《PHP實(shí)例:PHP中trait使用方法詳細(xì)介紹》要點(diǎn):
本文介紹了PHP實(shí)例:PHP中trait使用方法詳細(xì)介紹,希望對(duì)您有用。如果有疑問(wèn),可以聯(lián)系我們。
PHP實(shí)例說(shuō)通俗點(diǎn),PHP中使用trait關(guān)鍵字是為了解決一個(gè)類既想集成基類的屬性和方法,又想擁有別的基類的方法,而trait一般情況下是和use搭配使用的.
PHP實(shí)例
<?php
trait Drive {
public $carName = 'trait';
public function driving() {
echo "driving {$this->carName}\n";
}
}
class Person {
public function eat() {
echo "eat\n";
}
}
class Student extends Person {
use Drive;
public function study() {
echo "study\n";
}
}
$student = new Student();
$student->study();
$student->eat();
$student->driving();
?>
PHP實(shí)例輸出結(jié)果如下:
PHP實(shí)例
study
eat
driving trait
PHP實(shí)例上面的例子中,Student類通過(guò)繼承Person,有了eat方法,通過(guò)組合Drive,有了driving方法和屬性carName.
PHP實(shí)例如果Trait、基類和本類中都存在某個(gè)同名的屬性或者方法,最終會(huì)保留哪一個(gè)呢?
PHP實(shí)例
<?php
trait Drive {
public function hello() {
echo "hello drive\n";
}
public function driving() {
echo "driving from drive\n";
}
}
class Person {
public function hello() {
echo "hello person\n";
}
public function driving() {
echo "driving from person\n";
}
}
class Student extends Person {
use Drive;
public function hello() {
echo "hello student\n";
}
}
$student = new Student();
$student->hello();
$student->driving();
?>
PHP實(shí)例輸出結(jié)果如下:
PHP實(shí)例
hello student
driving from drive
PHP實(shí)例因此得出結(jié)論:當(dāng)方法或?qū)傩酝麜r(shí),當(dāng)前類中的方法會(huì)覆蓋 trait的 方法,而 trait 的方法又覆蓋了基類中的方法.
PHP實(shí)例如果要組合多個(gè)Trait,通過(guò)逗號(hào)分隔 Trait名稱:
PHP實(shí)例
use Trait1, Trait2;
PHP實(shí)例如果多個(gè)Trait中包含同名方法或者屬性時(shí),會(huì)怎樣呢?答案是當(dāng)組合的多個(gè)Trait包含同名屬性或者方法時(shí),需要明確聲明解決沖突,否則會(huì)產(chǎn)生一個(gè)致命錯(cuò)誤.
PHP實(shí)例
<?php
trait Trait1 {
public function hello() {
echo "Trait1::hello\n";
}
public function hi() {
echo "Trait1::hi\n";
}
}
trait Trait2 {
public function hello() {
echo "Trait2::hello\n";
}
public function hi() {
echo "Trait2::hi\n";
}
}
class Class1 {
use Trait1, Trait2;
}
?>
PHP實(shí)例輸出結(jié)果如下:
PHP實(shí)例使用insteadof和as操作符來(lái)解決沖突,insteadof是使用某個(gè)方法替代另一個(gè),而as是給方法取一個(gè)別名,具體用法請(qǐng)看代碼:
PHP實(shí)例
<?php
trait Trait1 {
public function hello() {
echo "Trait1::hello\n";
}
public function hi() {
echo "Trait1::hi\n";
}
}
trait Trait2 {
public function hello() {
echo "Trait2::hello\n";
}
public function hi() {
echo "Trait2::hi\n";
}
}
class Class1 {
use Trait1, Trait2 {
Trait2::hello insteadof Trait1;
Trait1::hi insteadof Trait2;
}
}
class Class2 {
use Trait1, Trait2 {
Trait2::hello insteadof Trait1;
Trait1::hi insteadof Trait2;
Trait2::hi as hei;
Trait1::hello as hehe;
}
}
$Obj1 = new Class1();
$Obj1->hello();
$Obj1->hi();
echo "\n";
$Obj2 = new Class2();
$Obj2->hello();
$Obj2->hi();
$Obj2->hei();
$Obj2->hehe();
?>
PHP實(shí)例輸出結(jié)果如下:
PHP實(shí)例
Trait2::hello
Trait1::hi
Trait2::hello
Trait1::hi
Trait2::hi
Trait1::hello
PHP實(shí)例as關(guān)鍵詞還有另外一個(gè)用途,那就是修改方法的訪問(wèn)控制:
PHP實(shí)例Trait 也能組合Trait,Trait中支持抽象方法、靜態(tài)屬性及靜態(tài)方法,測(cè)試代碼如下:
PHP實(shí)例
<?php
trait Hello {
public function sayHello() {
echo "Hello\n";
}
}
trait World {
use Hello;
public function sayWorld() {
echo "World\n";
}
abstract public function getWorld();
public function inc() {
static $c = 0;
$c = $c + 1;
echo "$c\n";
}
public static function doSomething() {
echo "Doing something\n";
}
}
class HelloWorld {
use World;
public function getWorld() {
return 'get World';
}
}
$Obj = new HelloWorld();
$Obj->sayHello();
$Obj->sayWorld();
echo $Obj->getWorld() . "\n";
HelloWorld::doSomething();
$Obj->inc();
$Obj->inc();
?>
PHP實(shí)例輸出結(jié)果如下:
PHP實(shí)例
Hello
World
get World
Doing something
1
2
PHP實(shí)例以上就是本文的全部?jī)?nèi)容,希望對(duì)大家的學(xué)習(xí)有所幫助,也希望大家多多支持維易PHP.
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