Tutorial by Examples: d

The ternary operator is used for inline conditional expressions. It is best used in simple, concise operations that are easily read. The order of the arguments is different from many other languages (such as C, Ruby, Java, etc.), which may lead to bugs when people unfamiliar with Python's "s...

A new thread separate from the main thread's execution, can be created using Thread.new. thr = Thread.new { sleep 1 # 1 second sleep of sub thread puts "Whats the big deal" } This will automatically start the execution of the new thread. To freeze execution of the main Thread, ...

Python 2.x2.3 Objects of different types can be compared. The results are arbitrary, but consistent. They are ordered such that None is less than anything else, numeric types are smaller than non-numeric types, and everything else is ordered lexicographically by type. Thus, an int is less than a st...

def say_hello_to(name) puts "Hello #{name}" end say_hello_to('Charles') # Hello Charles

def greet(greeting, name) puts "#{greeting} #{name}" end greet('Hi', 'Sophie') # Hi Sophie

def make_animal_sound(sound = 'Cuack') puts sound end make_animal_sound('Mooo') # Mooo make_animal_sound # Cuack It's possible to include defaults for multiple arguments: def make_animal_sound(sound = 'Cuack', volume = 11) play_sound(sound, volume) end make_animal_so...

Let's say we have an interface for logging: interface Logger { function log($message); } Now say we have two concrete implementations of the Logger interface: the FileLogger and the ConsoleLogger. class FileLogger implements Logger { public function log($message) { // Append...

Basic usage: PropertyInfo prop = myInstance.GetType().GetProperty("myProperty"); // get the value myInstance.myProperty object value = prop.GetValue(myInstance); int newValue = 1; // set the value myInstance.myProperty to newValue prop.setValue(myInstance, newValue); Setting rea...

SQLiteOpenHelper is a helper class to manage database creation and version management. In this class, the onUpgrade() method is responsible for upgrading the database when you make changes to the schema. It is called when the database file already exists, but its version is lower than the one spec...

While static constructors are always called before the first usage of a type it's sometimes useful to be able to force them to be called and the RuntimeHelpers class provide an helper for it: using System.Runtime.CompilerServices; // ... RuntimeHelpers.RunClassConstructor(typeof(Foo).TypeHand...

This example use the default boxplot() function and the irisdata frame. > head(iris) Sepal.Length Sepal.Width Petal.Length Petal.Width Species 1 5.1 3.5 1.4 0.2 setosa 2 4.9 3.0 1.4 0.2 setosa 3 4.7 3.2 ...

ALTER TABLE Employees DROP CONSTRAINT DefaultSalary This Drops a constraint called DefaultSalary from the employees table definition. Note:- Ensure that constraints of the column are dropped before dropping a column.

ALTER TABLE Employees ADD CONSTRAINT DefaultSalary DEFAULT ((100)) FOR [Salary] This adds a constraint called DefaultSalary which specifies a default of 100 for the Salary column. A constraint can be added at the table level. Types of constraints Primary Key - prevents a duplicate record in...

The Clojure community puts a large emphasis on interactive development, so quite a lot of interaction with Clojure happens within a REPL (read-eval-print-loop). When you input an expression into it, Clojure reads it, evaluates it, and prints the result of the evaluation, all in a loop. You should b...

For installation instructions on elixir check here, it describes instructions related to different platforms. Elixir is a programming language that is created using erlang, and uses erlang's BEAM runtime (like JVM for java). We can use elixir in two modes: interactive shell iex or directly running...

Enums can define abstract methods, which each enum member is required to implement. enum Action { DODGE { public boolean execute(Player player) { return player.isAttacking(); } }, ATTACK { public boolean execute(Player player) { re...

Setting a default value can be done by using Initializers (C#6) public class Name { public string First { get; set; } = "James"; public string Last { get; set; } = "Smith"; } If it is read only you can return values like this: public class Name { pu...

The function is_array() returns true if a variable is an array. $integer = 1337; $array = [1337, 42]; is_array($integer); // false is_array($array); // true You can type hint the array type in a function to enforce a parameter type; passing anything else will result in a fatal error. funct...

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slice1 := []string{"!"} slice2 := []string{"Hello", "world"} slice := append(slice1, slice2...) Run in the Go Playground