Re: Template class usage

From:
Victor Bazarov <v.Abazarov@comAcast.net>
Newsgroups:
microsoft.public.vc.language
Date:
Thu, 22 Apr 2010 15:07:17 -0400
Message-ID:
<hqq6p6$n6m$1@news.datemas.de>
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
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