C语言如何开发简单的插件

linux 通过dlopen来实现：

#include "polygon.h"
#include <stdlib.h>
#include <dlfcn.h>

int main()
{
typedef CPolygon* create_t();

void * handle = dlopen("./triangle.so", RTLD_LAZY);

if( !handle )
{
std::cerr << dlerror() << std::endl;
exit(1);
}

create_t * create_triangle = (create_t *)dlsym(handle, "create");

CPolygon * pObj = create_triangle();

if( 0 != pObj )
{
pObj->area();
}

delete pObj;

dlclose(handle);
return 0;
}

生成动态库：g++ -fPIC -shared triangle.cpp -o triangle.so

生成test主函数：g++ -fPIC test.cpp -ldl -o test

具体demo：http://files.cnblogs.com/files/hero4china/plugins_1.zip

/***************************************************************************/
/*                             dynclass.h                                  */
/*  使用的时候#include "dynclass.h"，在类的声明后使用DYNCLASS(类名)注册*/
/***************************************************************************/

#ifndef __DYNAMIC_H__
#define __DYNAMIC_H__

#include <cstdio>
#include <string>
#include <typeinfo>
#include <cstring>

#if !defined ( DYN_DECLARE )
#define DYN_DECLARE(class_name) DYN_CLASS::CFactory<class_name> class_name
#endif

#if !defined ( DYN_CREATE )
#define DYN_CREATE(class_name)   DYN_CLASS::Create(class_name)
#endif

namespace DYN_CLASS
{
/* create object by class name */
void * Create( const char * class_name );

/* interface of class factory*/
class CAbstractFactory
{
public:
virtual void * Create( const char * class_name ) = 0;
};

/* list of class factory */
class CFactoryList
{
friend void * Create( const char * class_name );
private:
static CFactoryList * _head;
CFactoryList        * m_next;
CAbstractFactory    * m_item;
public:
CFactoryList( CAbstractFactory * fact );
virtual ~CFactoryList( void );
};

/* ctor of CFactoryList, add a class factory to list */
inline CFactoryList::CFactoryList( CAbstractFactory * fact )
: m_item( fact )
{
m_next = _head;
_head = this;
}

#if defined ( _MSC_VER )
/* disable warning for the following line : CFactory( void ): m_item( this ) {} */
#pragma warning(disable : 4355)
#endif

/* realization of class factory */
template <class t>
class CFactory: public CAbstractFactory
{
static t     _object;
CFactoryList m_item;

public:

/* add itself to list of class factory when constructed */
CFactory( void ) : m_item( this ) {}

virtual ~CFactory() {}

/* create object of this class if matched */
void * Create( const char * class_name )
{
std::string strClassName;

#if defined (_MSC_VER )
strClassName = ( "class " );
#else
char szSize[4] = {0};
sprintf(szSize, "%d", strlen(class_name) );
strClassName = szSize;
#endif
strClassName += class_name;
printf("%s vs %s \n", typeid(_object).name(), strClassName.c_str());
/* RTTI support */
return !strcmp( typeid(_object).name(), strClassName.c_str() )
? (void*)( new t ) : 0 ;

}
};
}
#endif /* __DYNAMIC_H__ */

/***************************************************************************/
/*                             dynclass.cpp                                */
/***************************************************************************/
#include "dynclass.h"

namespace DYN_CLASS
{
CFactoryList * CFactoryList::_head = 0;

void *Create( const char * class_name )
{
void * new_object = 0;
const CFactoryList * cur = CFactoryList::_head;

for( ; cur ; cur = cur->m_next )
{
printf("find \n");
/* if class_name matched, object will then be created and returned */
if( new_object = cur->m_item->Create(class_name) )
{
break;
}
}

return new_object;
}

/* delete linkage from CFactoryList when some class factory destroyed */
CFactoryList::~CFactoryList( void )
{
CFactoryList ** m_nextp = &CFactoryList::_head;

for( ; *m_nextp ; m_nextp = &(*m_nextp)->m_next )
if( *m_nextp == this )
{
*m_nextp = (*m_nextp)->m_next;
break;
}
}
}

参考：

Why does C++ not have reflection?

How can I add reflection to a C++ application?
https://my.oschina.net/u/1450061/blog/204563 https://my.oschina.net/u/1450061/blog/204608 https://my.oschina.net/u/1450061/blog/204564 http://m.blog.csdn.net/article/details?id=9254239 http://blog.csdn.net/dengyunze/article/details/763558 http://www.ithao123.cn/content-9688046.html