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DemystifyingObject-Oriented Programming
Download Files:https://github.com/sketchings/oop-basics
https://joind.in/talk/153b4
Presented by: Alena Holligan• Wife and Mother of 3 young children
• PHP Teacher at Treehouse
• Group Leader (PHPDX, Women Who Code Portland)
www.sketchings.com@[email protected]
Terminologythe single most important part
PART 1: TermsClass (properties, methods)
Object
Instance
Abstraction
Encapsulation
PART 2: PolymorphismInheritance
Interface
Abstract Class
Traits
Part 3: ADDED FEATURESNamespaces
Type Declarations
Static Methods
Magic Methods
Magic Constants
Class
A template/blueprint that facilitates creation of objects. A set of program statements to do a certain task. Usually represents a noun, such as a person, place or thing.
Includes properties and methods — which are class functions
Object
Instance of a class.
In the real world object is a material thing that can be seen and touched.
In OOP, object is a self-contained entity that consists of both data and procedures.
Instance
Single occurrence/copy of an object
There might be one or several objects, but an instance is a specific copy, to which you can have a reference
class User { //class private $name; //property public function getName() { //method echo $this->name; //current object property }}
$user1 = new User(); //first instance of object
$user2 = new User(); //second instance of object
Abstraction
Managing the complexity of the system
Dealing with ideas rather than events
This is the class architecture itself.
Use something without knowing inner workings
Encapsulation
Binds together the data and functions that manipulate the data, and keeps both safe from outside interference and misuse.
Properties
Methods
ScopeControls who can access what. Restricting access to some of the object’s components (properties and methods), preventing unauthorized access.
Public - everyone
Protected - inherited classes
Private - class itself, not children
class User { protected $name; protected $title; public function getFormattedSalutation() { return $this->getSalutation(); } protected function getSalutation() { return $this->title . " " . $this->name; } public function getName() { return $this->name; } public function setName($name) { $this->name = $name; } public function getTitle() { return $this->title; } public function setTitle($title) { $this->title = $title; } }
Creating / Using the object Instance$user = new User(); $user->setName("Jane Smith"); $user->setTitle("Ms"); echo $user->getFormattedSalutation();
When the script is run, it will return:
Ms Jane Smith
Team-upoop is great for working in groups
Challenges
1. Create a new class with properties and methods
2. Instantiate a new user with a different name and title
3. Throw an error because your access is too restricted.
https://github.com/sketchings/oop-basics
PART 2: PolymorphismD-R-YSharing Code
pol·y·mor·phism /ˌpälēˈmôrfizəm/The condition of occurring in several different forms
BIOLOGY
GENETICS
BIOCHEMISTRY
COMPUTING
TermsPolymorphism
Inheritance
Interface
Abstract Class
Traits
Inheritance: passes knowledge down
Subclass, parent and a child relationship, allows for reusability, extensibility.
Additional code to an existing class without modifying it. Uses keyword “extends”
NUTSHELL: create a new class based on an existing class with more data, create new objects based on this class
Creating a child class
class Developer extends User { public $skills = array(); //additional property
public function getSalutation() {//override method return $this->title . " " . $this->name. ", Developer"; } public function getSkillsString(){ //additional method return implode(", ",$this->skills); } }
Using a child class
$developer = new Developer(); $developer->setName(”Jane Smith”); $developer->setTitle(“Ms”);
echo $developer->getFormatedSalutation();echo "<br />”;
$developer->skills = array("JavasScript", "HTML", "CSS");$developer->skills[] = “PHP";
echo $developer->getSkillsString();
When run, the script returns:
Ms Jane Smith, Developer
JavasScript, HTML, CSS, PHP
Interface
Interface, specifies which methods a class must implement.
All methods in interface must be public.
Multiple interfaces can be implemented by using comma separation
Interface may contain a CONSTANT, but may not be overridden by implementing class
interface UserInterface {
public function getFormattedSalutation();
public function getName();
public function setName($name);
public function getTitle();
public function setTitle($title);
}
class User implements UserInterface { … }
Abstract Class
An abstract class is a mix between an interface and a class. It can define functionality as well as interface.
