读《COM原理与应用》第二章随笔（模似的虚函数表）

今天下了这本书，看到第二章到半，书中用C描述了一个虚函数表的过程，不过代码不完全，所以就写了个，
刚刚接触COM~

/*
 *                         pVtable           vtable
 *  接口指针 ---> 虚函数表指针 ---> 指针函数1 --->
 *                                             指针函数2 ---> 对象实现
 *                                             指针函数3 --->
 */

// 模似的虚函数表
#include <stdio.h>
#include <stdlib.h>

// 前向声明
struct IDictionaryVtable;

// 模似接口指针
struct IDictionary
{
 // 虚函数表指针
 IDictionaryVtable *pVtable; 
};

// 模拟的虚函数表
struct IDictionaryVtable
{
 bool (*Initialize)( IDictionary *pThis );
 bool (*LoadLibrary)( IDictionary *pThis, char *source );
 bool (*FreeLibrary)( IDictionary *pThis );
};

void InitVtable( IDictionary *pInterface );
bool InitFoo( IDictionary *pThis );
bool LoadFoo( IDictionary *pThis, char *pString );
bool FreeFoo( IDictionary *pThis );

int main()
{
 // 实现接口指针
 IDictionary *pi = (IDictionary*) malloc( sizeof( IDictionary ) );

    InitVtable( pi );

 printf( "pi: %X\n" );
 printf( "pi->pVtable: %X\n", pi->pVtable );

    pi->pVtable->Initialize( pi );
    pi->pVtable->LoadLibrary( pi, "Phoebe" );
    pi->pVtable->FreeLibrary( pi );

    return 0;
}

// 初始化虚函数表
void InitVtable( IDictionary *pInterface )
{
 pInterface->pVtable = (IDictionaryVtable*) malloc( sizeof( IDictionaryVtable ) );
 pInterface->pVtable->Initialize = InitFoo;
    pInterface->pVtable->LoadLibrary = LoadFoo;
    pInterface->pVtable->FreeLibrary = FreeFoo;
}

// 初始化过程
bool InitFoo( IDictionary *pThis )
{
    printf( "Init function: pThis->pVtable: %X\n", pThis->pVtable );
    return true;
}

// 加载过程
bool LoadFoo( IDictionary *pThis, char *pString )
{
    printf( "Load function: pThis->pVtable: %X pString: %s\n", pThis->pVtable, pString );
    return true;
}

// 释放过程
bool FreeFoo( IDictionary *pThis )
{
    printf( "Free function: pThis->pVtable: %X\n", pThis->pVtable );
    return true;
}