SEARCH KEYWORD -- Code coverage

  Don't Overload #nil?

There’s a popular post on Hacker News about writing confident code by, among other things, overloading Object#nil? and returning “null objects” instead of nil itself.DO NOT DO THIS.In Ruby, all objects (except nil itself) coerce to the boolean value true. Your object will be nil and true at the same time. Bad things will happen. Your coworkers will cry. Sad people from around the world will ask bewildering questions on your mailing list.Here’s what happen...

   Ruby,#nil,Overload,Object     2011-11-10 10:50:22

  A Tiny MySQL++ Tutorial; C++ and MySQL; MySQL++ Example

I wrote a post about how to install MySQL++ and I thought I will write a quick tutorial on how to use it too. This is a very basic MySQL++ program and it’s very self explanatory: #include <mysql++.h> #include <stdlib.h>   using namespace std; using namespace mysqlpp;   int main() { try { Connection conn(false); conn.connect("DB NAME", "DB HOST probably localhost", "DB USER", "DB PASS"); Query query = conn.query(); } catch (BadQuery er...

   C++,Example,MySQL++,Insert,API     2011-09-05 02:12:40

  How Computers Boot Up

The previous post described motherboards and the memory map in Intel computers to set the scene for the initial phases of boot. Booting is an involved, hacky, multi-stage affair – fun stuff. Here’s an outline of the process: An outline of the boot sequence Things start rolling when you press the power button on the computer (no! do tell!). Once the motherboard is powered up it initializes its own firmware – the chipset and other tidbits – and tries to ...

   Computer,Boot-up,Rationale     2012-04-11 13:43:02

  HTML above flash (transparency + z-index)

We have faced this problem many of the times. When we want to display some message on top of all layers on a page or use some feature like jQuery light boxes. Normally the flash file continues to shine through the page. No matter what you do with layering the dom elements using z-index.See the layering flash content problem definition here.Before this, people used to dodge this issue with some fixes like hiding the flash area completely and then showing a static image of...

   HTML,Flash,Above,z-index,wmode,transpare     2011-05-01 15:46:34

  Generate first N prime numbers

Recently I am taking an online course named "Startup Engineering" on coursera. There is one assignment which is to use NodeJS to write a program to generate the first 100 prime numbers. This may be very easy for many people. Here I just want to share with you the code to generate not only the first 100 prime numbers. but also any number of prime numbers. Below is the code snippet: //Helper class to generate prime numbers var PrimeProcessor=(function(){ var primeArray=[]; functio...

   Algorithm,Prime number,NodeJS,coursera,JavaScript     2013-06-29 22:08:22

  do {...} while (0) in macros

If you are a C programmer, you must be familiar with macros. They are powerful and can help you ease your work if used correctly. However, if you don't define macros carefully, they may bite you and drive you crazy. In many C programs, you may see a special macro definition which may seem not so straightforward. Here is one example: #define __set_task_state(tsk, state_value) \ do { (tsk)->state = (state_value); } while (0) There are many this kind of macros which uses do{...}while(0)...

   C,macro,C++     2014-01-23 07:16:13

  How expensive is a MySQL query?

Database access speed is always the bottle neck of many applications. Many application have large amount of data to search, retrieve and display nowadays. How do we improve the performance of our applications, how do we reduce the cost of database access? Apart from the design of database, the quality of the query is also one important factor to take care.  But before that, we need to know how much network traffic a query will consume. Yunyang,Zhang from Nubee in Singapore did some research...

   MySQL,Network traffic,Query     2013-04-09 05:13:33

  Notes on Programming in C

Introduction       Kernighan and Plauger's The Elements of Programming Style was an important and rightly influential book.  But sometimes I feel its concise rules were taken as a cookbook approach to good style instead of the succinct expression of a philosophy they were meant to be.  If the book claims that variable names should be chosen meaningfully, doesn't it then follow that variables whose names are small essays on their use are even better?  Isn't MaximumV...

   C,Notes,Tips     2011-12-09 07:55:47

  In defence of Objective-C

An unashamed apologist’s perspective on the loveliest language i’ve worked with.I’ve worked with a lot of programming languages in my time. Not a huge number, mind you, but enough that i can say that i’m open minded and seasoned about it. And, as they say: ‘Don’t feed the trolls’ – well, i’m about to do exactly that: feed the trolls at work who love to rag on about how awful obj-c is! So here i go, foolishly treading where no sensible...

   Apple,Objective-C,Syntax,Defense,Memory management     2011-10-17 11:28:39

  How to check which Ohai plugin hangs in chef client run

Ohai plugins are very important components in chef client which aims to provide resource management automation on a server. The data discovered by Ohai plugins are describing the current state of the server and they will be used to maintain the server in a desired state. Each Ohai plugin discovers a specific pierce of information about the server such as cpu, memory, middleware etc. However, there are rare occasions(well I am a bit optimistic here) someone may find that the chef client...

   HOW TO,CHEF-CLIENT,OHAI,UPTIME,HANG     2017-12-24 22:09:59

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