Tutorial by Examples: s

Each gem has a file in the format of <gem name>.gemspec which contains metadata about the gem and it's files. The format of a gemspec is as follows: Gem::Specification.new do |s| # Details about gem. They are added in the format: s.<detail name> = <detail value> end The ...

MY_CONSTANT = "Hello, world" # constant Constant = 'This is also constant' # constant my_variable = "Hello, venus" # not constatn Constant name start with capital letter. Everything that start with capital letter are considered as constant in Ruby. So class and module are al...

MY_CONSTANT = "Hello, world" MY_CONSTANT = "Hullo, world" The above code results in a warning, because you should be using variables if you want to change their values. However it is possible to change one letter at a time in a constant without a warning, like this: MY_CONST...

def say_hi MESSAGE = "Hello" puts MESSAGE end The above code results in an error: SyntaxError: (irb):2: dynamic constant assignment.

class Message DEFAULT_MESSAGE = "Hello, world" def speak(message = nil) if message puts message else puts DEFAULT_MESSAGE end end end The constant DEFAULT_MESSAGE can be changed with the following code: Message::DEFAULT_MESSAGE = "Hullo, wo...

Local variables (unlike the other variable classes) do not have any prefix local_variable = "local" p local_variable # => local Its scope is dependent on where it has been declared, it can not be used outside the "declaration containers" scope. For example, if a local va...

Class variables have a class wide scope, they can be declared anywhere in the class. A variable will be considered a class variable when prefixed with @@ class Dinosaur @@classification = "Like a Reptile, but like a bird" def self.classification @@classification ...

Global variables have a global scope and hence, can be used everywhere. Their scope is not dependent on where they are defined. A variable will be considered global, when prefixed with a $ sign. $i_am_global = "omg" class Dinosaur def instance_method p "global vars ca...

Instance variables have an object wide scope, they can be declared anywhere in the object, however an instance variable declared on class level, will only be visible in the class object. A variable will be considered an instance variable when prefixed with @. Instance variables are used to set and g...

def results = [] (1..4).each{ def what = (it%2) ? 'odd' : 'even' results << what } assert results == ['odd', 'even', 'odd', 'even'] Here, the if-condition (in (parentheses)) is slightly more complex than just testing for existence/Groovy-Truth.

A list of available IDEs to create classes, triggers, Visualforce/Lightning pages/components. Force.com IDE – plugin for Eclipse JedIDE – plugin for IntelliJ IDEA & standalone Force.com IDE MavensMate – plugin for Sublime Text and Atom and VS Code FuseIT SFDC Explorer - This is a standalon...

public void SaveNewEmployee(Employee newEmployee) { // best practice - wrap all database connections in a using block so they are always closed & disposed even in the event of an Exception // best practice - retrieve the connection string by name from the app.config or web.config (dep...

The easiest way to install and manage various versions of Ruby with rbenv is to use the ruby-build plugin. First clone the rbenv repository to your home directory: $ git clone https://github.com/rbenv/rbenv.git ~/.rbenv Then clone the ruby-build plugin: $ git clone https://github.com/rbenv/rub...

It is best to use latest SLIME from Emacs MELPA repository: the packages may be a bit unstable, but you get the latest features. Portale and multiplatform Emacs, Slime, Quicklisp, SBCL and Git You can download a portable and multiplatform version of Emacs25 already configured with Slime, SBCL, Qui...

In Emacs M-x slime will start slime with the default (first) Common Lisp implementation. If there are multiple implementations provided (via variable slime-lisp-implementations), other implementations can be accessed via M-- M-x slime, which will offer the choice of available implementations in mini...

CL-USER> (+ 2 3) 5 CL-USER> (sin 1.5) 0.997495 CL-USER> (mapcar (lambda (x) (+ x 2)) '(1 2 3)) (3 4 5) The result that is printed after evaluation is not only a string: there is full-on Lisp object behind it which can be inspected by right-clicking on it and choosing Inspect. Multi...

Examples ES6/ES2015 to ES5 (via Babel): This ES2015 syntax // ES2015 arrow function syntax [1,2,3].map(n => n + 1); is interpreted and translated to this ES5 syntax: // Conventional ES5 anonymous function syntax [1,2,3].map(function(n) { return n + 1; }); CoffeeScript to ...

// This iterates through a range between two DateTimes // with the given iterator (any of the Add methods) DateTime start = new DateTime(2016, 01, 01); DateTime until = new DateTime(2016, 02, 01); // NOTICE: As the add methods return a new DateTime you have // to overwrite dt in the itera...

C++17 namespace a { namespace b { template<class T> struct qualifies : std::false_type {}; } } namespace other { struct bob {}; } namespace a::b { template<> struct qualifies<::other::bob> : std::true_type {}; } You can enter both the a and b n...

Example: Invoke different constructors by passing relevant parameters import java.lang.reflect.*; class NewInstanceWithReflection{ public NewInstanceWithReflection(){ System.out.println("Default constructor"); } public NewInstanceWithReflection( String a){ ...