PHP learning private properties of external calling classes

This article mainly talks about the private properties of external calling classes, which has certain reference value. Interested friends can learn about it and hope to help you.

Private attributes of external calling classes

First let’s take a look at the __get and __set functions in the PHP class
When trying to get an unavailable When the attribute is reached, the class will automatically call the __get function.
When trying to set an unreachable property, the class will automatically call the __set function.

First, let’s take a look at the __get function. Let’s try to get a reachable attribute:

<?php
    class A{
        public $a=1;
        private $b=2;
        function __get($name){
            echo &#39;you can get &#39;.$name;
        }
    }
    $dy = new A();
    echo $dy->a;
?>

Look at its return:

1

No problem, the __get function is not called. Now I will access a private unreachable attribute:

<?php
    class A{
        public $a=1;
        private $b=2;
        function __get($name){
            echo &#39;you can get &#39;.$name;
        }
    }
    $dy = new A();
    echo $dy->b;
?>

and I will find:

you can get b

It means __get is called here function, let me take a look at the __set function, which also uses the reachable public attribute first:

<?php
    class A{
        public $a;
        private $b;
        function __set($name,$val){
            echo &#39;you can get &#39;.$name.$val;
        }
    }
    $dy = new A();
    $dy->a = 1;
    echo $dy->a;
?>

Look at the output:

1

Used successfully, no problem, then we use private attributes:

<?php
    class A{
        public $a;
        private $b;
        function __set($name,$val){
            echo &#39;you can get &#39;.$name.$val;
        }
    }
    $dy = new A();
    $dy->b = 1;
    echo $dy->b;
?>

At this time we see:

you can get b1

PHP Fatal error:  Cannot access private property A::$b in /usercode/file.php on line 11

The __set function is called here and prompts us that we cannot use it Private properties of the class.
Now let’s use the __set function to implement external use of private attributes:

<?php
    class A{
        public $a;
        private $b;
        function __set($name,$val){
                $this->$name=$val;
        }
        function B(){
            echo $this->b;
        }
    }
    $dy = new A();
    $dy->b = 1;
    $dy->B();
?>

Look at the output:

1

It means the use is successful.

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