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 'you can get '.$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 'you can get '.$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,$val){ echo 'you can get '.$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,$val){ echo 'you can get '.$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.
Related tutorials: PHP video tutorial
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