Tutorial by Examples: d

In Kotlin, classes are final by default which means they cannot be inherited from. To allow inheritance on a class, use the open keyword. open class Thing { // I can now be extended! } Note: abstract classes, sealed classes and interfaces will be open by default.

Defining the base class: open class BaseClass { val x = 10 } Defining the derived class: class DerivedClass: BaseClass() { fun foo() { println("x is equal to " + x) } } Using the subclass: fun main(args: Array<String>) { val derivedClass = Deri...

Defining the base class: open class Person { fun jump() { println("Jumping...") } } Defining the derived class: class Ninja: Person() { fun sneak() { println("Sneaking around...") } } The Ninja has access to all of the methods in Pe...

Sometimes your webpage needs a automatic redirect. For example, to redirect to example.com after 5 seconds: <meta http-equiv="refresh" content="5;url=https://www.example.com/" /> This is line will send you to the designated website (in this case example.com after 5 sec...

setuptools_scm is an officially-blessed package that can use Git or Mercurial metadata to determine the version number of your package, and find Python packages and package data to include in it. from setuptools import setup, find_packages setup( setup_requires=['setuptools_scm'], use_...

PostScript is a Turing-complete general programming language, designed and developed by Adobe Systems. Many of the ideas which blossomed in PostScript had been cultivated in projects for Xerox and Evans & Sutherland. Its main real-world application historically is as a page description language...

def hello_world(greeting: str = 'Hello'): print(greeting + ' world!') Note the spaces around the equal sign as opposed to how keyword arguments are usually styled.

CREATE TABLE menagerie.bird ( bird_id INT NOT NULL AUTO_INCREMENT, species VARCHAR(300) DEFAULT NULL COMMENT 'You can include genus, but never subspecies.', INDEX idx_species (species) COMMENT 'We must search on species often.', PRIMARY KEY (bird_id) ) ENGINE=InnoDB COMMENT 'Thi...

Bit-fields give an ability to declare structure fields that are smaller than the character width. Bit-fields are implemented with byte-level or word-level mask. The following example results in a structure of 8 bytes. struct C { short s; /* 2 bytes */ char c; /* 1 ...

Emacs' documentation uses a consistent notation for all key bindings, which is explained here: Key chords A "key chord" is obtained by pressing two or more keys simultaneously. Key chords are denoted by separating all keys by dashes (-). They usually involve modifier keys, which are put ...

Create example table Employee: CREATE TABLE Employee ( Id INT, EmpName VARCHAR(25), EmpGender VARCHAR(6), EmpDeptId INT ) Creates stored procedure that checks whether the values passed in stored procedure are not null or non empty and perform insert operation in Employee ta...

Open a Command Prompt window and run the following commands: adb kill-server set ADB_TRACE=sockets adb nodaemon server 2>&1 | for /f "usebackq tokens=7*" %a in (`findstr /c:"): '"`) do @echo %a %b >> %USERPROFILE%\Desktop\adb_host_log.txt Now you can run your A...

php bin/magento setup:upgrade

IIS / .NET version Requirements: See here SignalR 2+ Install the NuGet package Microsoft.AspNet.SignalR (this is the whole SignalR solution) and it will ask you to install any dependencies for other packages. Accept the terms and install them as well. Now that we've got the .dlls and clie...

You can see list with all environment variables with: Get-Childitem env:

4.0 #requires -RunAsAdministrator After trying to run this script without admin privileges, you will see this error message .\script.ps1 : The script 'script.ps1' cannot be run because it contains a "#requires" statement for running as Administrator. The current Windows PowerShell s...

The Java programming language (and its runtime) has undergone numerous changes since its release since its initial public release. These changes include: Changes in the Java programming language syntax and semantics Changes in the APIs provided by the Java standard class libraries. Changes in ...

Every Python statement in Vim should be prefixed with the :python command, to instruct Vim that the next command is not Vimscript but Python. To avoid typing this command on each line, when executing multi-line Python code, it is possible to instruct Vim to interpret the code between two marker exp...

In order to begin using WebRTC you need to get camera and microphone permission.For that you need following things: adapter.js, you can get it from here A html webpage with a video tag and little bit of js code The adapter.js is a JavaScript shim for WebRTC, maintained by Google with help fro...

Paste this code into an empty HTML file and run it in your browser. <!DOCTYPE html> <body> <script src="https://d3js.org/d3.v4.js"></script> <!-- This downloads d3 library --> <script> //This code will visualize a data set as a simple scatt...