Classes extending an abstract class must implement all of the abstract methods defined in the abstract class.
abstract class User { //class
public $name; //property
public getName() { //method echo $this->name; }
abstract public function setName($name); //abstract method}
class Developer extends User { public setName($name) { //implementing the method …
Traits
Composition
Horizontal Code Reuse
Multiple traits can be implemented
Creating Traitstrait Toolkit { public $tools = array(); public function setTools($task) { switch ($task) { case “eat": $this->tools[] = array("Spoon", "Fork", "Knife"); exit; ... } } public function showTools() { return implode(", ",$this->skills); } }
Using Traitsclass Developer extends User { use Toolkit; ... }
$developer = new Developer(); $developer->setName(”Jane Smith”); $developer->setTitle(”Ms”); echo $developer; echo "<br />"; $developer->setTools("Eat"); echo $developer->showTools();
When run, the script returns:
Ms Jane Smith
Spoon, Fork, Knife
Challenges1. Change to User class to an abstract class.
2. Extend the User class for another type of user, such as our Developer example
3. Add an Interface for the Developer Class (or your own class)
4. Add a trait to the User
https://github.com/sketchings/oop-basics
Part 3: Added FeaturesNamespaces
Type Declarations
Magic Methods
Magic Constants
Static Methods
NamespacesPrevent Code Collision
Help create a new layer of code encapsulation
Keep properties from colliding between areas of your code
Only classes, interfaces, functions and constants are affected
Anything that does not have a namespace is considered in the Global namespace (namespace = "")
NamespacesMust be declared first (except 'declare)
Can define multiple in the same file
You can define that something be used in the "Global" namespace by enclosing a non-labeled namespace in {} brackets.
Use namespaces from within other namespaces, along with aliasing
namespace myUser;
class User { //class
public $name; //property
public getName() { //method
echo $this->name;
}
public function setName($name);
}
class Developer extends \myUser\User { … }
Available Type DeclarationsPHP 5.4
Class/Interface,
self, array,
callable
PHP 7
bool
float
int
string
Type Declarationsclass Conference { public $title; private $attendees = array(); public function addAttendee(User $person) { $this->attendees[] = $person; } public function getAttendees(): array { foreach($this->attendees as $person) { $attendee_list[] = $person; } return $attendee_list; } }
Using Type Declarations
$zendcon = new Conference(); $zendcon->title = ”ZendCon 2016”; $zendcon->addAttendee($user); echo implode(", “, $zendcon->getAttendees());
When the script is run, it will return the same result as before:
Ms Jane Smith
Magic Methods
Setup just like any other method
The Magic comes from the fact that they are triggered and not called
For more see http://php.net/manual/en/language.oop5.magic.php
Magic Constants
Predefined functions in PHP
For more see http://php.net/manual/en/language.constants.predefined.php
Magic Methods and Constantsclass User { protected $name; protected $title; public function __construct($name, $title) { $this->name = $name; $this->title = $title; } public function __toString() { return __CLASS__. “: “ . $this->getFormattedSalutation(); } ... }
Creating / Using the Magic Method$user = new User("Jane Smith","Ms"); echo $user;
When the script is run, it will return the same result as before:
User: Ms Jane Smith
Adding a Static Methodsclass User { public $encouragements = array( “You are beautiful!”, “You have this!”, public static function encourage() { $int = rand(count($this->encouragements)); return $this->encouragements[$int]; } ... }
Using the Static Methodecho User::encourage();
When the script is run, it will return the same result as before:
You have this!
Challenges1. Define 2 “User” classes. Use both classes in one file using
namespacing
2. Try defining types AND try accepting/returning the wrong types
3. Try another Magic Method http://php.net/manual/en/language.oop5.magic.php
4. Add Magic Constants http://php.net/manual/en/language.constants.predefined.php
5. Add and use a Static Method
https://github.com/sketchings/oop-basics
Resources
LeanPub: The Essentials of Object Oriented PHP
Head First Object-Oriented Analysis and Design
Presented by: Alena Holligan• Wife and Mother of 3 young children
• PHP Teacher at Treehouse
• Group Leader (PHPDX, Women Who Code Portland)
www.sketchings.com @[email protected]
Download Files: https://github.com/sketchings/oop-basics
https://joind.in/talk/153b4