Tutorial by Examples: r

Imports System.Reflection Public Class PropertyExample Public Function GetMyProperties() As PropertyInfo() Dim objProperties As PropertyInfo() objProperties = Me.GetType.GetProperties(BindingFlags.Public Or BindingFlags.Instance) Return objProperties End Fun...

As Handlers are used to send Messages and Runnables to a Thread's message queue it's easy to implement event based communication between multiple Threads. Every Thread that has a Looper is able to receive and process messages. A HandlerThread is a Thread that implements such a Looper, for example th...

Naming Convention Notifications are identified by global NSString objects whose names are composed in this way: Name of associated class + Did | Will + UniquePartOfName + Notification For example: NSApplicationDidBecomeActiveNotification NSWindowDidMiniaturizeNotification NSTextViewDidChange...

Swift 2.3 //Remove observer for single notification NSNotificationCenter.defaultCenter().removeObserver(self, name: "TestNotification", object: nil) //Remove observer for all notifications NotificationCenter.defaultCenter().removeObserver(self) Swift 3 //Remove observer for s...

Swift func testNotification(notification: NSNotification) { let userInfo = notification.userInfo let myObject: MyObject = userInfo["someKey"] } Objective-C - (void)testNotification:(NSNotification *)notification { NSDictionary *userInfo = notification.userInfo; My...

iex(1)> i :ok Term :ok Data type Atom Reference modules Atom iex(2)> x = "mystring" "mystring" iex(3)> i x Term "mystring" Data type BitString Byte size 8 Description This is a string: a UTF-8 encoded binary. It's printed surround...

#You can use pattern matching to run different #functions based on which parameters you pass #This example uses pattern matching to start, #run, and end a recursive function defmodule Counter do def count_to do count_to(100, 0) #No argument, init with 100 end def ...

Syntax: REPLACE( String to search , String to search for and replace , String to place into the original string ) Example: SELECT REPLACE( 'Peter Steve Tom', 'Steve', 'Billy' ) --Return Values: Peter Billy Tom

Creating a DB and a Table DROP DATABASE IF EXISTS books_db; CREATE DATABASE books_db WITH ENCODING='UTF8' TEMPLATE template0; DROP TABLE IF EXISTS books; CREATE TABLE books ( id SERIAL PRIMARY KEY, client TEXT NOT NULL, data JSONb NOT NULL ); Populating the DB INSERT INTO books...

p { margin:1px; /* 1px margin in all directions */ /*equals to:*/ margin:1px 1px; /*equals to:*/ margin:1px 1px 1px; /*equals to:*/ margin:1px 1px 1px 1px; } Another exapmle: p{ margin:10px 15px; /...

g$ The above matches one letter (the letter g) at the end of a string in most regex engines (not in Oniguruma, where the $ anchor matches the end of a line by default, and the m (MULTILINE) modifier is used to make a . match any characters including line break characters, as a DOTALL modifier in ...

my $filename = '/path/to/file'; open my $fh, '<', $filename or die "Failed to open file: $filename"; # You can then either read the file one line at a time... while(chomp(my $line = <$fh>)) { print $line . "\n"; } # ...or read whole file into an arra...

You can use subqueries to define a temporary table and use it in the FROM clause of an "outer" query. SELECT * FROM (SELECT city, temp_hi - temp_lo AS temp_var FROM weather) AS w WHERE temp_var > 20; The above finds cities from the weather table whose daily temperature variation i...

The following example finds cities (from the cities example) whose population is below the average temperature (obtained via a sub-qquery): SELECT name, pop2000 FROM cities WHERE pop2000 < (SELECT avg(pop2000) FROM cities); Here: the subquery (SELECT avg(pop2000) FROM cities) is used to s...

Subqueries can also be used in the SELECT part of the outer query. The following query shows all weather table columns with the corresponding states from the cities table. SELECT w.*, (SELECT c.state FROM cities AS c WHERE c.name = w.city ) AS state FROM weather AS w;

Ember CLI allows you to use one of two options to generate a new app: Create a folder and run ember init (generates application structure and sets up git and makes your first commit) Run ember new <app name> (creates a folder with the specified name, steps into it and runs ember init) O...

Elixir doesn't have loops. Instead of them for lists there are great Enum and List modules, but there are also List Comprehensions. List Comprehensions can be useful to: create new lists iex(1)> for value <- [1, 2, 3], do: value + 1 [2, 3, 4] filtering lists, using guard expressi...

NSArray *reversedArray = [myArray.reverseObjectEnumerator allObjects];

Maps are the Elixir key-value (also called dictionary or hash in other languages) type. You create a map using the %w{} syntax: %{} // creates an empty map %{:a => 1, :b => 2} // creates a non-empty map Keys and values can use be any type: %{"a" => 1, "b" => 2} ...

This is useful when you didn't store the PID from a previous command iex(1)> self() #PID<0.138.0> iex(2)> pid("0.138.0") #PID<0.138.0> iex(3)> pid(0, 138, 0) #PID<0.138.0>