Unlike inheritance; if a trait has static properties, each class using that trait has independent instances of those properties.
Example using parent class:
<?php
class TestClass {
public static $_bar;
}
class Foo1 extends TestClass { }
class Foo2 extends TestClass { }
Foo1::$_bar = 'Hello';
Foo2::$_bar = 'World';
echo Foo1::$_bar . ' ' . Foo2::$_bar; // Prints: World World
?>
Example using trait:
<?php
trait TestTrait {
public static $_bar;
}
class Foo1 {
use TestTrait;
}
class Foo2 {
use TestTrait;
}
Foo1::$_bar = 'Hello';
Foo2::$_bar = 'World';
echo Foo1::$_bar . ' ' . Foo2::$_bar; // Prints: Hello World
?>
트레이트
PHP 5.4.0 부터, 트레이트 라는 코드 재사용 방법을 구현했습니다.
트레이트는 PHP와 같은 단일상속 언어를 위한 코드 재사용 기법입니다. 트레이트는 단일상속의 몇가지 한계를 줄이기 위해 고안되었습니다. 개발자들은 서로 다른 클래스 계층구조를 가지는 독립 클래스들에서 자유롭게 메서드셋을 재사용할수 있습니다. 트레이트와 클래스의 조합에 대한 의의는 복잡성을 줄이고, 다중상속과 믹스인(Mixin)과 연관된 통상적인 문제를 줄이는데 있습니다.
트레이트는 클래스와 비슷하지만, 매끄럽고 일관된 방법으로 기능을 그룹화하기 위해 고안되었습니다. 트레이트는 자신을 인스턴스화할 수 없습니다. 트레이트는 기존의 상속을 확장하고, 수평적으로 동작을 내재화 할수 있도록 합니다. 이말은, 상속없이 클래스 멤버에 추가할수 있음을 의미합니다.
Example #1 트레이트 예제
<?php
trait ezcReflectionReturnInfo {
function getReturnType() { /*1*/ }
function getReturnDescription() { /*2*/ }
}
class ezcReflectionMethod extends ReflectionMethod {
use ezcReflectionReturnInfo;
/* ... */
}
class ezcReflectionFunction extends ReflectionFunction {
use ezcReflectionReturnInfo;
/* ... */
}
?>
우선순위
기본 클래스로부터 상속된 멤버는 트레이트의 의해 추가된 멤버에 의한 방법이 우선 됩니다. 우선순위는 현재 클래스의 멤버를 트레이트의 메서드로 재정의하고, 그 다음이 상속된 메서드를 재정의하는 순서입니다.
Example #2 우선순위 예제
기본 클래스로부터 상속된 메서드는 MyHelloWorld 에 추가된 SayWorld 트레이트의 메서드의해 재정의됩니다. MyHelloWord 클래스에 메서드가 정의된것과 같이 동작합니다. 우선순위는 현재클래스의 메서드를 트레이트 메서드로 재정의하고, 그 다음으로 기본 클래스의 메서드를 재정의하는 순서입니다.
<?php
class Base {
public function sayHello() {
echo 'Hello ';
}
}
trait SayWorld {
public function sayHello() {
parent::sayHello();
echo 'World!';
}
}
class MyHelloWorld extends Base {
use SayWorld;
}
$o = new MyHelloWorld();
$o->sayHello();
?>
위 예제의 출력:
Hello World!
Example #3 다른 우선순위 예제
<?php
trait HelloWorld {
public function sayHello() {
echo 'Hello World!';
}
}
class TheWorldIsNotEnough {
use HelloWorld;
public function sayHello() {
echo 'Hello Universe!';
}
}
$o = new TheWorldIsNotEnough();
$o->sayHello();
?>
위 예제의 출력:
Hello Universe!
다중 트레이트
다중 트레이트는 콤마로 구분하여 클래스에 삽입될수 있습니다.
Example #4 다중 트레이트 사용법
<?php
trait Hello {
public function sayHello() {
echo 'Hello ';
}
}
trait World {
public function sayWorld() {
echo 'World';
}
}
class MyHelloWorld {
use Hello, World;
public function sayExclamationMark() {
echo '!';
}
}
$o = new MyHelloWorld();
$o->sayHello();
$o->sayWorld();
$o->sayExclamationMark();
?>
위 예제의 출력:
Hello World!
