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From: Timothy Jewett on 22 Apr 2010 13:53
I have a project that has a base class, inherited class and inherited class

class CSession
{
public:
BOOL Method1();
BOOL Method2();
};

class CHtml : public CSession
{
BOOL Method1();
BOOL Method2();
};

class CClient : public CHtml
{
BOOL Method1();
BOOL Method2();
};

I would like to Inherit the CHtml class from a different base class

class CSessionSSL : CSecure
{
BOOL Method1();
BOOL Method2();
};

class CHtmlSSL : public CSessionSSL
{
BOOL Method1();
BOOL Method2();
};

class CClientSSL : public CHtmlSSL
{
BOOL Method1();
BOOL Method2();
};

without redefining all the methods in the CHtml & CClient code inherited
from the new base class. I assume this can be done with templates but I do
not understand how to instantiate the top classes CClient & CClientSSL?

Thanks in advance.
--

Timothy Jewett
Jewettware(a)online.nospam
From: Victor Bazarov on 22 Apr 2010 15:07
Timothy Jewett wrote:
> I have a project that has a base class, inherited class and inherited class
>
> class CSession
> {
> public:
> BOOL Method1();
> BOOL Method2();

Not virtual?

> };
>
> class CHtml : public CSession
> {
> BOOL Method1();
> BOOL Method2();
> };
>
> class CClient : public CHtml
> {
> BOOL Method1();
> BOOL Method2();
> };
>
> I would like to Inherit the CHtml class from a different base class
>
> class CSessionSSL : CSecure
> {
> BOOL Method1();
> BOOL Method2();
> };
>
> class CHtmlSSL : public CSessionSSL
> {
> BOOL Method1();
> BOOL Method2();
> };
>
> class CClientSSL : public CHtmlSSL
> {
> BOOL Method1();
> BOOL Method2();
> };
>
> without redefining all the methods in the CHtml & CClient code inherited
> from the new base class. I assume this can be done with templates but I do
> not understand how to instantiate the top classes CClient & CClientSSL?

You haven't given us enough to go on, I suspect. Are you looking to
implement 'CClientSSL' by utilizing some 'CClient' functionality but
don't want to rewrite/redefine it? And only redefine some small portion
of the base 'Session' class?

So, if you define your CHtml as a template like this:

template<class Session> class CHtml : public Session
{
};

then you can define your Client classes like this:

class CClient : public CHtml<CSession> ...

and

class CClientSSL : public CHtml<CSessionSSL> ...

.. I am not sure what exactly you're gaining here. Get a copy of Andrei
Alexandrescu's "Modern C++ Design", and read about "policy-based
design". That's pretty much what you want, you just need to connect
your "clients" using different "sessions".

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask
From: Timothy Jewett on 23 Apr 2010 11:07
You are correct in what I am doing, which is to just have Client objects
connect to to different base classes.
In the example both CClient and CHtml need to be the same code base so do I
define CClient like this:

template<class CHtml<CSession>> class CClientBase : public CHtml

instantiate:
CClient :public CClientBase< Chtml <CSession> >
&
CClientSSL : public CClientBase< CHtml <CSessionSSL> >

I will follow up on that book, Thanks again.
--
Timothy Jewett
Jewettware(a)online.nospam


"Victor Bazarov" wrote:

> Timothy Jewett wrote:
> > I have a project that has a base class, inherited class and inherited class
> >
> > class CSession
> > {
> > public:
> > BOOL Method1();
> > BOOL Method2();
>
> Not virtual?
>
> > };
> >
> > class CHtml : public CSession
> > {
> > BOOL Method1();
> > BOOL Method2();
> > };
> >
> > class CClient : public CHtml
> > {
> > BOOL Method1();
> > BOOL Method2();
> > };
> >
> > I would like to Inherit the CHtml class from a different base class
> >
> > class CSessionSSL : CSecure
> > {
> > BOOL Method1();
> > BOOL Method2();
> > };
> >
> > class CHtmlSSL : public CSessionSSL
> > {
> > BOOL Method1();
> > BOOL Method2();
> > };
> >
> > class CClientSSL : public CHtmlSSL
> > {
> > BOOL Method1();
> > BOOL Method2();
> > };
> >
> > without redefining all the methods in the CHtml & CClient code inherited
> > from the new base class. I assume this can be done with templates but I do
> > not understand how to instantiate the top classes CClient & CClientSSL?
>
> You haven't given us enough to go on, I suspect. Are you looking to
> implement 'CClientSSL' by utilizing some 'CClient' functionality but
> don't want to rewrite/redefine it? And only redefine some small portion
> of the base 'Session' class?
>
> So, if you define your CHtml as a template like this:
>
> template<class Session> class CHtml : public Session
> {
> };
>
> then you can define your Client classes like this:
>
> class CClient : public CHtml<CSession> ...
>
> and
>
> class CClientSSL : public CHtml<CSessionSSL> ...
>
> .. I am not sure what exactly you're gaining here. Get a copy of Andrei
> Alexandrescu's "Modern C++ Design", and read about "policy-based
> design". That's pretty much what you want, you just need to connect
> your "clients" using different "sessions".
>
> V
> --
> Please remove capital 'A's when replying by e-mail
> I do not respond to top-posted replies, please don't ask
> .
>
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