PHP $ this不在对象上下文中来自类外的set public变量

I have simple class and I want to set public variable from out of class.

我有简单的类,我想从课外设置公共变量。

<?php

class AlachiqHelpers
{
    public $height;

    public static function getHeight($height)
    {
        return $this->height - 50;
    }

    public static function setHeight($height)
    {
        $this->height = $height;
    }
}

In Result i get this error:

在结果中我收到此错误:

Using $this when not in object context

3 个解决方案

#1

The $this keyword cannot be used under static context !.

Case 1:

You need to remove the static keyword from the function defintion.

您需要从函数定义中删除static关键字。

Instead of

public static function setHeight( $height ){

Should be

public function setHeight( $height ){

---

Case 2:

If you really need to make it(function) as static... You could just use the self keyword to access the variable..

如果你真的需要将它(函数)作为静态...你可以使用self关键字来访问变量..

public static $height;
public static function setHeight( $height )
{
    self::$height=22;
}

Keep in mind that the $height variable is also made static

请记住,$ height变量也是静态的

---

The working code.. (static one)

<?php
class AlachiqHelpers
{
    public static $height;
    public function getHeight()
    {
        return self::$height - 50;
    }

    public static function setHeight($height1)
    {
        self::$height = $height1;
    }
}

$a = new AlachiqHelpers();
$a->setHeight(180);
echo $a->getHeight();

OUTPUT :

130

#2

Remove static, these methods should not be static method but instance method.

删除静态,这些方法不应该是静态方法而是实例方法。

$this can not be used under static context, because static context is shared by all the instances but not a single one.

$ this不能在静态上下文中使用,因为静态上下文由所有实例共享,但不是单个实例共享。

Static method can only access the static property.

静态方法只能访问静态属性。

Non-static method can access both non-static property (by $this->foo) and static property(by self::$foo).

非静态方法可以访问非静态属性(通过$ this-> foo)和静态属性(通过self :: $ foo)。

#3

Source

Because static methods are callable without an instance of the object created, the pseudo-variable $this is not available inside the method declared as static.

因为静态方法可以在没有创建对象实例的情况下调用,所以伪变量$ this在声明为static的方法中不可用。

You can't use $this inside a static function, because static functions are independent of any instantiated object.

你不能在静态函数中使用$ this,因为静态函数独立于任何实例化对象。

Try making the function not static.

尝试使该功能不是静态的。

public  function setHeight( $height ){

        $this->height=$height;

    }