Re: static member variables and DLLS

DDD <>
Sun, 21 Aug 2011 07:51:19 -0700 (PDT)
On Aug 13, 3:31 am, rk <> wrote:


I have run into similar problems before and have used convoluted
strategies to resolve the issue. This time I want to undertand this
problem better. I have the following scenario.

My dll has the files A.cpp, B.hpp and someother_file.cpp
/// A.hpp

EXPORT_CLASS class A : public B
      static const char *flag_;

      virtual const char* flag() { return A::flag_; }


/// B.hpp
    virtual const char * flag() = 0;


///// somother_file.cpp
#include "A.hpp"

void test(B& b)
   if( b->flag() == A::flag_ )
        //// Do something...


/// main.cpp
#include <factory.hpp>

int main(int argc, char *argv[])
    B* b = factory_create_a();


The issue is that the condition b->flag() == A::flag_ fails. I have
looked at the dissasembly and the addresses being compared are
different, i.e. b->flag() returns ad different address than A::flag_.

It would be great to get an Idea of what is going on here?

If we pretend char* flag_ is int flag_

EXPORT_CLASS class A : public B
      static const int flag_;

      virtual const int flag() { return A::flag_; }


 Then we can see the function return a copy value of flag_, but not
flag_ itself.

So, char * returned by the function is not char*flag_ int the static

Is that right?

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