Detailed introduction to the difference between the constructor _construct() and _initialize() of classes in ThinkPHP

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

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.

Looking at the code today, I suddenly saw _construct()This construction method that comes with PHP. My first impression was that it was relatively unfamiliar, although I often used it when learning Java before. Encountered it, but haven’t used it for a long time and basically forgotten it. 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(){

}
}

?>

in the subclass SonAction The output result is: <div class="code" style="position:relative; padding:0px; margin:0px;"><pre class='brush:php;toolbar:false;'>son</pre><div class="contentsignin">Copy after login</div></div>

<?php


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

　　}
}

?>

fatherson

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

When we change the above construction method to the

method, we will find that the result is the same as the previous one Consistently, 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 PHP comes with it? Is the constructor

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(){

　　}

}

?>

That is The subclass called the constructor of the parent class, but did not call the

method of the subclass

<?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;;
　　}
}

?>

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).

Summarize

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