Template class usage

[Timothy Jewett]

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.

[Victor Bazarov]

Post by Timothy Jewett
I have a project that has a base class, inherited class and inherited class
class CSession
{
BOOL Method1();
BOOL Method2();

Not virtual?

Post by Timothy Jewett
};
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

[Timothy Jewett]

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

Post by Victor Bazarov

Post by Timothy Jewett
I have a project that has a base class, inherited class and inherited class
class CSession
{
BOOL Method1();
BOOL Method2();

Not virtual?

Post by Timothy Jewett
};
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?
template<class Session> class CHtml : public Session
{
};
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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