An Introduction to Object-Oriented Programming (DrupalCamp London 2015)
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The document provides an introduction to Object-Oriented Programming (OOP), explaining fundamental concepts such as classes, objects, methods, properties, and interfaces. It discusses various programming principles including inheritance, visibility, and traits, illustrating each with PHP code examples. The conclusion emphasizes that OOP enhances developer efficiency and reduces bugs.
![ABSTRACT CLASSES
Abstract classes provide partial implementations, but cannot be
instantiated.
<?php
abstract class AbstractFoo implements FooMultipleInterface {
public function doFoo($foo) {
return sprintf('Hello %s!', $foo);
}
}
class Foo extends AbstractFoo implements FooMultipleInterface {
public function doFooMultiple(array $foos) {
$greetings = [];
foreach ($foos as $foo) {
$greetings[] = sprintf('Hello %s!', $foo);
}
return implode(' ', $greetings);
}
}
$foo = new Foo();
$foo->doFooMultiple(['world', 'Drupal']);](https://image.slidesharecdn.com/anintroductiontoobject-orientedprogrammingdrupalcamplondon2015-150228113410-conversion-gate01/85/An-Introduction-to-Object-Oriented-Programming-DrupalCamp-London-2015-7-320.jpg)
![$THIS
$this points to the current object.
<?php
abstract class AbstractFoo implements FooMultipleInterface {
public function doFoo($foo) {
return sprintf('Hello %s!', $foo);
}
}
class Foo extends AbstractFoo implements FooMultipleInterface {
public function doFooMultiple(array $foos) {
$greetings = [];
foreach ($foos as $foo) {
$greetings[] = $this->doFoo($foo);
}
return implode(' ', $greetings);
}
}
$foo = new Foo();
$foo->doFooMultiple(['world', 'Drupal']);
// returns "Hello world!" and "Hello Drupal!"](https://image.slidesharecdn.com/anintroductiontoobject-orientedprogrammingdrupalcamplondon2015-150228113410-conversion-gate01/85/An-Introduction-to-Object-Oriented-Programming-DrupalCamp-London-2015-10-320.jpg)
An Introduction to Object-Oriented Programming (DrupalCamp London 2015)
- 1. AN INTRODUCTION TO OBJECT-ORIENTED PROGRAMMING (OOP) DrupalCamp London 2015
- 2. WHAT IS OBJECT-ORIENTED PROGRAMMING? The form of programming that uses instances (objects) of classes (predefined data types) to structure (group) information and functionality.
- 3. GLOSSARY Class A predefined type (blueprint) of complex data. Object An instance of a class; a single unit of complex data. Property A variable that belongs to a class or object. Method A function that belongs to a class or object.
- 4. STATE Objects have state (internal configuration) which can be changed. Most, if not all usages of static variables in Drupal 7 have been replaced with object properties in Drupal 8.
- 5. INTERFACES Interfaces define what objects must be able to do, but do not define how they must do these things. They are contracts that must be fulfilled. <?php interface FooInterface { public function doFoo($foo); } interface FooMultipleInterface extends FooInterface { public function doFooMultiple(array $foos); }
- 6. CLASSES Classes define what objects must do and how to do this. In good design, they implement interfaces. Classes can be instantiated into objects. <?php class Foo implements FooInterface { public function doFoo($foo) { return sprintf('Hello %s!', $foo); } } $foo = new Foo(); $foo->doFoo('world'); // returns "Hello world!"
- 7. ABSTRACT CLASSES Abstract classes provide partial implementations, but cannot be instantiated. <?php abstract class AbstractFoo implements FooMultipleInterface { public function doFoo($foo) { return sprintf('Hello %s!', $foo); } } class Foo extends AbstractFoo implements FooMultipleInterface { public function doFooMultiple(array $foos) { $greetings = []; foreach ($foos as $foo) { $greetings[] = sprintf('Hello %s!', $foo); } return implode(' ', $greetings); } } $foo = new Foo(); $foo->doFooMultiple(['world', 'Drupal']);
- 8. TRAITS Traits provide re-usable implementations that can reduce boilerplate code. Classes can use traits. <?php trait FooTrait { public function doFoo($foo) { return sprintf('Hello %s!', $foo); } } class Foo implements FooInterface { use FooTrait; } $foo = new Foo(); $foo->doFoo('world'); // returns "Hello world!"
- 9. INHERITANCE Interfaces, traits, and classes can be extended. Child classes can access methods from their parent classes. <?php class Foo implements FooInterface { public function doFoo($foo) { return sprintf('Hello %s!', $foo); } } class PoliteFoo extends Foo { public function doFoo($foo) { $message = parent::doFoo($foo); $message .= ' How are you?'; return $message; } } $foo = new Foo(); $foo->doFoo('world');
- 10. $THIS $this points to the current object. <?php abstract class AbstractFoo implements FooMultipleInterface { public function doFoo($foo) { return sprintf('Hello %s!', $foo); } } class Foo extends AbstractFoo implements FooMultipleInterface { public function doFooMultiple(array $foos) { $greetings = []; foreach ($foos as $foo) { $greetings[] = $this->doFoo($foo); } return implode(' ', $greetings); } } $foo = new Foo(); $foo->doFooMultiple(['world', 'Drupal']); // returns "Hello world!" and "Hello Drupal!"
- 11. VISIBILITY Developers control which methods can be called from outside the class. public Can be called from anywhere. protected Can be called only from within the class or any child class. private Can only be called from within the same class. <?php class Bar { protected function doBar() {} } $bar = new Bar(); $bar->doBar(); // $bar->doBar() causes an error, because we call a protected method from outside the class.
- 12. CHECKING AN OBJECT'S TYPE When accepted as a function parameter (type hinting). In a block of code (instanceof). <?php function foo(FooInterface $foo) { // Here we only know $foo implements FooInterface. if ($foo instanceof FooMultipleInterface) { // Now we know $foo implements FooMultipleInterface too. } }
- 13. AUTOLOADING USING PSR-4 Industry standard with several available autoloaders. Class names map to file names. Namespaces map to directory names. Much faster and less frustrating than the Drupal 7 registry. Example: DrupalpaymentEntityPaymentInterfacemaps to ./src/Entity/PaymentInterface.php.
- 14. BENEFITS Classes objects are faster than arrays ( ). Interfaces and classes are documentation. IDEs use interfaces and classes for code completion. Easier and faster coding. Lower chance of bugs. https://gist.github.com/nikic/5015323
- 15. CONCLUSION OOP MAKES YOU A BETTER DEVELOPER. Find this presentation at .https://github.com/bartfeenstra/presentation_intro_oop Find me at and .@BartFeenstra http://mynameisbart.com DO YOU HAVE ANY QUESTIONS?