7.1 Primpl模式

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#include <iostream>
#include <string>
#include <cstdio>

struct Person
{
        std::string name;
        void greet();

        Person();
        ~Person();
        class PersonImpl;
        PersonImpl *impl;
};

struct Person::PersonImpl
{
        void greet(Person* p);
};

Person::Person()
        : impl(new PersonImpl) {}

Person::~Person() { delete impl; }

void Person::greet()
{
        impl->greet(this);
}
void Person::PersonImpl::greet(Person* p)
{
        printf("hello %s\n", p->name.c_str());
}

int main(void)
{
        Person k;
        k.name = "sss";
        k.greet();
        return 0;
}

7.2 桥接模式介绍

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#include <iostream>

struct Renderer
{
        virtual void render_circle(float x, float y, float radius) = 0;
};

struct VectorRenderer : Renderer
{
        void render_circle(float x, float y, float radius) override
        {
                std::cout << "Rasterizing circle of radius " << radius << std::endl;
        }
};

struct RasterRenderer : Renderer
{
        void render_circle(float x, float y, float radius) override
        {
                std::cout << "Drawing a vector circle of radius " << radius << std::endl;
        }
};

struct Shape
{
protected:
        Renderer& renderer;
        Shape(Renderer& renderer) : renderer{ renderer } {}
public:
        virtual void draw() = 0;
        virtual void resize(float factor) = 0;
};

struct Circle : Shape
{
        float x, y, radius;
        Circle(Renderer& renderer, float x, float y, float radius)
                : Shape{renderer}, x{x}, y{y}, radius{radius} {}

        void draw() override
        {
                renderer.render_circle(x, y, radius);
        }

        void resize(float factor) override
        {
                radius *= factor;
        }
};

int main(void)
{
        RasterRenderer rr;
        Circle raster_circle{ rr, 5, 5, 5 };
        raster_circle.draw();
        raster_circle.resize(2);
        raster_circle.draw();

        return 0;
}