충돌 해결
같은 메서드 이름을 가진 트레이트가 삽입된다면, 충돌이 명시적으로 해결되지 않는한 치명적인(fatal) 에러가 날것입니다.
동일 클래스내에서 트레이트들간의 이름 충돌을 해결하기 위해서는, insteadof 연산자로 확실하게 사용할 메서드를 골라줄 필요가 있습니다.
이 방법은 다른 메서드들을 배제하고 하나의 메서드만 허용합니다. as 연산자를 사용하면 충돌되는 메서드를 다른 이름을 사용하여 포함할수 있습니다.
Example #5 충돌 해결 예제
이 예제에서, Talker는 트레이트 A와 B를 사용합니다. A와 B의 메서드가 충돌하지만, 트레이트 B의 smallTalk와 트레이트 A의 bigTalk의 사용하도록 정의 합니다.
Aliased_Talker는 as 연산자를 사용하여 B의 bigTalk 구현을 talk 로 별칭을 사용하도록 만듭니다.
<?php
trait A {
public function smallTalk() {
echo 'a';
}
public function bigTalk() {
echo 'A';
}
}
trait B {
public function smallTalk() {
echo 'b';
}
public function bigTalk() {
echo 'B';
}
}
class Talker {
use A, B {
B::smallTalk insteadof A;
A::bigTalk insteadof B;
}
}
class Aliased_Talker {
use A, B {
B::smallTalk insteadof A;
A::bigTalk insteadof B;
B::bigTalk as talk;
}
}
?>
메서드 가시성 변경
as 구문을 사용하여, 가시성 또한 조정할 수 있습니다.
Example #6 메서드 가시성 변경 예제
<?php
trait HelloWorld {
public function sayHello() {
echo 'Hello World!';
}
}
// sayHello 가시성 변경
class MyClass1 {
use HelloWorld { sayHello as protected; }
}
// 메서드를 별칭을 지정하여 가시성을 변경하면
// sayHello 의 가시성은 변경되지 않습니다.
class MyClass2 {
use HelloWorld { sayHello as private myPrivateHello; }
}
?>
트레이트로 조합된 트레이트
클래스들이 트레이트를 사용할수 있는것처럼 트레이트도 트레이트를 사용할 수 있습니다. 하나 또는 여러 트레이트를 하나의 트레이트로 정의하기 위해서, 부분적 혹은 전체적으로 조합할 수 있습니다.
Example #7 Traits Composed from Traits
<?php
trait Hello {
public function sayHello() {
echo 'Hello ';
}
}
trait World {
public function sayWorld() {
echo 'World!';
}
}
trait HelloWorld {
use Hello, World;
}
class MyHelloWorld {
use HelloWorld;
}
$o = new MyHelloWorld();
$o->sayHello();
$o->sayWorld();
?>
위 예제의 출력:
Hello World!
추상 트레이트 멤버
트레이트는 클래스의 요구사항을 강요하기위해 추상 메서드의 사용을 지원합니다.
Example #8 추상 메서드에 의한 요구사항 표현
<?php
trait Hello {
public function sayHelloWorld() {
echo 'Hello'.$this->getWorld();
}
abstract public function getWorld();
}
class MyHelloWorld {
private $world;
use Hello;
public function getWorld() {
return $this->world;
}
public function setWorld($val) {
$this->world = $val;
}
}
?>
정적 트레이트 멤버
트레이트는 정적 멤버와 정적 메서드로 정의 가능합니다.
Example #9 정적 변수
<?php
trait Counter {
public function inc() {
static $c = 0;
$c = $c + 1;
echo "$c\n";
}
}
class C1 {
use Counter;
}
class C2 {
use Counter;
}
$o = new C1(); $o->inc(); // echo 1
$p = new C2(); $p->inc(); // echo 1
?>
Example #10 정적 메서드
<?php
trait StaticExample {
public static function doSomething() {
return 'Doing something';
}
}
class Example {
use StaticExample;
}
Example::doSomething();
?>
프로퍼티
트레이트는 프로퍼티를 정의할 수 있습니다.
