C++Talk.NET

Leo Wong · Guest

Hi,

With a lot of classes and virtual functions to work with, it is
increasingly difficult to track incorrectly defined virtual functions
as described here in a previous thread:
http://groups.google.com/group/comp.std.c++/browse_thread/thread/57f9247880e
637d9/e862e15f8219a963?lnk=st&q=&rnum=5#e862e15f8219a963

I am trying to create some macros to address some but not all of the
problems:

#ifdef _DEBUG

#define VIRTUAL(Ret, Func) struct __dummy_##Func{}; virtual
__dummy_##Func* __virtual_##Func() { return 0; } virtual Ret Func
#define OVERRIDE(Ret, Func) void __override_##Func() {
__super::__virtual_##Func(); } virtual Ret Func
#define SEALED_OVERRIDE(Ret, Func) void __virtual_##Func(int) {
__super::__virtual_##Func(); } virtual Ret Func

#else

#define VIRTUAL(Ret, Func) virtual Ret Func
#define OVERRIDE(Ret, Func) virtual Ret Func
#define SEALED_OVERRIDE(Ret, Func) virtual Ret Func

#endif

class CBaseClass
{
public:

VIRTUAL(void,VFunc1)(int)
{
cout << "CBaseClass::VFunc1\n";
}

VIRTUAL(void,VFunc2)(double)
{
cout << "CBaseClass::VFunc2\n";
}
};

class CDerivedClass : public CBaseClass
{
public:

OVERRIDE(void,VFunc1)(int)
{
cout << "CDerivedClass::VFunc1\n";
}

SEALED_OVERRIDE(void,VFunc2)(double)
{
cout << "CDerivedClass::VFunc2\n";
}

// OVERRIDE(void,VFunc3)(char) // <-- compile time error, base
virtual
not defined
// {
// cout << "CDerivedClass::VFunc3\n";
// }
};

class CDerivedClass2 : public CDerivedClass
{
public:

OVERRIDE(void,VFunc1)(int)
{
cout << "CDerivedClass2::VFunc1\n";
}

// OVERRIDE(void,VFunc2)(double) // <-- compile time error, sealed
virtual function
// {
// cout << "CDerivedClass2::VFunc1\n";
// }
};

I haven't tested these extensively but one of the problem is that the
macros are not taking into account the parameters in the virtual
functions. The side effect is that they won't allow you to declare
multiple virtual functions with the same name in the same class with
different parameters.

Is there any facility in the boost library which will allow me to
'merge' all input parameter types into a string?

Thanks,

Leo

[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]

Thorsten Ottosen · Guest

Leo Wong wrote:

Gene Bushuyev · Guest

"Leo Wong" <wong.kam.keung (AT) gmail (DOT) com> wrote in message
news:1154623674.772326.196750 (AT) h48g2000cwc (DOT) googlegroups.com...

StepNRazor · Guest

I tried to reference the thread you suplied but the link did not work.
so from I seen in your thread I am going to reply to what I seen.

I belive using good desrciptive documentation in your class header
files would be more effective to users of your code to know the status
of your class members and how they relate to base or derived classes.

In your .cpp fole is where I would use ifdef debug switches and once
again documentation comments.

Your mechinism might work but in filtering classes by debug and or
inheritence issue but it lacks in describing ussage and describing the
ussage in documentation avialates the need for macro filtering.

Joe

Leo Wong wrote: