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C++设计模式原型模式

article 2024/10/18 11:11:45

原型模式是一种创建型设计模式，它使用一个现有的对象实例作为原型，并通过复制该原型来创建新的对象实例。这种方法避免了每次都需要重新创建复杂对象的问题。

下面是一个简单的 C++11 示例，展示了如何使用原型模式：

假设我们有一个 Shape 类，它代表几何形状，并且可以被复制。我们将创建一个 Shape 类及其派生类 Circle 和 Rectangle，并且实现一个 clone 方法来克隆这些对象。

#include <iostream>
#include <memory>

// Base class for shapes
class Shape {
public:
    virtual ~Shape() {}

    // Pure virtual function to clone the shape
    virtual Shape* clone() const = 0;

    // Virtual destructor for polymorphic deletion
    virtual void draw() const = 0;
};

// Derived class representing a Circle
class Circle : public Shape {
public:
    Circle(int radius) : radius_(radius) {}

    Shape* clone() const override {
        return new Circle(*this);
    }

    void draw() const override {
        std::cout << "Drawing Circle with radius: " << radius_ << std::endl;
    }

private:
    int radius_;
};

// Derived class representing a Rectangle
class Rectangle : public Shape {
public:
    Rectangle(int width, int height) : width_(width), height_(height) {}

    Shape* clone() const override {
        return new Rectangle(*this);
    }

    void draw() const override {
        std::cout << "Drawing Rectangle with width: " << width_ << " and height: " << height_ << std::endl;
    }

private:
    int width_;
    int height_;
};

// Function to demonstrate cloning
void demonstrateCloning() {
    Circle circle(5);
    Rectangle rectangle(10, 20);

    // Clone the shapes
    Shape* clonedCircle = circle.clone();
    Shape* clonedRectangle = rectangle.clone();

    // Draw the original and cloned shapes
    circle.draw();
    clonedCircle->draw();

    rectangle.draw();
    clonedRectangle->draw();

    // Clean up memory
    delete clonedCircle;
    delete clonedRectangle;
}

int main() {
    demonstrateCloning();
    return 0;
}

在这个示例中：