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 
", 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 
");
     /* 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：

1. Why does C++ not have reflection?
2. How can I add reflection to a C++ application?
3. https://my.oschina.net/u/1450061/blog/204563 

4. https://my.oschina.net/u/1450061/blog/204608

5. https://my.oschina.net/u/1450061/blog/204564

6. http://m.blog.csdn.net/article/details?id=9254239

7. http://blog.csdn.net/dengyunze/article/details/763558

8. http://www.ithao123.cn/content-9688046.html