Tutorial by Examples: class

Lets say we have a class as (defclass person () (name email age)) To obtain the names of the slots of the class we use the function class-slots. This can be found in the closer-mop package, provided by the closer-mop system. To load it the running lisp image we use (ql:quickload :closer-mop)....

In general, classes in Perl are just packages. They can contain data and methods, as usual packages. package Point; use strict; my $CANVAS_SIZE = [1000, 1000]; sub new { ... } sub polar_coordinates { ... } 1; It is important to note that the variables declared in a packa...

In Perl, the difference between class (static) and object (instance) methods is not so strong as in some other languages, but it still exists. The left operand of the arrow operator -> becomes the first argument of the method to be called. It may be either a string: # the first argument of new ...

The dir() function can be used to get a list of the members of a class: dir(Class) For example: >>> dir(list) ['__add__', '__class__', '__contains__', '__delattr__', '__delitem__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__gt__', '__...

Strategy: Strategy is a behavioural pattern, which allows to change the algorithm dynamically from a family of related algorithms. UML of Strategy pattern from Wikipedia : import java.util.*; /* Interface for Strategy */ interface OfferStrategy { public String getName(); public dou...

1. Character Class Character class is denoted by []. Content inside a character class is treated as single character separately. e.g. suppose we use [12345] In the example above, it means match 1 or 2 or 3 or 4 or 5 . In simple words, it can be understood as or condition for single characters (...

<!-- <moduleDir>/etc/<area>/di.xml --> <config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd"> <!-- ... --> <preference for="Vendor\Name...

// class declaration with a list of parameters for a primary constructor type Car (model: string, plates: string, miles: int) = // secondary constructor (it must call primary constructor) new (model, plates) = let miles = 0 new Car(model, plates, miles) ...

You can subclass SKSpriteNode and define your own type of sprite. class Hero: SKSpriteNode { //Use a convenience init when you want to hard code values convenience init() { let texture = SKTexture(imageNamed: "Hero") self.init(texture: texture, color: .clearCol...

You will often need to access instances of classes from the framework itself (like the WSClient, or the Configuration). You can inject them in your own classes : class ComplexService @Inject()( configuration: Configuration, wsClient: WSClient, applicationLifecycle: ApplicationLifecycle, ...

Mongoid allows the classic ActiveRecord associations: One-to-one: has_one / belongs_to One-to-many: has_many / belongs_to Many-to-many: has_and_belongs_to_many To add an association (lets say the User has_many posts), you can add this to your User model file: has_many :posts and this to ...

The first thing you need to know when structuring your apps is that the Meteor tool has some directories that are hard-coded with specific logic. At a very basic level, the following directories are "baked in" the Meteor bundler. client/ # client applicati...

1) Create a Contract Class A contract class defines constants that help applications work with the content URIs, column names, intent actions, and other features of a content provider. Contract classes are not included automatically with a provider; the provider's developer has to define them and t...

A class, functions as a template that defines the basic characteristics of a particular object. Here's an example: class Person(object): """A simple class.""" # docstring species = "Homo Sapiens" ...

Modern browsers provide a classList object to ease manipulation of the element's class attribute. Older browsers require direct manipulation of the element's className property. W3C DOM4 A simple method to add a class to an element is to append it to the end of the className property. This will no...

class A: x = None # type: float def __init__(self, x: float) -> None: """ self should not be annotated init should be annotated to return None """ self.x = x @classmethod def from_int(cls, x: int...

A singleton is a pattern that restricts the instantiation of a class to one instance/object. Using a decorator, we can define a class as a singleton by forcing the class to either return an existing instance of the class or create a new instance (if it doesn't exist). def singleton(cls): i...

Disclaimer: the examples presented here are only for the purpose of showing the use of abstract classes and inheritance and may not necessarily be of a practical use. Also, there is no sich thing as polymorphic in MATLAB and therefore the use of abstract classes is limited. This example is to show w...

A whole class may be declared as friend. Friend class declaration means that any member of the friend may access private and protected members of the declaring class: class Accesser { public: void private_accesser1(); void private_accesser2(); }; class PrivateHolder { public: P...

Over time, our classes may implement more and more interfaces. When these interfaces have many methods, the total number of methods in our class will become very large. For example, let's suppose that we have two interfaces and a class implementing them: interface Printable { public functio...