The role of php closures

<code>    public function __construct($config)
    {
    parent::__construct();
    $this['config'] = function () use ($config) {
        return new Config($config);
    };
    ...
    其中
    $this['config'] = function () use ($config) {
        return new Config($config);
    能不能直接写成这样：
    $this['config'] = new Config($config);
    有什么优势？</code>

Reply content:

<code>    public function __construct($config)
    {
    parent::__construct();
    $this['config'] = function () use ($config) {
        return new Config($config);
    };
    ...
    其中
    $this['config'] = function () use ($config) {
        return new Config($config);
    能不能直接写成这样：
    $this['config'] = new Config($config);
    有什么优势？</code>

Lazy loading. Both ways of writing are fine, however.
$this['config'] = new Config($config);
In this way, when you assign a value to $this->['config'], new Config($ config)operation.

$this['config'] = function () use ($config) {
        return new Config($config);
}

In this way, you just give $this->['config'] an anonymous function, and when you want to use it, you will perform the new Config($config) operation.

I don’t know if my explanation is correct= =It’s not very expressive= =

<code>能不能直接写成这样：
$this['config'] = new Config($config);
有什么优势？</code>

It can be written like this, but it will go to the new Config class every time it is instantiated, and it does not matter whether it is used or not;

<code>$this['config'] = function () use ($config) {
        return new Config($config);
}</code>

This way of writing is to declare an anonymous function for $this['config']. When $this['config'] is actually called, the new Config class will be accessed;

The advantage of writing like this is that when $this['config'] is not actually used, it reduces the additional instantiation process and memory consumption

closure will create a new Config when it is actually called, so that lazy load can be achieved.

In addition to the above lazy loading, another advantage is that it implements a factory mode -- every time you get the config, it will be new

1. Lazy loadingEveryone has mentioned it

2. In fact, anonymous functions are largely a manifestation of functional programming