Tutorial by Examples: e

Use the double negation syntax to check for truthiness of values. All values correspond to a boolean, irrespective of their type. irb(main):001:0> !!1234 => true irb(main):002:0> !!"Hello, world!" (irb):2: warning: string literal in condition => true irb(main):003:0> !...

You do not need to use double negation in if-else statements. if 'hello' puts 'hey!' else puts 'bye!' end The above code prints 'hey!' on the screen.

If you can say “YAGNI” (You ain’t gonna need it) about a feature, you better not implement it. There can be a lot of development time saved through focussing onto simplicity. Implementing such features anyway can lead to problems: Problems Overengineering If a product is more complicated than it...

Lets you compose several functions f₀ f₁ … fₙ. It returns a function that will successively apply fₙ to its arguments, then fₙ₋₁ to the result of fₙ and so on. Function are applied from right to left, like for mathematical function composition: (f ∘ g ∘ h)(x) = f(g(h(x))). > ((compose sqrt +) 16...

Your app can't access your reminders and your calendar without permission. Instead, it must show an alert to user, requesting him/her to grant access to events for the app. To get started, import the EventKit framework: Swift import EventKit Objective-C #import <EventKit/EventKit.h> ...

Accessing the array of calendars To access the array of EKCalendars, we use the calendarsForEntityType method: Swift let calendarsArray = eventStore.calendarsForEntityType(EKEntityType.Event) as! [EKCalendar] Iterating through calendars Just use a simple for loop: Swift for calendar in cale...

Creating the event object Swift var event = EKEvent(eventStore: eventStore) Objective-C EKEvent *event = [EKEvent initWithEventStore:eventStore]; Setting related calendar, title and dates Swift event.calendar = calendar event.title = "Event Title" event.startDate = startDate /...

In Symfony, the built-in ChoiceType (and EntityType or DocumentType extending it), basicaly work with a constant choice list. If you want to make it work with ajax calls, you have to change them to accept any sumitted extra choices. How to start with an empty choice list ? When you build your...

This is an example to show how to change the allowed choices on a subCategory select field depending on the value of the category select field. To do that you have to make your subCategory choices dynamical for both client and server side. 1. Make the form dynamic on the client side for display / ...

In Ruby, there is always an implicit receiver for all method calls. The language keeps a reference to the current implicit receiver stored in the variable self. Certain language keywords like class and module will change what self points to. Understanding these behaviors is very helpful in mastering...

When you define a class or module, the implicit receiver becomes a reference to the class itself. For example: puts "I am #{self}" class Example puts "I am #{self}" end Executing the above code will print: "I am main" "I am Example"

Most Ruby code utilizes the implicit receiver, so programmers who are new to Ruby are often confused about when to use self. The practical answer is that self is used in two major ways: 1. To change the receiver. Ordinarily the behavior of def inside a class or module is to create instance methods...

Qt provides a deployment tool for Windows: windeployqt. The tool inspects a Qt application executable for its dependecies to Qt modules and creates a deployment directory with the necessary Qt files to run the inspected executable. A possible script may look like: set PATH=%PATH%;<qt_install_pre...

Setup variables JUSERID=$[ ( $RANDOM % 100 ) + 1 ] JUSERNAME="admin" JUSEREMAIL="[email protected]" JUSERPASS="qweasd" DB="joomla_3" DBUSER="jdbuser" DBPASS="dbupass" DBPREFIX="prfx_" JOOMLAVERSION="3.6.2" ...

BEGIN TRY -- start error handling BEGIN TRANSACTION; -- from here on transactions (modifictions) are not final -- start your statement(s) select 42/0 as ANSWER -- simple SQL Query with an error -- end your statement(s) COMMIT TRANSACTION; -- finalize all transa...

$basic_post_args = array( 'post_title' => 'My Basic Post', 'post_content' => 'This is a basic content', 'post_status' => 'publish', 'post_author' => 1, 'post_category' => array(8, 59) ); wp_insert_post( $basic_post_args );

$basic_page_args = array( 'post_title' => 'My Basic Page', 'post_content' => 'This is a basic content', 'post_type' => 'page', 'post_status' => 'publish', 'post_author' => 1 ); wp_insert_post( $basic_page_args );

The first thing we need is to tell karma to use Webpack to read our tests, under a configuration we set for the webpack engine. Here, I am using babel because I write my code in ES6, you can change that for other flavors, such as Typescript. Or I use Pug (formerly Jade) templates, you don't have to....

This returns the currently active spreadsheet, or null if there is none. var currentSheet = SpreadsheetApp.getActive(); var url = currentSheet.getUrl(); Logger.log( url );

Getting a reference to the main bundle using Cocoa. To get the main bundle in Cocoa application, call the mainBundle class method of the NSBundle class. NSBundle *mainBundle; // Get the main bundle for the app; mainBundle = [NSBundle mainBundle]; Getting a reference to ...