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Loading classes from a library
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I have a problem with loading classes from a lib ( for win32 and linux ) at runtime.
That's my code:
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/*
Exectuable source -- file: main.cpp
*/
#include <iostream>
#include <fstream>
#include <string>
#include <dlfcn.h>
using namespace std;
class CBase
{
protected:
int x;
int y;
public:
virtual ~CBase( void ) = 0;
virtual void add ( int _x, int _y ) = 0;
virtual void move ( int _x, int _y ) = 0;
virtual void print ( void ) = 0;
};
int main()
{
ifstream f;
f.open ( "class.txt" );
if ( f == NULL )
{
cout << "No \"class.txt\" file found!" << endl;
return -1;
}
string classname = "EMPTY";
f >> classname;
f.close();
void * sofile = NULL;
sofile = dlopen ( "./libC.so", RTLD_LAZY );
if ( sofile == NULL )
{
cout << "ERROR!(1) -> " << dlerror() << endl;
return -1;
}
typedef CBase * ( * new_class ) ( void );
typedef void ( * delete_class ) ( CBase * );
new_class cbase_new = NULL;
delete_class cbase_delete = NULL;
string str = classname + "_new";
cbase_new = (new_class) dlsym ( sofile, str.c_str() );
str = classname + "_delete";
cbase_delete = (delete_class) dlsym ( sofile, str.c_str() );
if ( cbase_new == NULL || cbase_delete == NULL )
{
cout << "ERROR! -> " << dlerror() << endl;
dlclose( sofile );
return -1;
}
CBase * t = cbase_new();
if ( t != NULL )
{
t->add( 2, 4 );
t->print();
t->move( 4, 10 );
t->print();
}
cbase_delete ( t );
dlclose( sofile );
return 0;
}
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/*
Lib source -- file: c.cpp
*/
#include <iostream>
class CBase
{
protected:
int x;
int y;
public:
virtual ~CBase( void ) = 0;
virtual void add ( int _x, int _y ) = 0;
virtual void move ( int _x, int _y ) = 0;
virtual void print ( void ) = 0;
};
class CTest : public CBase
{
public:
void add ( int _x, int _y );
void move ( int _x, int _y );
void print ( void );
};
void CTest::add ( int _x, int _y )
{
x = _x;
y = _y;
}
void CTest::move ( int _x, int _y )
{
x += _x;
y += _y;
}
void CTest::print ( void )
{
std::cout << "X: " << x << std::endl;
std::cout << "Y: " << y << std::endl;
}
extern "C"
{
CBase * ctest_new ( void )
{
return new CTest;
}
void ctest_delete ( CBase * p )
{
delete p;
}
}
I only did it on linux for testing. That's why i have no defines/functions for windows.
This is the console output:
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./ClassFromLib ERROR!(1) -> ./libC.so: undefined symbol: _ZN5CBaseD2Ev
C++ saves symbols of functions and structures in a different way into a lib than C.
I do not know, why it can't load this class : (
can someone help me ?