PHP - 如何解决“不在对象上下文中使用 $this”的错误？
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PHP - How to solve error "using $this when not in object context"?
提问by Christopher
I've this trait class:
我有这个特质类：
trait Example
{
protected $var;
private static function printSomething()
{
print $var;
}
private static function doSomething()
{
// do something with $var
}
}
And this class:
而这个类：
class NormalClass
{
use Example;
public function otherFunction()
{
$this->setVar($string);
}
public function setVar($string)
{
$this->var = $string;
}
}
But i'm getting this error:
Fatal error: Using $this when not in object context.
但我收到此错误：
Fatal error: Using $this when not in object context。
How can i solve this issue? I can't use properties on a trait class? Or this isn't really a good practice?
我该如何解决这个问题？我不能在 trait 类上使用属性？或者这真的不是一个好习惯？
回答by Dmitrii Cheremisin
Your problem is connected with differences between class's methods/properties and object's.
您的问题与类的方法/属性和对象之间的差异有关。
- If you define propertie as static - you should obtain it through your class like classname/self/parent::$propertie.
- If not static - then inside static propertie like $this->propertie. So, you may look at my code:
- 如果您将属性定义为静态 - 您应该通过像 classname/self/parent::$properie 这样的类来获取它。
- 如果不是静态的 - 那么在静态属性中，如 $this->propertie。所以，你可以看看我的代码：
trait Example
{
protected static $var;
protected $var2;
private static function printSomething()
{
print self::$var;
}
private function doSomething()
{
print $this->var2;
}
}
class NormalClass
{
use Example;
public function otherFunction()
{
self::printSomething();
$this->doSomething();
}
public function setVar($string, $string2)
{
self::$var = $string;
$this->var2 = $string2;
}
}
$obj = new NormalClass();
$obj -> setVar('first', 'second');
$obj -> otherFunction();
Static function printSomething can't access not static propertie $var! You should define them both not static, or both static.
静态函数printSomething不能访问非静态属性$var！你应该定义它们都不是静态的，或者都是静态的。
