[转]主要C++流派，看看你是哪一流

挺哏儿的，我大概是4 + 5 + 9

1. 经典C++流：类是核心，例程多用C Runtime的，很少用模版，一般是正统教育的结果。
2. 古典C流：基本上当C用，偶尔用用对象，不使用异常，喜欢怀旧。
3. MFC流：秉承MFC的风格，主要使用MFC/ATL对象和Win32 API，不喜欢STL，用很多的宏把IDE的语法提示模块折磨到崩溃。
4. Portable流：以C Runtime和STL为主要工具，使用类和模版，不跨平台毋宁死。
5. Functional流：以模版和STL为主要武器，大量使用函数式语言的设计方法，并号称这才是真正的C++。
6. Win32流：多使用全局函数，偏爱Win32 API，但不排斥C Runtime，通常喜欢轻量级的程序，所以身材也比较苗条。
7. Java流：全面使用Java的风格，不能容许任何全局成员，但允许使用STL的集合类，写很多叫Factory的类。
8. COM流：喜欢AddRef()和Release()，大量使用接口，隐藏一切可以隐藏的东西，诵经的时候要把上帝替换成COM。
9. 戒律流：追求完美的C++程序，计较每一个const和throw()，极力避免不安全的cast，随身一定要带一本ISO C++手册。
10. 混沌流：其程序无常形，无恒道，变幻莫测，吾不知其名。

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Determine Perspective Lines With Off-page Vanishing Point

In perspective drawing, a vanishing point represents a group of parallel lines, in other words, a direction. For any point on the paper, if we want a line towards the same direction (in the 3d space), we simply draw a line through it and the vanishing point. But sometimes the vanishing point is too far away, such that it is outside the paper/canvas. In this example, we have a point P and two perspective lines L1 and L2. The vanishing point VP is naturally the intersection of L1 and L2. The task is to draw a line through P and VP, without having VP on the paper. I am aware of a few traditional solutions: 1. Use extra pieces of paper such that we can extend L1 and L2 until we see VP. 2. Draw everything in a smaller scale, such that we can see both P and VP on the paper. Draw the line and scale everything back. 3. Draw a perspective grid using the Brewer Method. #1 and #2 might be quite practical. #3 may not guarantee a solution, unless we can measure distances/p...

Chasing an IO Phantom

My home server has been weird since months ago, it just becomes unresponsive occassionally. It is annoying but it happens only rarely, so normally I'd just wait or reboot it. But weeks ago I decided to get to the bottom of it. What's Wrong My system set up is: Root: SSD, LUKS + LVM + Ext4 Data: HDD, LUKS + ZFS 16GB RAM + 1GB swap Rootless dockerd The system may become unresponsive, when the IO on HDD is persistantly high for a while. Also: Often kswapd0 has high CPU High IO on root fs (SSD) From dockerd and some containers RAM usage is high, swap usage is low It is very strange that IO on HDD can affect SSD. Note that when this happens, even stopping the IO on HDD does not always help. Usually restarting dockerd does not help, but rebooting helps. Investigation: Swap An obvious potential root cause is the swap. High CPU on kswapd0 usually means the free memory is low and the kernel is busy exchanging data between disk and swap. However, I tried the following steps, none of the...

Moving Items Along Bezier Curves with CSS Animation (Part 2: Time Warp)

This is a follow-up of my earlier article. I realized that there is another way of achieving the same effect. This article has lots of nice examples and explanations, the basic idea is to make very simple @keyframe rules, usually just a linear movement, then use timing function to distort the time, such that the motion path becomes the desired curve. I'd like to call it the "time warp" hack. Demo See the Pen Interactive cubic Bezier curve + CSS animation by Lu Wang ( @coolwanglu ) on CodePen . How does it work? Recall that a cubic Bezier curve is defined by this formula : \[B(t) = (1-t)^3P_0+3(1-t)^2tP_1+3(1-t)t^2P_2+t^3P_3,\ 0 \le t \le 1.\] In the 2D case, \(B(t)\) has two coordinates, \(x(t)\) and \(y(t)\). Define \(x_i\) to the be x coordinate of \(P_i\), then we have: \[x(t) = (1-t)^3x_0+3(1-t)^2tx_1+3(1-t)t^2x_2+t^3x_3,\ 0 \le t \le 1.\] So, for our animated element, we want to make sure that the x coordiante (i.e. the "left" CSS property) is \(...

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