Example #11 프로퍼티 정의
<?php
trait PropertiesTrait {
public $x = 1;
}
class PropertiesExample {
use PropertiesTrait;
}
$example = new PropertiesExample;
$example->x;
?>
트레이트가 프로퍼티를 정의하면 클래스는 같은 이름으로 프로퍼티를 정의할수 없습니다. 그렇지 않을 경우 에러가 발생합니다.
E_STRICT 는 클래스 정의가 동일할때(같은 가시성과 초기값을 가진경우) 발생하며, 그렇지 않을경우에는 치명적인 에러가 발생합니다.
Example #12 충돌 해결
<?php
trait PropertiesTrait {
public $same = true;
public $different = false;
}
class PropertiesExample {
use PropertiesTrait;
public $same = true; // Strict Standards
public $different = true; // Fatal error
}
?>
add a note
User Contributed Notes 25 notes
Safak Ozpinar / safakozpinar at gmail ¶
12 years ago
greywire at gmail dot com ¶
12 years ago
The best way to understand what traits are and how to use them is to look at them for what they essentially are: language assisted copy and paste.
If you can copy and paste the code from one class to another (and we've all done this, even though we try not to because its code duplication) then you have a candidate for a trait.
Stefan W ¶
11 years ago
Note that the "use" operator for traits (inside a class) and the "use" operator for namespaces (outside the class) resolve names differently. "use" for namespaces always sees its arguments as absolute (starting at the global namespace):
<?php
namespace Foo\Bar;
use Foo\Test; // means \Foo\Test - the initial \ is optional
?>
On the other hand, "use" for traits respects the current namespace:
<?php
namespace Foo\Bar;
class SomeClass {
use Foo\Test; // means \Foo\Bar\Foo\Test
}
?>
Together with "use" for closures, there are now three different "use" operators. They all mean different things and behave differently.
JustAddingSomeAdditionalUseCase ¶
1 year ago
I have not seen this specific use case:
"Wanting to preserve action of parent class method, the trait one calling ::parent & also the child class mehod action".
// Child class.
use SuperTrait {
initialize as initializeOr;
}
public function initialize(array &$element) {
...
$this->initializeOr($element);
}
// Trait.
public function initialize(array &$element) {
...
parent::initialize($element);
}
// Parent class.
public function initialize(array &$element) {
...
}
t8 at AT pobox dot com ¶
12 years ago
Another difference with traits vs inheritance is that methods defined in traits can access methods and properties of the class they're used in, including private ones.
For example:
<?php
trait MyTrait
{
protected function accessVar()
{
return $this->var;
}
}
class TraitUser
{
use MyTrait;
private $var = 'var';
public function getVar()
{
return $this->accessVar();
}
}
$t = new TraitUser();
echo $t->getVar(); // -> 'var'
?>
chris dot rutledge at gmail dot com ¶
12 years ago
It may be worth noting here that the magic constant __CLASS__ becomes even more magical - __CLASS__ will return the name of the class in which the trait is being used.
for example
<?php
trait sayWhere {
public function whereAmI() {
echo __CLASS__;
}
}
class Hello {
use sayWHere;
}
class World {
use sayWHere;
}
$a = new Hello;
$a->whereAmI(); //Hello
$b = new World;
$b->whereAmI(); //World
?>
The magic constant __TRAIT__ will giev you the name of the trait
qeremy (!) gmail ¶
9 years ago
Keep in mind; "final" keyword is useless in traits when directly using them, unlike extending classes / abstract classes.
<?php
trait Foo {
final public function hello($s) { print "$s, hello!"; }
}
class Bar {
use Foo;
// Overwrite, no error
final public function hello($s) { print "hello, $s!"; }
}
abstract class Foo {
final public function hello($s) { print "$s, hello!"; }
}
class Bar extends Foo {
// Fatal error: Cannot override final method Foo::hello() in ..
final public function hello($s) { print "hello, $s!"; }
}
?>
But this way will finalize trait methods as expected;
<?php
trait FooTrait {
final public function hello($s) { print "$s, hello!"; }
}
abstract class Foo {
use FooTrait;
}
class Bar extends Foo {
// Fatal error: Cannot override final method Foo::hello() in ..
final public function hello($s) { print "hello, $s!"; }
}
?>
rawsrc ¶
6 years ago
About the (Safak Ozpinar / safakozpinar at gmail)'s great note, you can still have the same behavior than inheritance using trait with this approach :
<?php
trait TestTrait {
public static $_bar;
}
class FooBar {
use TestTrait;
}
class Foo1 extends FooBar {
}
class Foo2 extends FooBar {
}
Foo1::$_bar = 'Hello';
Foo2::$_bar = 'World';
echo Foo1::$_bar . ' ' . Foo2::$_bar; // Prints: World World
canufrank ¶
8 years ago
A number of the notes make incorrect assertions about trait behaviour because they do not extend the class.
So, while "Unlike inheritance; if a trait has static properties, each class using that trait has independent instances of those properties.
Example using parent class:
<?php
class TestClass {
public static $_bar;
}
class Foo1 extends TestClass { }
class Foo2 extends TestClass { }
Foo1::$_bar = 'Hello';
Foo2::$_bar = 'World';
echo Foo1::$_bar . ' ' . Foo2::$_bar; // Prints: World World
?>
Example using trait:
<?php
trait TestTrait {
public static $_bar;
}
class Foo1 {
use TestTrait;
}
class Foo2 {
use TestTrait;
}
Foo1::$_bar = 'Hello';
Foo2::$_bar = 'World';
echo Foo1::$_bar . ' ' . Foo2::$_bar; // Prints: Hello World
?>"
shows a correct example, simply adding
<?php
require_once('above');
class Foo3 extends Foo2 {
}
Foo3::$_bar = 'news';
echo Foo1::$_bar . ' ' . Foo2::$_bar . ' ' . Foo3::$_bar;
// Prints: Hello news news
I think the best conceptual model of an incorporated trait is an advanced insertion of text, or as someone put it "language assisted copy and paste." If Foo1 and Foo2 were defined with $_bar, you would not expect them to share the instance. Similarly, you would expect Foo3 to share with Foo2, and it does.
Viewing this way explains away a lot of the 'quirks' that are observed above with final, or subsequently declared private vars,
yeu_ym at yahoo dot com ¶
5 years ago
Here is an example how to work with visiblity and conflicts.
<?php
trait A
{
private function smallTalk()
{
echo 'a';
}
private function bigTalk()
{
echo 'A';
}
}
trait B
{
private function smallTalk()
{
echo 'b';
}
private function bigTalk()
{
echo 'B';
}
}
trait C
{
public function smallTalk()
{
echo 'c';
}
public function bigTalk()
{
echo 'C';
}
}
class Talker
{
use A, B, C {
//visibility for methods that will be involved in conflict resolution
B::smallTalk as public;
A::bigTalk as public;
//conflict resolution
B::smallTalk insteadof A, C;
A::bigTalk insteadof B, C;
//aliases with visibility change
B::bigTalk as public Btalk;
A::smallTalk as public asmalltalk;
//aliases only, methods already defined as public
C::bigTalk as Ctalk;
C::smallTalk as cmallstalk;
}
}
(new Talker)->bigTalk();//A
(new Talker)->Btalk();//B
(new Talker)->Ctalk();//C
(new Talker)->asmalltalk();//a
(new Talker)->smallTalk();//b
(new Talker)->cmallstalk();//c
qschuler at neosyne dot com ¶
10 years ago
Note that you can omit a method's inclusion by excluding it from one trait in favor of the other and doing the exact same thing in the reverse way.
<?php
trait A {
public function sayHello()
{
echo 'Hello from A';
}
public function sayWorld()
{
echo 'World from A';
}
}
trait B {
public function sayHello()
{
echo 'Hello from B';
}
public function sayWorld()
{
echo 'World from B';
}
}
class Talker {
use A, B {
A::sayHello insteadof B;
A::sayWorld insteadof B;
B::sayWorld insteadof A;
}
}
$talker = new Talker();
$talker->sayHello();
$talker->sayWorld();
?>
The method sayHello is imported, but the method sayWorld is simply excluded.
ryan at derokorian dot com ¶
12 years ago
Simple singleton trait.
