Think about the difference between class constructor _construct() and _initialize() in PHP

This article mainly introduces the difference between the constructor _construct() and _initialize() of the class in ThinkPHP. The introduction in the article is very detailed. I believe it has certain reference value for everyone. Friends who need it can read it together. Take a look.

Preface

I believe that phpers who are familiar with THINKPHP are basically familiar with _initialize()This method, we seem to also _construct() is rarely used, unless you write a plug-in yourself, otherwise it is really rarely used.

When I was checking the code today, I suddenly saw _construct(). This construction method that comes with PHP was unfamiliar to me at first. Although I often encountered it when I was learning Java before, I haven’t used it for a long time. Basically forgotten. My usual habit is to write the key points of knowledge in my small notebook, but I haven’t written for a long time, and the elegant and smart writing style I used in high school has completely disappeared into another dimension. In addition to the previous thoughts, I came to learn how to write blogs from technology experts. This is not to show off, but just to prevent every bit of the results of my work from dissipating with the passage of time. Let’s take a look at the detailed introduction below.

First paste the code (my environment is wamp, using the TP framework):

<?php


class FatherAction extends Action{
　　public function __construct(){
　　　　echo &#39;father&#39;;
　　}
}

?>

<?php


class SonAction extends FatherAction{
　　public function __construct(){
　　　　echo &#39;son&#39;;
　　}
function index(){

}
}

?>

Run

in the subclass SonAction and you can see the output:

son

<?php


class SonAction extends FatherAction{
　　　public function __construct(){
　　　　parent::__construct();
　　　　echo &#39;son&#39;;
　　　}
　　function index(){

　　}
}

?>

fatherson

The above results can be concluded: The parent class will not be automatically called when the constructor of the subclass is executed. If you want to call the constructor, then add

When we change the above constructor method to

When running the method, you will find that the result is consistent with the previous one. If you want to execute the _initialize() method of the parent class, you also need to use this sentence: parent::_initialize() Does that mean that the constructor

that comes with PHP is the same as the _initialize() method of THINKPHP?

<?php


class FatherAction extends Action{
　　public function __construct(){
　　　　echo &#39;father&#39;;
　　}
}

?>

<?php


class SonAction extends FatherAction{
　　public function _initialize(){
　　　　echo &#39;son&#39;;
　　}


　　function index(){

　　}

}

?>

When executing the index method of the subclass SonAction, it is found that the output result is: father

That is, the subclass calls the constructor of the parent class without calling the subclass's

Method

<?php


class FatherAction extends Action{
　　public function __construct(){
　　　　if(method_exists($this,"hello")){
　　　　　　$this->hello();
　　　　}
　　　　echo &#39;father&#39;;
　　}
}

?>

<?php


class SonAction extends FatherAction{
　　public function _initialize(){
　　　　echo &#39;son&#39;;
　　}
　　function index(){

　　}

　　function hello(){
　　　　echo &#39;hello&#39;;
　　}
}

?>

Execute the index method of the subclass SonAction and find that the input result is hellofather

From this we can draw the conclusion: When THINKPHP When the parent class has a constructor but the subclass does not, THINKPHP will not execute the subclass's

； When THINKPHP's parent class and subclasses both have constructors, it must be called The constructor of the parent class must use

----------------- _initialize()Similarly; When a subclass of THINKPHP has both the

constructor and the _initialize() method, only the __construct constructor of the subclass will be executed (this is my Personal test, the above code does not work). Related recommendations:

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