Re: Virtual Destructor - Implication & Specification
On Apr 3, 10:38 am, "Le Chaud Lapin" <jaibudu...@gmail.com> wrote:
...
***** EXE.CPP
// EXE.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include "..\Foo.hpp"
int _tmain(int argc, _TCHAR* argv[])
{
Abstract *pAbstract = gimme_abstract();
Concrete *pConcrete = gimme_concrete();
delete pAbstract;
delete pConcrete;
return 0;
}
***** DLL.CPP
// DLL.cpp : Defines the entry point for the DLL application.
//
#include "stdafx.h"
#define DEFINE_EXPORTS
#include "..\Foo.hpp"
Abstract * gimme_abstract ()
{
return new Abstract;
}
Concrete * gimme_concrete ()
{
return new Concrete;
}
BOOL APIENTRY DllMain( HMODULE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
)
{
return TRUE;
}
What if you compile and link dll.cpp in MinGW and compile and link
exe.cpp in MSVC++? Then you'll have called the glibc version (most
likely) of operator new, and the MSVCRT version (most likely) of
operator delete. Matching destructors will be called because they're
virtual, but that's not the point here. You're mismatching operators
new and delete. That's not a good thing.
The only way that you can guarantee that they match up is to make sure
that you use the same build environment for both. That's not much of
a guarantee. People use DLL versions of open-source libraries all the
time in Windows. If the library designer isn't cautious enough to
either stick to a C-only interface, overload the new and delete
operators, or use a smart pointer that handles deallocation in the
same binary code as the allocation, then it's broken.
The only way to get around that is to override operator new and
operator delete in your classes, to guarantee that you call a
deallocation routine that matches your allocation routine. The
destructor isn't the same as the deallocator, and both have to be
considered. You're only considering one in your code.
HTH,
John
--
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]