Tutorial by Examples: r

async.parallel(tasks, afterTasksCallback) will execute a set of tasks in parallel and wait the end of all tasks (reported by the call of callback function). When tasks are finished, async call the main callback with all errors and all results of tasks. function shortTimeFunction(callback) { set...

async.series(tasks, afterTasksCallback) will execute a set of tasks. Each task are executed after another. If a task fails, async stops immediately the execution and jump into the main callback. When tasks are finished successfully, async call the "master" callback with all errors and all...

async.waterfall(tasks, afterTasksCallback) will execute a set of tasks. Each task are executed after another, and the result of a task is passed to the next task. As async.series(), if a task fails, async stop the execution and call immediately the main callback. When tasks are finished successfull...

Dropping the database is a simple one-liner statement. Drop database will delete the database, hence always ensure to have a backup of the database if required. Below is the command to drop Employees Database DROP DATABASE [dbo].[Employees]

SELECT name, caption as title, year, pages FROM books UNION SELECT name, title, year, 0 as pages FROM movies When combining 2 record sets with different columns then emulate the missing ones with default values.

extern int var; static int var; /* Undefined behaviour */ C11, §6.2.2, 7 says: If, within a translation unit, the same identifier appears with both internal and external linkage, the behavior is undefined. Note that if an prior declaration of an identifier is visible then it'll have the pri...

Use the yum command to manage packages in Enterprise Linux-based operating systems: yum install php This installs a minimal install of PHP including some common features. If you need additional modules, you will need to install them separately. Once again, you can use yum to search for these pac...

Note: There will be some Objective-c in this example.. We will make a wrapper to C++ in this example, So don't worry to much about it. First start Xcode and create a project. And select a Cocoa application Delete all sources except the Info.plist file.(Your app won't work without it) Creat...

You can use the header() function to instruct the browser to redirect to a different URL: $url = 'https://example.org/foo/bar'; if (!headers_sent()) { // check headers - you can not send headers if they already sent header('Location: ' . $url); exit; // protects from code being executed afte...

git log --graph --pretty=format:'%C(red)%h%Creset -%C(yellow)%d%Creset %s %C(green)(%cr) %C(yellow)<%an>%Creset' The format option allows you to specify your own log output format: ParameterDetails%C(color_name)option colors the output that comes after it%h or %Habbreviates commit hash (us...

#include <Windows.h> DWORD WINAPI DoStuff(LPVOID lpParameter) { // The new thread will start here return 0; } int main() { // Create a new thread which will start at the DoStuff function HANDLE hThread = CreateThread( NULL, // Thread attributes ...

The easiest option to draw a circle, is - obviously - the rectangle function. %// radius r = 2; %// center c = [3 3]; pos = [c-r 2*r 2*r]; rectangle('Position',pos,'Curvature',[1 1]) axis equal but the curvature of the rectangle has to be set to 1! The position vector defines the rect...

Firstly, one can use quiver, where one doesn't have to deal with unhandy normalized figure units by use of annotation drawArrow = @(x,y) quiver( x(1),y(1),x(2)-x(1),y(2)-y(1),0 ) x1 = [10 30]; y1 = [10 30]; drawArrow(x1,y1); hold on x2 = [25 15]; y2 = [15 25]; drawArrow(x2,y2) ...

Improper Inheritance Lets say there are 2 classes class Foo and Bar. Foo has two features Do1 and Do2. Bar needs to use Do1 from Foo, but it doesn't need Do2 or needs feature that is equivalent to Do2 but does something completely different. Bad way: make Do2() on Foo virtual then override it in B...

C# developers get a lot of null reference exceptions to deal with. F# developers don't because they have the Option type. An Option<> type (some prefer Maybe<> as a name) provides a Some and a None return type. It makes it explicit that a method may be about to return a null record. For...

One of Angular's strength's is client-side form validation. Dealing with traditional form inputs and having to use interrogative jQuery-style processing can be time-consuming and finicky. Angular allows you to produce professional interactive forms relatively easily. The ng-model directive provide...

uses System.Character; var S1, S2: string; begin S1 := 'Foo'; S2 := ToLower(S1); // Convert the string to lower-case S1 := ToUpper(S2); // Convert the string to upper-case

2009 uses Character; var C1, C2: Char; begin C1 := 'F'; C2 := ToLower(C1); // Convert the char to lower-case C1 := ToUpper(C2); // Convert the char to upper-case The uses clause should be System.Character if version is XE2 or above.

The assignment operator = sets thr left hand operand's value to the value of right hand operand, and return that value: int a = 3; // assigns value 3 to variable a int b = a = 5; // first assigns value 5 to variable a, then does the same for variable b Console.WriteLine(a = 3 + 4); // prints ...

Sometimes you may need additional features from a directive. Instead of rewriting (copy) the directive, you can modify how the directive behaves. The decorator will be executed during $inject phase. To do so, provde a .config to your module. The directive is called myDirective, so you have to con...