介面與類，功能與介面的分離

class ICompiler
{
    virtual void fn1() = 0;
    virtual void DestroyInstance() = 0;
};

class CCompiler:public ICompiler
{
public:
    static CCompiler *CreateInstance()
    {
        return new CCompiler;
    }
private:
    CCompiler();
    virtual ~CCompiler();
public:
    virtual void fn1();
    virtual DestroyInstance()
    {
 delete this;
    }
};

ICompiler *pCompiler = NULL;
pCompiler = CCompiler::CreateInstance();
if (pCompiler == NULL)
    return;
pCompiler->fn1(); 
pCompiler->DestroyInstance();

class CMyBase
{
public:
    CMyBase();
    ~CMyBase();
protect:
    ICompiler *GetComplier()
    {
        if (m_pCompiler == NULL)
        {
     m_pCompiler = CCompiler::CreateInstance();
 }
 return m_pCompiler;
    }
public:
    void func();
private:
    ICompiler *m_pCompiler;
};

class CMyApp:public CMyBase
{
public:
    CMyApp();
    ~CMyApp();
public:
    void func()
    {
        ICompiler *pCompiler = GetCompiler();
    }
};//定義結構或類的後面需加;