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// $Id$
// To use the export macros with a DLL, a file will need to be
// created (see ACE_wrapper/bin/generate_export_file.pl) and
// included. This file defines Test_Export (and the
// TEST_SINGLETON_* macros).
#include "test_export.h"
#include "ace/Singleton.h"
#define RETVAL 42
// To expose a function outside of a DLL, use the *_Export
// at the beginning of the function declaration.
Test_Export int test_function ();
// To expose data, put use the *Export at the beginning
// of the variable declaration.
Test_Export int test_variable;
// To expose a class, put the *_Export between "class"
// and the class name.
class Test_Export test_class
{
public:
int method ();
};
// ACE_Singleton and its relatives are special cases. The problem is
// that ACE_Singleton is a template. If the singleton is used in both
// the DLL and the executable linking the DLL, then two instances of
// the singleton will be used (which defeats the purpose of a Singleton).
//
// This occurs because the ACE_Singleton template is expanded in both
// places because Visual C++ does this automatically by including
// the template source. This in turn creates two copies of the static
// member variable.
//
// So to get around this problem, the *_SINGLETON_DECLARE macro is
// used to instruct the compiler to not create the second copy in the
// program.
//
// Another workaround for this is to not to expose the Singleton itself
// to the outside world, but to instead supply a function or static
// member function that returns the singleton to the executable
// (like get_dll_singleton () does below).
typedef ACE_Singleton<test_class, ACE_Null_Mutex> TEST_SINGLETON;
TEST_SINGLETON_DECLARE (ACE_Singleton, test_class, ACE_Null_Mutex);
Test_Export test_class *get_dll_singleton ();
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