Tutorial by Examples: ar

Passing arguments by reference or value

In JavaScript all arguments are passed by value. When a function assigns a new value to an argument variable, that change will not be visible to the caller: var obj = {a: 2}; function myfunc(arg){ arg = {a: 5}; // Note the assignment is to the parameter variable itself } myfunc(obj); conso...

JavaScript • Functions

Using ngStorage to share data

Firstly, include the ngStorage source in your index.html. An example injecting ngStorage src would be: <head> <title>Angular JS ngStorage</title> <script src = "http://ajax.googleapis.com/ajax/libs/angularjs/1.3.14/angular.min.js"></script> &l...

AngularJS • Sharing Data

Declaring permissions in your manifest file

Any permission required by your application to access a protected part of the API or to interact with other applications must be declared in your AndroidManifest.xml file. This is done using the <uses-permission /> tag. Syntax <uses-permission android:name="string" android...

Android • The Manifest File

Const local variables

Declaration and usage. // a is const int, so it can't be changed const int a = 15; a = 12; // Error: can't assign new value to const variable a += 1; // Error: can't assign new value to const variable Binding of references and pointers int &b = a; // Error: ca...

C++ • const keyword

Create Single Gift Card

// Instantiate Gift Card Model $gift_card = Mage::getModel('enterprise_giftcardaccount/giftcardaccount'); // Populate Gift Card values $gift_card // Your redeemable code, doesn't have to be in this format. ->setCode('2i2j2j-24k1ii1-67774k-231l') // Also has STATUS_DISABLED ...

magento • Create Enterprise Gift Cards Programmatically

Mistakenly writing = instead of == when comparing

The = operator is used for assignment. The == operator is used for comparison. One should be careful not to mix the two. Sometimes one mistakenly writes /* assign y to x */ if (x = y) { /* logic */ } when what was really wanted is: /* compare if x is equal to y */ if (x == y) { ...

C Language • Common pitfalls

Getting a shell into a running (detached) container

Log into a running container A user can enter a running container in a new interactive bash shell with exec command. Say a container is called jovial_morse then you can get an interactive, pseudo-TTY bash shell by running: docker exec -it jovial_morse bash Log into a running container with a s...

Docker • Running containers

Draw a red cross using l (relative line) path commands

SVG • Paths

Starting the server

Once Wildfly is installed by unzipping the distribution, it can be started by running the standalone.sh script on the bin directory: $ ./bin/standalone.sh ========================================================================= JBoss Bootstrap Environment JBOSS_HOME: /mnt/storage/tools...

wildfly • Getting started with wildfly

Inter-operating with Java reflection

To obtain a Java's Class object from Kotlin's KClass use the .java extension property: val stringKClass: KClass<String> = String::class val c1: Class<String> = stringKClass.java val c2: Class<MyClass> = MyClass::class.java The latter example will be optimized by the compile...

Kotlin • Reflection

Override merge/compare tools

Got to Tools | Options | Source Control | Visual Studio Team Foundation Server click on the Configure User Tools: You can add separate overrides for 'Compare' and 'Merge' operations. Click on Add and select the operation you want to override. You'd need to type the path to the tool you use, and ...

Visual Studio • Visual Studio tools

Leaked variables in list comprehension

Python 2.x2.3 x = 'hello world!' vowels = [x for x in 'AEIOU'] print (vowels) # Out: ['A', 'E', 'I', 'O', 'U'] print(x) # Out: 'U' Python 3.x3.0 x = 'hello world!' vowels = [x for x in 'AEIOU'] print (vowels) # Out: ['A', 'E', 'I', 'O', 'U'] print(x) # Out: 'hello world!' ...

Python Language • Incompatibilities moving from Python 2 to Python 3

ngBind (curly markup)

AngularJS code for rendering plain text: <p>{{ ScopePropertyX }} and {{ ScopePropertyY }}</p> KnockoutJS equivalent: <p>  and  </p> or: ...

knockout.js • Equivalents of AngularJS bindings

Laravel 5 App on Shared Hosting on Linux Server

By default Laravel project's public folder exposes the content of the app which can be requested from anywhere by anyone, the rest of the app code is invisible or inaccessible to anyone without proper permissions. After developing the application on your development machine, it needs to be pushed t...

Laravel • Deploy Laravel 5 App on Shared Hosting on Linux Server

Automatic package installation on emacs start-up

;; package.el is available since emacs 24 (require 'package) ;; Add melpa package source when using package list (add-to-list 'package-archives '("melpa" . "http://melpa.org/packages/") t) ;; Load emacs packages and activate them ;; This must come before configurations o...

emacs • Package Management

Using an uninitialized local variable

int a; std::cout << a; // Undefined behavior! This results in undefined behavior, because a is uninitialised. It is often, incorrectly, claimed that this is because the value is "indeterminate", or "whatever value was in that memory location before". However, it is th...

C++ • Undefined Behavior

Named Arguments

local function A(name, age, hobby) print(name .. "is " .. age .. " years old and likes " .. hobby) end A("john", "eating", 23) --> prints 'john is eating years old and likes 23' -- oops, seems we got the order of the arguments wrong... -- this happ...

Lua • Functions

Parsing with DCGs

DCGs can be used for parsing. Best of all, the same DCG can often be used to both parse and generate lists that are being described. For example: sentence --> article, subject, verb, object. article --> [the]. subject --> [woman] | [man]. verb --> [likes] | [enjoys]. object ...

Prolog Language • Definite Clause Grammars (DCGs)

Installing Elasticsearch on Ubuntu 14.04

Prerequisites In order to run Elasticsearch, a Java Runtime Environment (JRE) is required on the machine. Elasticsearch requires Java 7 or higher and recommends Oracle JDK version 1.8.0_73. Install Oracle Java 8 sudo add-apt-repository -y ppa:webupd8team/java sudo apt-get update echo "or...

Elasticsearch • Getting started with Elasticsearch

Access character at index in string

Use charAt() to get a character at the specified index in the string. var string = "Hello, World!"; console.log( string.charAt(4) ); // "o" Alternatively, because strings can be treated like arrays, use the index via bracket notation. var string = "Hello, World!";...

JavaScript • Strings