What is the function of make method in laravel

In laravel, the make method is used to parse a type from the container. The type is defined in the source code. The result returned after parsing is an instance of the type. When the container class calls the make method, if there is no The registered key will automatically instantiate the concrete class through the reflection class.

#The operating environment of this article: Windows 10 system, Laravel version 6, Dell G3 computer.

What is the role of the make method in laravel

The make method in Laravel is used to parse a type from the container. This type is defined in the source code and is not easy to translate into Chinese. The result returned after parsing is an instance of type.

Students who have read the source code should know that there is a make method in the Illuminate\Foundation\Application class and its parent class Illuminate\Container\Container class. Then when executing this line of code in index.php ,

1 $kernel = $app->make(Illuminate\Contracts\Http\Kernel::class);

, it will first execute Illuminate\Foundation\Application make method, so let's take a look at it first. (This article takes the make Kernel class as an example)

     /**
      * Resolve the given type from the container. 从容器当中解析给定的type
      *
      * (Overriding Container::make) 覆盖了父类中的make方法
      *
      * @param  string  $abstract 给定的type
      * @param  array  $parameters 指定一些参数 可选项
      * @return mixed
      */
     public function make($abstract, array $parameters = [])
     {
         $abstract = $this->getAlias($abstract);//调用父类中的getAlias方法
 　　　　　//如果在deferredServices这个数组设置了这个type并且在instances数组中没有设置这个type
         if (isset($this->deferredServices[$abstract]) && ! isset($this->instances[$abstract])) {
             $this->loadDeferredProvider($abstract);//那么就执行这个方法：加载被定义为延迟的服务提供者
       }
 
         return parent::make($abstract, $parameters);//调用父类的make方法
     }

Okay, let’s go step by step. First, let’s take a look at the getAlias ​​method. The function of this method is to return the alias of this class. If given If it is a complete class name and has been set in aliases, then the alias of the class name will be returned. If it has not been set, the class name itself will be returned. When looking at this method, you can var_dump $app first and compare it. The aliases array inside, the framework author wrote this method is really clever, at least this recursive method is rarely used in my actual development.

    /**
      * Get the alias for an abstract if available.
     *
     * @param  string  $abstract
     * @return string
    *
     * @throws \LogicException
     */
    public function getAlias($abstract)
    {
         if (! isset($this->aliases[$abstract])) {
            return $abstract;
         }
 
        if ($this->aliases[$abstract] === $abstract) {
            throw new LogicException("[{$abstract}] is aliased to itself.");
        }
        return $this->getAlias($this->aliases[$abstract]);
     }

The next step is to judge the two arrays of deferredServices and instances. In this example, $kernel = $app->make(Illuminate\Contracts\Http\Kernel::class); The result is false, so the loadDeferredProvider method is not executed.

The next step is to call the make method in the parent class Illuminate\Container\Container,

     /**
      * Resolve the given type from the container.
      *
      * @param  string  $abstract
      * @param  array  $parameters
      * @return mixed
     */
     public function make($abstract, array $parameters = [])
     {
      return $this->resolve($abstract, $parameters);//直接调用resolve方法
 }

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