Tutorial by Examples: od

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...

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...

UIDatePicker has various picker modes. enum UIDatePickerMode : Int { case Time case Date case DateAndTime case CountDownTimer } Time - The date picker displays hours, minutes, and (optionally) an AM/PM designation. Date - The date picker displays months, days of the mon...

Let's say you have a library that returns callbacks, for example the fs module in NodeJS: const fs = require("fs"); fs.readFile("/foo.txt", (err, data) => { if(err) throw err; console.log(data); }); We want to convert it to a promise returning API, with bluebird - ...

You can convert a single function with a callback argument to a Promise-returning version with Promise.promisify, so this: const fs = require("fs"); fs.readFile("foo.txt", (err, data) => { if(err) throw err; console.log(data); }); becomes: const promisify = requ...

When signing personal scripts or when testing code signing it can be useful to create a self-signed code signing certificate. 5.0 Beginning with PowerShell 5.0 you can generate a self-signed code signing certificate by using the New-SelfSignedCertificate-cmdlet: New-SelfSignedCertificate -Friendl...

If you are only adding new rows in your RDBMS (not updating existing data) You need two additional parameters: --check-column : A column name that should be checked for newly appended data. Integer would be a suitable data type for this column. --last-value : The last value that successfully im...

If you are adding new rows and updating existing data. You need two additional parameters: --check-column : A column name that should be checked for newly appended and updated data. date, time, datetime and timestamp are suitable data types for this column. --last-value : The last value that su...

'use strict'; const http = require('http'); const PORT = 8080; const server = http.createServer((request, response) => { let buffer = ''; request.on('data', chunk => { buffer += chunk; }); request.on('end', () => { const responseString = `Received string ${buffe...

Data_1 = [<<"Hello">>]. Data_2 = [Data_1,<<" Guten Tag ">>].

On StackOverflow, we often see code like this in Answers: public String joinStrings(String a, String b) { if (a == null) { a = ""; } if (b == null) { b = ""; } return a + ": " + b; } Often, this is accompanied with an asse...

Utilizing .Net System.Security.Cryptography.HashAlgorithm namespace to generate the message hash code with the algorithms supported. $example="Nobody expects the Spanish Inquisition." #calculate $hash=[System.Security.Cryptography.HashAlgorithm]::Create("sha256").ComputeHas...

Most Rails developers start by modifying their model information within the template itself: <h1><%= "#{ @user.first_name } #{ @user.last_name }" %></h1> <h3>joined: <%= @user.created_at.in_time_zone(current_user.timezone).strftime("%A, %d %b %Y %l:%M %p&q...

DateTime + Fixnum (days quantity) DateTime.new(2015,12,30,23,0) + 1 # => #<DateTime: 2015-12-31T23:00:00+00:00 ((2457388j,82800s,0n),+0s,2299161j)> DateTime + Float (days quantity) DateTime.new(2015,12,30,23,0) + 2.5 # => #<DateTime: 2016-01-02T11:00:00+00:00 ((2457390j,39600s,...

You can realize a modal bottom sheets using a BottomSheetDialogFragment. The BottomSheetDialogFragment is a modal bottom sheet. This is a version of DialogFragment that shows a bottom sheet using BottomSheetDialog instead of a floating dialog. Just define the fragment: public class MyBottomSheet...

The BottomSheetDialog is a dialog styled as a bottom sheet Just use: //Create a new BottomSheetDialog BottomSheetDialog dialog = new BottomSheetDialog(context); //Inflate the layout R.layout.my_dialog_layout dialog.setContentView(R.layout.my_dialog_layout); //Show the dialog dialog.show(); ...

C# 7.0 adds accessors, constructors and finalizers to the list of things that can have expression bodies: class Person { private static ConcurrentDictionary<int, string> names = new ConcurrentDictionary<int, string>(); private int id = GetId(); public Person(string n...

This is useful if you use rust in the backend and elm on the front end enum Complex{ Message(String), Size(u64) } let c1 = Complex::Message("hi"); let c2 = Complex::Size(1024u64); The encoded Json from rust will be: c1: {"variant": "Message", ...

A chrome extension is seperated into a maximum of 4 parts: the background page the popup page one or more content scripts the options page Each part, since they are innately separate, require individual debugging. Keep in mind that these pages are separate, meaning that variables are not d...

Trees are a sub-type of the more general node-edge graph data structure. To be a tree, a graph must satisfy two requirements: It is acyclic. It contains no cycles (or "loops"). It is connected. For any given node in the graph, every node is reachable. All nodes are reachable throug...