Tutorial by Examples: b

Using a base template

base.twig.html <!DOCTYPE html> <html> <head> <title>{{ title | default('Hello World') }}</title> <link rel="stylesheet" type="text/css" href="theme.css"> {% block css %} {% endblock %} &...

twig • Template inheritance

The dir() function can be used to get a list of the members of a class: dir(Class) For example: >>> dir(list) ['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__...

Python Language • Classes

Remove Whitespace from the Beginning and End of a String

The trim() method returns a new String with the leading and trailing whitespace removed. String s = new String(" Hello World!! "); String t = s.trim(); // t = "Hello World!!" If you trim a String that doesn't have any whitespace to remove, you will be returned the same S...

Java Language • Strings

Private key is not accepted (OpenSSH clients debug)

By default, most of the information is hidden from the user. You can use -v switches to get a verbose log of the connection attempt, which will usually pinpoint the problem by showing why the behavior is different than you expect. Let's assume you are connecting to the server example.com using ssh ...

Secure Shell • Debugging ssh problems

DESCRIBE tablename;

DESCRIBE and EXPLAIN are synonyms. DESCRIBE on a tablename returns the definition of the columns. DESCRIBE tablename; Exmple Result: COLUMN_NAME COLUMN_TYPE IS_NULLABLE COLUMN_KEY COLUMN_DEFAULT EXTRA id int(11) NO PRI 0 ...

SQL • EXPLAIN and DESCRIBE

How to configure the build.gradle file

android { ... defaultConfig {...} buildTypes {...} productFlavors { demo { applicationId "com.example.myapp.demo" versionName "1.0-demo" } full { applicationId "com.example.myapp.full"...

android-gradle • Configure Product Flavors

Countries Table

In this example, we have a Countries table. A table for countries has many uses, especially in Financial applications involving currencies and exchange rates. Live example: SQL fiddle Some Market data software applications like Bloomberg and Reuters require you to give their API either a 2 or 3 ch...

SQL • Example Databases and Tables

Add a Customizer Section With Basic Settings and their Controls

Panels can have sections, sections can have settings, and settings can have controls. Settings are saved in the database, while the controls for particular settings are only used to display their corresponding setting to the user. This code creates a basic section in the panel from above. Inside a...

WordPress • Customizer Basics (Add Panel, Section, Setting, Control)

Include definition file with library on npm

Add typings to your package.json { ... "typings": "path/file.d.ts" ... } Now when ever that library is imported typescript will load the typings file

TypeScript • Publish TypeScript definition files

Removing the Admin Toolbar from all except Administrators

Add the following code to functions.php to remove it from everyone except the Administrator user level: add_action('after_setup_theme', 'no_admin_bar'); function no_admin_bar() { if (!current_user_can('administrator') && !is_admin()) { show_admin_bar(false); ...

WordPress • The Admin Bar (aka "The Toolbar")

Create a new Rails app with a non-standard database adapter

Rails is shipped by default with ActiveRecord, an ORM (Object Relational Mapping) derived from the pattern with the same name. As an ORM, it is built to handle relational-mapping, and more precisely by handling SQL requests for you, hence the limitation to SQL databases only. However, you can stil...

Ruby on Rails • Getting started with Ruby on Rails

Installing Global Packages

Install a global package Globally installed packages drops modules in {prefix}/lib/node_modules, and puts executable files in {prefix}/bin, where {prefix} is usually something like /usr/local. Installing a global module means that its binaries end up in your PATH environment variable. Usually you'l...

npm • Getting started with npm

Math using bc

bc is an arbitrary precision calculator language. It could be used interactively or be executed from command line. For example, it can print out the result of an expression: echo '2 + 3' | bc 5 echo '12 / 5' | bc 2 For floating-post arithmetic, you can import standard library bc -l: echo ...

Bash • Math

Basic unit test example

This example is a basic setup for unittesting the StringBuilder.toString() using junit. import static org.junit.Assert.assertEquals; import org.junit.Test; public class StringBuilderTest { @Test public void stringBuilderAppendShouldConcatinate() { StringBuilder stringBui...

junit • Getting started with junit

Attaching a Method to a Button

To add a method to a button, first create an action method: Objective-C -(void) someButtonAction{ NSLog(@"Button is tapped"); } Swift func someButtonAction() { print("Button is tapped") } Now to add this action method to your button, you have to wri...

iOS • UIButton

Use Trigger to manage a "Recycle Bin" for deleted items

CREATE TRIGGER BooksDeleteTrigger ON MyBooksDB.Books AFTER DELETE AS INSERT INTO BooksRecycleBin SELECT * FROM deleted; GO

SQL • Triggers

Basic usage of Async/Await

You can start some slow process in parallel and then collect the results when they are done: Public Sub Main() Dim results = Task.WhenAll(SlowCalculation, AnotherSlowCalculation).Result For Each result In results Console.WriteLine(result) Next End Sub Async Functio...

Visual Basic .NET Language • Task-based asynchronous pattern

Copy to clipboard from textarea using execCommand("copy")

Example: <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title></title> </head> <body> <textarea id="content"></textarea> <input type="button" id="copy...

JavaScript • execCommand and contenteditable

Character class and common problems faced by beginner

1. Character Class Character class is denoted by []. Content inside a character class is treated as single character separately. e.g. suppose we use [12345] In the example above, it means match 1 or 2 or 3 or 4 or 5 . In simple words, it can be understood as or condition for single characters (...

Regular Expressions • Character classes

Block with

The blockquote element can be used for a (block-level) quote: <blockquote> <p>The answer is 42.</p> </blockquote> Source URL (cite attribute) The cite attribute can be used to reference the URL of the quoted source: <blockquote cite="http://example.com/blog/...

HTML • Marking-up Quotes