不夠徹底的橋接方式 - 讀《設計模式》

劉偉主編的重點大學專業教才《設計模式》中關於橋接模式的一個例子11.3.1中用Java實現的一個橋接模式，實現的不夠精準:

既然採用的橋接模式，除了基類就不需要知道現實部分的類和其定義了。實現部分的接口完全可以Pen這個基類裏面去了。要不要“橋”何用。

用C++重寫一遍（沒辦法，至今不懂Java）：

class Color
{
public:
    virtual void bepaint (string pentype, string name) = 0;
};

class Pen
{
    Color* _color;
public:
    Pen(Color* color):_color(color){}
    void setcolor(Color* color)
    {
        _color = color;
    }
    void colorBepaint(string pentype,string name)
    {
        if (_color)
            _color->bepaint (pentype, name);
    }
    virtual void draw (string name) = 0;
};

class smallpen : public Pen
{
public:
    smallpen(Color* color): Pen(color){}
    void draw(string name)
    {
        this->colorBepaint ("小號筆畫", name);
    }
};

class bigpen : public Pen
{
public:
    bigpen (Color* color) : Pen (color) {}
    void draw (string name)
    {
        this->colorBepaint ("大號筆畫", name);
    }
};

class red : public Color
{
public:
    void bepaint (string pentype, string name)
    {
        mdlcout << pentype << "紅色" << name << endl;
    }

};

class blue : public Color
{
public:
    void bepaint (string pentype, string name)
    {
        mdlcout << pentype << "藍色" << name << endl;
    }

};

測試部分在mdl的main函數裏：

extern"C" DLLEXPORT int MdlMain
(
int     argc,
char**  argv
)
{
    Color* r = new red;
    Color* b = new blue;

    Pen* bp0 = new bigpen (r);
    Pen* sp0 = new smallpen (r);

    Pen* bp1 = new bigpen (b);
    Pen* sp1 = new smallpen (b);

    bp0->draw ("花朵");
    sp0->draw ("花朵");

    bp1->draw ("蝴蝶");
    sp1->draw ("蝴蝶");

    delete bp0;
    delete sp0;
    delete bp1;
    delete sp1;
    delete r;
    delete b;

    return EXIT_SUCCESS;
}