<?php
trait singleton {
/**
* private construct, generally defined by using class
*/
//private function __construct() {}
public static function getInstance() {
static $_instance = NULL;
$class = __CLASS__;
return $_instance ?: $_instance = new $class;
}
public function __clone() {
trigger_error('Cloning '.__CLASS__.' is not allowed.',E_USER_ERROR);
}
public function __wakeup() {
trigger_error('Unserializing '.__CLASS__.' is not allowed.',E_USER_ERROR);
}
}
/**
* Example Usage
*/
class foo {
use singleton;
private function __construct() {
$this->name = 'foo';
}
}
class bar {
use singleton;
private function __construct() {
$this->name = 'bar';
}
}
$foo = foo::getInstance();
echo $foo->name;
$bar = bar::getInstance();
echo $bar->name;
marko at newvibrations dot net ¶
8 years ago
As already noted, static properties and methods in trait could be accessed directly using trait. Since trait is language assisted c/p, you should be aware that static property from trait will be initialized to the value trait property had in the time of class declaration.
Example:
<?php
trait Beer {
protected static $type = 'Light';
public static function printed(){
echo static::$type.PHP_EOL;
}
public static function setType($type){
static::$type = $type;
}
}
class Ale {
use Beer;
}
Beer::setType("Dark");
class Lager {
use Beer;
}
Beer::setType("Amber");
header("Content-type: text/plain");
Beer::printed(); // Prints: Amber
Ale::printed(); // Prints: Light
Lager::printed(); // Prints: Dark
?>
Edward ¶
12 years ago
The difference between Traits and multiple inheritance is in the inheritance part. A trait is not inherited from, but rather included or mixed-in, thus becoming part of "this class". Traits also provide a more controlled means of resolving conflicts that inevitably arise when using multiple inheritance in the few languages that support them (C++). Most modern languages are going the approach of a "traits" or "mixin" style system as opposed to multiple-inheritance, largely due to the ability to control ambiguities if a method is declared in multiple "mixed-in" classes.
Also, one can not "inherit" static member functions in multiple-inheritance.
balbuf ¶
8 years ago
(It's already been said, but for the sake of searching on the word "relative"...)
The "use" keyword to import a trait into a class will resolve relative to the current namespace and therefore should include a leading slash to represent a full path, whereas "use" at the namespace level is always absolute.
guidobelluomo at gmail dot com ¶
4 years ago
If you override a method which was defined by a trait, calling the parent method will also call the trait's override. Therefore if you need to derive from a class which has a trait, you can extend the class without losing the trait's functionality:
<?php
trait ExampleTrait
{
public function output()
{
parent::output();
echo "bar<br>";
}
}
class Foo
{
public function output()
{
echo "foo<br>";
}
}
class FooBar extends Foo
{
use ExampleTrait;
}
class FooBarBaz extends FooBar
{
use ExampleTrait;
public function output()
{
parent::output();
echo "baz";
}
}
(new FooBarBaz())->output();
?>
Output:
foo
bar
baz
Kristof ¶
10 years ago
don't forget you can create complex (embedded) traits as well
<?php
trait Name {
// ...
}
trait Address {
// ...
}
trait Telephone {
// ...
}
trait Contact {
use Name, Address, Telephone;
}
class Customer {
use Contact;
}
class Invoce {
use Contact;
}
?>
D. Marti ¶
12 years ago
Traits are useful for strategies, when you want the same data to be handled (filtered, sorted, etc) differently.
For example, you have a list of products that you want to filter out based on some criteria (brands, specs, whatever), or sorted by different means (price, label, whatever). You can create a sorting trait that contains different functions for different sorting types (numeric, string, date, etc). You can then use this trait not only in your product class (as given in the example), but also in other classes that need similar strategies (to apply a numeric sort to some data, etc).
