php Trait基类use trait,本类不use
一 回顾trait使用https://blog.csdn.net/bushuwei/article/details/103514174
发现之前本人说明很模糊，自己居然不知道为什么
其实这里的$c,就是class B
再次回顾逻辑
二 分析
[*]self和static区别说的没毛病
[*]Trait基类use trait,本类不use。那么如果用的new self，则你new 出来的就是 use trait者。如果new static，则因为有继承关系， 它会判断类是否存在(父子会被认为都是同一个static，则不再new)，那么，谁先调用instance，那么new出来的就是谁。‘Trait基类use trait,本类不use’->直接‘其实这里的$c,就是class B’是错的。之所以有这个‘幻觉’，是因为单例模式，且static
三 上代码
[*]self+单例
trait A{
private static $instance;
static function getInstance()
{
if(!isset(self::$instance)){
self::$instance = new self();
}
return self::$instance;
}
}
class B{
use A;
function a()
{
var_dump('call at B');
}
}
class C extends B{
function a()
{
var_dump('call at c');
parent::a();
}
}
class D extends B{
use A;
function a()
{
var_dump('call at D');
parent::a();
}
}
$b = B::getInstance();
$c = C::getInstance();
$d = D::getInstance();
$c->a();
echo "<br/>";
$d->a();
echo "<br/>";
string(9) "call at B"
string(9) "call at D" string(9) "call at B" 注视掉
// $b = B::getInstance();<br>结果不变
[*]static+单例
trait A{
private static $instance;
static function getInstance()
{
if(!isset(self::$instance)){
self::$instance = new static();
}
return self::$instance;
}
}
class B{
use A;
function a()
{
var_dump('call at B');
}
}
class C extends B{
function a()
{
var_dump('call at c');
parent::a();
}
}
class D extends B{
use A;
function a()
{
var_dump('call at D');
parent::a();
}
}
$b = B::getInstance();
$c = C::getInstance();
$d = D::getInstance();
$c->a();
echo "<br/>";
$d->a();
echo "<br/>";string(9) "call at B"
string(9) "call at D" string(9) "call at B"
注视掉
// $b = B::getInstance();string(9) "call at c" string(9) "call at B"
string(9) "call at D" string(9) "call at B"
[*] self+非单例
trait A{
private static $instance;
static function getInstance()
{
self::$instance = new self();
return self::$instance;
}
}
class B{
use A;
function a()
{
var_dump('call at B');
}
}
class C extends B{
function a()
{
var_dump('call at c');
parent::a();
}
}
class D extends B{
use A;
function a()
{
var_dump('call at D');
parent::a();
}
}
$b = B::getInstance();
$c = C::getInstance();
$d = D::getInstance();
$c->a();
echo "<br/>";
$d->a();
echo "<br/>";
string(9) "call at B"
string(9) "call at D" string(9) "call at B" 注释掉
// $b = B::getInstance();结果不变
[*] static+非单例
trait A{
private static $instance;
static function getInstance()
{
// if(!isset(self::$instance)){
// self::$instance = new static();
// }
// return self::$instance;
self::$instance = new static();
return self::$instance;
}
}
class B{
use A;
function a()
{
var_dump('call at B');
}
}
class C extends B{
function a()
{
var_dump('call at c');
parent::a();
}
}
class D extends B{
use A;
function a()
{
var_dump('call at D');
parent::a();
}
}
$b = B::getInstance();
$c = C::getInstance();
$d = D::getInstance();
$c->a();
echo "<br/>";
$d->a();
echo "<br/>";
string(9) "call at c" string(9) "call at B"
string(9) "call at D" string(9) "call at B" 注释掉
$b = B::getInstance();
结果不变
四 结论
[*]self的话，就是谁use的，就是谁
[*]static的话，谁调用的就是谁
[*]但是static会出现‘谁use就是谁’的幻觉，那是因为单例模式，前面创建了相同类型的单例。
来源:https://www.cnblogs.com/bushuwei/p/17277267.html
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