Analyze the usage of __initialize() and class constructor __construct() in ThinkPHP

This article analyzes __initialize() and the class constructor __construct() in ThinkPHP with examples. Share it with everyone for your reference. The specific analysis is as follows:

__construct in thinkphp cannot be used casually, because your module class inherits the superior class, and the superior class is defined;

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1. __initialize() is not a function in the php class. The constructor of the php class is only __construct() .

2. Class initialization: If the subclass has its own constructor (__construct()), it will call its own for initialization. If not, it will call the parent class's constructor for its own initialization.

3. When both the subclass and the parent class have the __construct() function, if you want to call the parent class's __constrcut() at the same time when initializing the subclass, you can Use parent::__construct().

in subclasses. If we write two classes, as follows:

The code is as follows:

class Action{  
    public function __construct()  
    {  
        echo 'hello Action';  
    }  
}  
class IndexAction extends Action{  
    public function __construct()  
    {  
        echo 'hello IndexAction';  
    }  
}  
$test = new IndexAction;  
//output --- hello IndexAction

Obviously, when initializing the subclass IndexAction, it will call its own constructor, so the output is 'hello IndexAction', but modify the subclass to:

The code is as follows:

class IndexAction extends Action{  
    public function __initialize()  
    {  
        echo 'hello IndexAction';  
    }  
}

Then the output is 'hello Action', because the subclass IndexAction does not have its own constructor. What if I want to call the constructor of the parent class at the same time when initializing the subclass?

The code is as follows:

class IndexAction extends Action{  
    public function __construct()  
    {  
        parent::__construct();  
        echo 'hello IndexAction';  
    } 
    }

In this way, two sentences can be output at the same time. Of course, another way is to call the method of the subclass in the parent class.

The code is as follows:

class Action{  
    public function __construct()  
    {  
        if(method_exists($this,'hello'))  
        {  
            $this -> hello();  
        }  
        echo 'hello Action';  
    }  
}  
class IndexAction extends Action{  
    public function hello()  
    {  
        echo 'hello IndexAction';  
    }  
}

In this way, two sentences can also be output at the same time, and the method hello() in the subclass here is similar to __initialize() in ThinkPHP.

So, the appearance of __initialize() in ThinkPHP is just to facilitate programmers to avoid frequent use of parent::__construct() when writing subclasses. At the same time Correctly call the constructor of the parent class in the framework. Therefore, when we initialize the subclass in ThnikPHP, we must use __initialize() instead of __construct(). Of course, you can also modify the framework to _ Change the _initialize() function to the function name you like.

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