<?php
trait SortStrategy {
private $sort_field = null;
private function string_asc($item1, $item2) {
return strnatcmp($item1[$this->sort_field], $item2[$this->sort_field]);
}
private function string_desc($item1, $item2) {
return strnatcmp($item2[$this->sort_field], $item1[$this->sort_field]);
}
private function num_asc($item1, $item2) {
if ($item1[$this->sort_field] == $item2[$this->sort_field]) return 0;
return ($item1[$this->sort_field] < $item2[$this->sort_field] ? -1 : 1 );
}
private function num_desc($item1, $item2) {
if ($item1[$this->sort_field] == $item2[$this->sort_field]) return 0;
return ($item1[$this->sort_field] > $item2[$this->sort_field] ? -1 : 1 );
}
private function date_asc($item1, $item2) {
$date1 = intval(str_replace('-', '', $item1[$this->sort_field]));
$date2 = intval(str_replace('-', '', $item2[$this->sort_field]));
if ($date1 == $date2) return 0;
return ($date1 < $date2 ? -1 : 1 );
}
private function date_desc($item1, $item2) {
$date1 = intval(str_replace('-', '', $item1[$this->sort_field]));
$date2 = intval(str_replace('-', '', $item2[$this->sort_field]));
if ($date1 == $date2) return 0;
return ($date1 > $date2 ? -1 : 1 );
}
}
class Product {
public $data = array();
use SortStrategy;
public function get() {
// do something to get the data, for this ex. I just included an array
$this->data = array(
101222 => array('label' => 'Awesome product', 'price' => 10.50, 'date_added' => '2012-02-01'),
101232 => array('label' => 'Not so awesome product', 'price' => 5.20, 'date_added' => '2012-03-20'),
101241 => array('label' => 'Pretty neat product', 'price' => 9.65, 'date_added' => '2012-04-15'),
101256 => array('label' => 'Freakishly cool product', 'price' => 12.55, 'date_added' => '2012-01-11'),
101219 => array('label' => 'Meh product', 'price' => 3.69, 'date_added' => '2012-06-11'),
);
}
public function sort_by($by = 'price', $type = 'asc') {
if (!preg_match('/^(asc|desc)$/', $type)) $type = 'asc';
switch ($by) {
case 'name':
$this->sort_field = 'label';
uasort($this->data, array('Product', 'string_'.$type));
break;
case 'date':
$this->sort_field = 'date_added';
uasort($this->data, array('Product', 'date_'.$type));
break;
default:
$this->sort_field = 'price';
uasort($this->data, array('Product', 'num_'.$type));
}
}
}
$product = new Product();
$product->get();
$product->sort_by('name');
echo '<pre>'.print_r($product->data, true).'</pre>';
?>
bscheshirwork at gmail dot com ¶
7 years ago
https://3v4l.org/mFuQE
1. no deprecate if same-class-named method get from trait
2. replace same-named method ba to aa in C
trait ATrait {
public function a(){
return 'Aa';
}
}
trait BTrait {
public function a(){
return 'Ba';
}
}
class C {
use ATrait{
a as aa;
}
use BTrait{
a as ba;
}
public function a() {
return static::aa() . static::ba();
}
}
$o = new C;
echo $o->a(), "\n";
class D {
use ATrait{
ATrait::a as aa;
}
use BTrait{
BTrait::a as ba;
}
public function a() {
return static::aa() . static::ba();
}
}
$o = new D;
echo $o->a(), "\n";
class E {
use ATrait{
ATrait::a as aa;
ATrait::a insteadof BTrait;
}
use BTrait{
BTrait::a as ba;
}
public function e() {
return static::aa() . static::ba();
}
}
$o = new E;
echo $o->e(), "\n";
class F {
use ATrait{
a as aa;
}
use BTrait{
a as ba;
}
public function f() {
return static::aa() . static::ba();
}
}
$o = new F;
echo $o->f(), "\n";
AaAa
AaBa
Deprecated: Methods with the same name as their class will not be constructors in a future version of PHP; E has a deprecated constructor in /in/mFuQE on line 48
AaBa
Fatal error: Trait method a has not been applied, because there are collisions with other trait methods on F in /in/mFuQE on line 65
cody at codysnider dot com ¶
7 years ago
/*
DocBlocks pertaining to the class or trait will NOT be carried over when applying the trait.
