Tutorial by Examples: r

You can write the default protocol implementation for a specific class. protocol MyProtocol { func doSomething() } extension MyProtocol where Self: UIViewController { func doSomething() { print("UIViewController default protocol implementation") } } class M...

Generic classes can be inherited: // Models class MyFirstModel { } class MySecondModel: MyFirstModel { } // Generic classes class MyFirstGenericClass<T: MyFirstModel> { func doSomethingWithModel(model: T) { // Do something here } } class MySecondGe...

Setting up settings.py from django.utils.translation import ugettext_lazy as _ USE_I18N = True # Enable Internationalization LANGUAGE_CODE = 'en' # Language in which original texts are written LANGUAGES = [ # Available languages ('en', _("English")), ('de', _("Germ...

In order to efficiently handle cycle detection, we consider each node as part of a tree. When adding an edge, we check if its two component nodes are part of distinct trees. Initially, each node makes up a one-node tree. algorithm kruskalMST'(G: a graph) sort G's edges by their value MST ...

The DOM (Document Object Model) is the programming interface for HTML and XML documents, it defines the logical structure of documents and the way a document is accessed and manipulated. The main implementers of the DOM API are web browsers. Specifications are standardized by the W3C and the WHATW...

ceil() The ceil() method rounds a number upwards to the nearest integer, and returns the result. Syntax: Math.ceil(n); Example: console.log(Math.ceil(0.60)); // 1 console.log(Math.ceil(0.40)); // 1 console.log(Math.ceil(5.1)); // 6 console.log(Math.ceil(-5.1)); // -5 console.log(Math....

JSON stands for "JavaScript Object Notation", but it's not JavaScript. Think of it as just a data serialization format that happens to be directly usable as a JavaScript literal. However, it is not advisable to directly run (i.e. through eval()) JSON that is fetched from an external source...

1. Target a device by serial number Use the -s option followed by a device name to select on which device the adb command should run. The -s options should be first in line, before the command. adb -s <device> <command> Example: adb devices List of devices attached emulator-55...

Each requirements files should match the name of a settings files. Read Using multiple settings for more information. Structure djangoproject ├── config │ ├── __init__.py │ ├── requirements │ │ ├── base.txt │ │ ├── dev.txt │ │ ├── test.txt │ │ └── prod.txt │ └── setti...

using (new Sitecore.SecurityModel.SecurityDisabler()) { var item = Sitecore.Context.Database.GetItem("/sitecore/content/home"); }

var user = Sitecore.Security.Accounts.User.FromName("sitecore/testname", false); using (new Sitecore.Security.Accounts.UserSwitcher(user)) { var item = Sitecore.Context.Database.GetItem("/sitecore/content/home"); }

NSError *e = nil; NSString *jsonString = @"[{\"id\": \"1\", \"name\":\"sam\"}]"; NSData *data = [jsonString dataUsingEncoding:NSUTF8StringEncoding]; NSArray *jsonArray = [NSJSONSerialization JSONObjectWithData: data options: NSJSONReadingMutabl...

Just like in case of the function arguments, template parameters can have their default values. All template parameters with a default value have to be declared at the end of the template parameter list. The basic idea is that the template parameters with default value can be omitted while template ...

Useful if your program is outputting web pages along the way. from http.server import HTTPServer, CGIHTTPRequestHandler import webbrowser import threading def start_server(path, port=8000): '''Start a simple webserver serving path on port''' os.chdir(path) httpd = HTTPServer((''...

When you create an argparse ArgumentParser() and run your program with '-h' you get an automated usage message explaining what arguments you can run your software with. By default, positional arguments and conditional arguments are separated into two categories, for example, here is a small script ...

The main app file loads the routes file where routes are defined. app.js var express = require('express'); var app = express(); app.use('/', require('./routes')); app.listen('3000'); routes.js var router = require('express').Router(); router.get('/', function(req, res) { res.sen...

Middleware is executed prior to the route execution and can decide whether to execute the router according to the URL. var router = require('express').Router(); router.use(function (req, res, next) { var weekDay = new Date().getDay(); if (weekDay === 0) { res.send('Web is clos...

Rust's #[path] attribute can be used to specify the path to search for a particular module if it is not in the standard location. This is typically discouraged, however, because it makes the module hierarchy fragile and makes it easy to break the build by moving a file in a completely different dire...

Often times you will see an exception Anti forgery token is meant for user "" but the current user is "username" This is because the Anti-Forgery token is also linked to the current logged-in user. This error appears when a user logs in but their token is still linked to bein...

String to a primitive numeric type or a numeric wrapper type: Each numeric wrapper class provides a parseXxx method that converts a String to the corresponding primitive type. The following code converts a String to an int using the Integer.parseInt method: String string = "59"; int p...