深入解析C++对象模型:效率与实现机制

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"《深入理解C++对象模型》是一本探讨C++面向对象编程底层机制的书籍,由Lipman撰写,与C++ Primer类似,但读者反馈在表述上可能存在冗余和不清晰之处。本书重点讲解了构造函数语义、临时对象生成、封装支持、继承以及虚函数和虚继承等核心概念。通过理解这些底层实现,读者能够更高效、更有信心地编写代码。Lipman澄清了一些关于C++开销和复杂性的误解,同时也指出了潜在的成本和权衡。他追溯了各种实现模型的起源,预测了它们可能的发展,并解释了为何采取当前的设计。此外,书中还分析了C++对象模型对程序语义的影响以及如何影响你的程序设计。" 在这本深入解析C++对象模型的著作中,作者Lipman首先带领读者探索隐藏在C++面向对象支持背后的程序行为。这包括了对构造函数的深入剖析,这些构造函数在创建和初始化对象时起着关键作用。通过理解构造函数的内部工作原理,程序员可以更好地管理对象生命周期,避免内存泄漏和悬挂指针等问题。 其次,书中详尽阐述了面向对象特性(如类、继承、多态性等)的基本实现,并讨论了这些特性所带来的权衡。例如,虚函数使得动态绑定成为可能,但也可能导致额外的运行时开销;虚继承旨在解决多重继承中的二义性问题,但同时也增加了类层次结构的复杂性。 再者,Lipman深入研究了这些对象模型对程序性能的影响,特别是在程序转换层面。这涉及到编译器如何优化代码,以及如何在保持灵活性的同时提高执行效率。对于关心性能的开发者来说,这部分内容提供了宝贵的洞见,帮助他们在设计时做出明智的决策。 书中还涵盖了C++对象模型如何影响程序的行为和设计。比如,封装确保了数据的安全性,但过度的封装可能会降低代码的可读性和可维护性。继承可以实现代码重用,但不恰当的继承关系可能导致难以维护的类层次结构。 《深入理解C++对象模型》是C++程序员进阶的必备读物,它揭示了C++语言底层的工作原理,有助于提升程序员对C++特性的深入理解和应用能力,从而编写出更高效、更可靠的代码。尽管有些读者认为其表述略显冗余,但这并不影响它在C++学习和实践中作为一本有价值的参考书。

帮我写出以下java代码:Add a class Bubble that extends Shape. The Bubble class has an instance variable called radius of type double that represents the radius of the bubble. The constructor of the Bubble class takes an x and a y as arguments, which represent the position of the new bubble. The radius of a new bubble is always 10 and never changes after that. The isVisible method indicates whether the bubble is currently visible inside a window of width w and height h (position (0, 0) is in the upper-left corner of the window). The bubble is considered visible if at least one pixel of the bubble is visible. Therefore a bubble might be visible even when its center is outside the window, as long as the edge of the bubble is still visible inside the window. The code of the isVisible method is a little bit complex, mostly because of the case where the center of the circle is just outside one of the corners of the window. So here is the code of the isVisible method, which you can directly copy-paste into your assignment: // Find the point (wx, wy) inside the window which is closest to the // center (x, y) of the circle. In other words, find the wx in the // interval [0, w - 1] which is closest to x, and find the wy in the // interval [0, h - 1] which is closest to y. // If the distance between (wx, wy) and (x, y) is less than the radius // of the circle (using Pythagoras's theorem) then at least part of // the circle is visible in the window. // Note: if the center of the circle is inside the window, then (wx, wy) // is the same as (x, y), and the distance is 0. public boolean isVisible(int w, int h) { double x = getX(); double y = getY(); double wx = (x < 0 ? 0 : (x > w - 1 ? w - 1 : x)); double wy = (y < 0 ? 0 : (y > h - 1 ? h - 1 : y)); double dx = wx - x; double dy = wy - y; return dx * dx + dy * dy <= radius * radius; } The isIn method indicates whether the point at coordinates (x, y) (which are the arguments of the method) is currently inside the bubble or not. The edge of the bubble counts as being inside of the bubble. HINT: use Pythagoras's theorem to compute the distance from the center of the bubble to the point (x, y). The draw method uses the graphics object g to draw the bubble. HINT: remember that the color of the graphics object g is changed in the draw method of the superclass of Bubble. Also add a testBubble method to test all your methods (including inherited methods, but excluding the isVisible method, which I provide, and excluding the draw method since it requires as argument a graphics object g that you

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