Results trying a couple variations on classes with and without DocBlocks that use a trait with a DocBlock
*/
<?php
/**
* @Entity
*/
trait Foo
{
protected $foo;
}
/**
* @HasLifecycleCallbacks
*/
class Bar
{
use \Foo;
protected $bar;
}
class MoreBar
{
use \Foo;
protected $moreBar;
}
$w = new \ReflectionClass('\Bar');
echo $w->getName() . ":\r\n";
echo $w->getDocComment() . "\r\n\r\n";
$x = new \ReflectionClass('\MoreBar');
echo $x->getName() . ":\r\n";
echo $x->getDocComment() . "\r\n\r\n";
$barObj = new \Bar();
$y = new \ReflectionClass($barObj);
echo $y->getName() . ":\r\n";
echo $y->getDocComment() . "\r\n\r\n";
foreach($y->getTraits() as $traitObj) {
echo $y->getName() . " ";
echo $traitObj->getName() . ":\r\n";
echo $traitObj->getDocComment() . "\r\n";
}
$moreBarObj = new \MoreBar();
$z = new \ReflectionClass($moreBarObj);
echo $z->getName() . " ";
echo $z->getDocComment() . "\r\n\r\n";
foreach($z->getTraits() as $traitObj) {
echo $z->getName() . " ";
echo $traitObj->getName() . ":\r\n";
echo $traitObj->getDocComment() . "\r\n";
}
Carlos Alberto Bertholdo Carucce ¶
8 years ago
If you want to resolve name conflicts and also change the visibility of a trait method, you'll need to declare both in the same line:
trait testTrait{
public function test(){
echo 'trait test';
}
}
class myClass{
use testTrait {
testTrait::test as private testTraitF;
}
public function test(){
echo 'class test';
echo '<br/>';
$this->testTraitF();
}
}
$obj = new myClass();
$obj->test(); //prints both 'trait test' and 'class test'
$obj->testTraitF(); //The method is not accessible (Fatal error: Call to private method myClass::testTraitF() )
katrinaelaine6 at gmail dot com ¶
7 years ago
Adding to "atorich at gmail dot com":
The behavior of the magic constant __CLASS__ when used in traits is as expected if you understand traits and late static binding (http://php.net/manual/en/language.oop5.late-static-bindings.php).
<?php
$format = 'Class: %-13s | get_class(): %-13s | get_called_class(): %-13s%s';
trait TestTrait {
public function testMethod() {
global $format;
printf($format, __CLASS__, get_class(), get_called_class(), PHP_EOL);
}
public static function testStatic() {
global $format;
printf($format, __CLASS__, get_class(), get_called_class(), PHP_EOL);
}
}
trait DuplicateTrait {
public function duplMethod() {
global $format;
printf($format, __CLASS__, get_class(), get_called_class(), PHP_EOL);
}
public static function duplStatic() {
global $format;
printf($format, __CLASS__, get_class(), get_called_class(), PHP_EOL);
}
}
abstract class AbstractClass {
use DuplicateTrait;
public function absMethod() {
global $format;
printf($format, __CLASS__, get_class(), get_called_class(), PHP_EOL);
}
public static function absStatic() {
global $format;
printf($format, __CLASS__, get_class(), get_called_class(), PHP_EOL);
}
}
class BaseClass extends AbstractClass {
use TestTrait;
}
class TestClass extends BaseClass { }
$t = new TestClass();
$t->testMethod();
TestClass::testStatic();
$t->absMethod();
TestClass::absStatic();
$t->duplMethod();
TestClass::duplStatic();
?>
Will output:
Class: BaseClass | get_class(): BaseClass | get_called_class(): TestClass
Class: BaseClass | get_class(): BaseClass | get_called_class(): TestClass
Class: AbstractClass | get_class(): AbstractClass | get_called_class(): TestClass
Class: AbstractClass | get_class(): AbstractClass | get_called_class(): TestClass
Class: AbstractClass | get_class(): AbstractClass | get_called_class(): TestClass
Class: AbstractClass | get_class(): AbstractClass | get_called_class(): TestClass
Since Traits are considered literal "copying/pasting" of code, it's clear how the methods defined in DuplicateTrait give the same results as the methods defined in AbstractClass.
84td84 at gmail dot com ¶
9 years ago
A note to 'Beispiel #9 Statische Variablen'. A trait can also have a static property:
trait Counter {
static $trvar=1;
public static function stfunc() {
echo "Hello world!"
}
}
class C1 {
use Counter;
}
print "\nTRVAR: " . C1::$trvar . "\n"; //prints 1
$obj = new C1();
C1::stfunc(); //prints Hello world!
$obj->stfunc(); //prints Hello world!
A static property (trvar) can only be accessed using the classname (C1).
But a static function (stfunc) can be accessed using the classname or the instance ($obj).
artur at webprojektant dot pl ¶
12 years ago
Trait can not have the same name as class because it will show: Fatal error: Cannot redeclare class
