ: http://www.parashift.com/c++-faq-lite
FAQ 5.8: http://www.parashift.com/c++-faq-lit...t.html#faq-5.8

[Victor Bazarov]

Galian wrote:

Victor Bazarov :

>[..] check out the FAQ.

[..]
Sorry Victor, but about what FAQ you talking? Where can I find it?

Is that your first day here?

http://www.parashift.com/c++-faq-lite/

V
--
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I do not respond to top-posted replies, please don't ask

[Galian]

Sorry Victor, but about what FAQ you talking? Where can I find it?

Wow, I understand :) sorry.

This is my code. Task is next: I want write template class, CUnknown,
with implemented nessesary methods (Queryinterface , Release ...), to
use it for other classes.

CUnknown:

template < class ClassType, REFIID ObjectIID >
class CUnknown : public IUnknown
{
protected:
// IUnknown methods.
virtual STDMETHODIMP QueryInterface( REFIID riid, void** ppv )
{
if ( ppv == NULL )
{
return E_POINTER;
}
if ( riid == *ObjectIID || riid == IID_IUnknown )
{
*ppv = static_cast< ClassType* >( this );
AddRef();
return S_OK;
}
*ppv = NULL;
return E_NOINTERFACE;
}

virtual STDMETHODIMP_( ULONG ) AddRef()
{
return InterlockedIncr ement( &m_cRef );
}

virtual STDMETHODIMP_( ULONG ) Release()
{
LSCOPE( "CMediaBuffer:: Release" );
LONG lRef = InterlockedDecr ement( &m_cRef );
if ( lRef == 0 )
{
delete this;

// m_cRef is no longer valid! Return lRef.
}
return lRef;
}

LONG m_cRef;
};

#include "Unknown.h"

class ISMSNotificatio nHandler
{
public:
virtual void HandleSMSMessag eReceived( const CEOID messageID ) = 0;
};

// IMAPIAdviseSink also derived from IUnknown

class CAdviseSinc
// This is my CUnknown,but anyway "Cannot instantiate abstract
class" error
: public virtual CUnknown< CAdviseSinc, IID_IMAPIAdvise Sink >
, public virtual IMAPIAdviseSink
{
public:
CAdviseSinc();
~CAdviseSinc();

private:
ULONG OnNotify( ULONG cNotif, LPNOTIFICATION lpNotifications );
};

>>Is that your first day here?

Actually in this group yes, but not in other, I am sorry.