Tutorial by Examples: d

Ruby has three types of objects: Classes and modules which are instances of class Class or class Module. Instances of classes. Singleton Classes. Each object has a class which contains its methods: class Example end object = Example.new object.class # => Example Example.class # ...

In Normal, type the following to delete a range of lines into a named register :10,20d a This will delete lines 10,20 in register "a. We can verify this by typing :reg This will show the text that was delete in register "a. To paste the contents in "a, just type "ap ...

The canvas can be used to display video from a variety of sources. This example shows how to load a video as a file resource, display it and add a simple click on screen play/pause toggle. This stackoverflow self answered question How do I display a video using HTML5 canvas tag shows the following ...

A common mistake seen in JavaScript when run in a browser environment is updating the DOM more often than necessary. The issue here is that every update in the DOM interface causes the browser to re-render the screen. If an update changes the layout of an element in the page, the entire page layout...

Default date format: "mm/dd/yy" The following example shows how you can set the date format in initialization with the dateFormat option. <input type="text" id="datepicker"> <script> $("#datepicker").datepicker({ dateFormat: "...

Prerequisites Create a new project and add an iOS app to that project in the Firebase Console. Download and include GoogleServices-Info.plist in your application. Add Firebase Storage to your app Add the following dependency to your project's Podfile: pod 'Firebase/Storage' Run pod insta...

In assignments, you can split an Iterable into values using the "unpacking" syntax: Destructuring as values a, b = (1, 2) print(a) # Prints: 1 print(b) # Prints: 2 If you try to unpack more than the length of the iterable, you'll get an error: a, b, c = [1] # Raises: ValueError:...

Since Laravel version 5.2.31 the web middleware is applied by default within the RouteServiceProvider (https://github.com/laravel/laravel/commit/5c30c98db96459b4cc878d085490e4677b0b67ed) In app/Providers/RouteServiceProvider.php you will find the following functions which apply the middleware on ev...

To open a new window, add the following code somewhere where you can keep a reference to the new window (I.E., the app delegate). Swift let storyboard:NSStoryboard = NSStoryboard(name: "Main", bundle: nil) guard let controller:NSWindowController = storyboard.instantiateControllerWithIde...

The following example shows how you can use the pushd command and the popd command in a batch program to change the current directory from the one in which the batch program was run and then change it back: @echo off rem This batch file deletes all .txt files in a specified directory pushd %1 ...

To print the directory stack, use the command pushd without any parameters: @echo off cd C:\example\ pushd one pushd ..\two pushd ..\.. pushd echo Current Directory: %cd% echo: popd pushd three pushd echo Current Directory: %cd% Output: C:\example\two ...

with Ada.Text_IO; procedure Hello_World is begin Ada.Text_IO.Put_Line ("Hello World"); end Hello_World; Alternatively, after importing the package Ada.Text_IO, you can say use Ada.Text_IO; in order to be able to use Put_Line without explicitly declaring what package it should c...

It is unlikely for a developer to not come across a deprecated API during a development process. A deprecated program element is one that programmers are discouraged from using, typically because it is dangerous, or because a better alternative exists. Compilers and analyzers (like LINT) warn when a...

This is a huge topic, but it is also the most important "performance" issue. The main lesson for a novice is to learn of "composite" indexes. Here's a quick example: INDEX(last_name, first_name) is excellent for these: WHERE last_name = '...' WHERE first_name = '...' AND ...

x IN ( SELECT ... ) turn into a JOIN When possible, avoid OR. Do not 'hide' an indexed column in a function, such as WHERE DATE(x) = ...; reformulate as WHERE x = ... You can generally avoid WHERE LCASE(name1) = LCASE(name2) by having a suitable collation. Do no use OFFSET for "paginatio...

You can find the Chef documentation at https://docs.chef.io/.

Example below shows how to create a BroadcastReceiver which is able to receive BOOT_COMPLETED events. This way, you are able to start a Service or start an Activity as soon device was powered up. Also, you can use BOOT_COMPLETED events to restore your alarms since they are destroyed when device is ...

For the sake of this example, let us assume that we have a server for handling the POST requests that we will be making from our Android app: // User input data. String email = "[email protected]"; String password = "123"; // Our server URL for handling POST requests. String UR...

Casting: The Basics Casting is used to transform data from long to wide format. Starting with a long data set: DT = data.table(ID = rep(letters[1:3],3), Age = rep(20:22,3), Test = rep(c("OB_A","OB_B","OB_C"), each = 3), Result = 1:9) We can cast our data using the...

Defined in header <numeric> template<class InputIterator, class T> T accumulate(InputIterator first, InputIterator last, T init); // (1) template<class InputIterator, class T, class BinaryOperation> T accumulate(InputIterator first, InputIterator last, T init, BinaryOperation...