源码问题请教

$str = 'abc';

(function($s){
    var_dump($s);
})($str); // 1. 输出 abc

$fun1 = function($s){
    var_dump($s);
};
$fun1($str); // 2. 输出 abc
// 这里把 $fun1 换成上面的 function 再加个括号，就变成第一种

function fun2()
{
  return function ($param1) {
      var_dump($param1);
  };
}
fun2()($str); // 3. 输出 abc (是不是跟 $container 有一点点相似了)

// 常规函数声明
function funX($s){
    var_dump($s);
};
funX($str); // x. 输出 abc （常规方法）
Copy

$closure = function($container, $abc){ };
return $closure;

// 调用闭包
$closure($app)Copy

$bindings = [
    'key' =>[
         'concrete' =>  Closure,
         'shared' => false //而 singleton() 时为 true
    ]
]Copy

$this->app->bind(Test::class, function ($app) {
    return new Test($app->make(Test2::class));
});Copy

/**
     * Register a binding with the container.
     *
     * @param  string  $abstract
     * @param  \Closure|string|null  $concrete
     * @param  bool  $shared
     * @return void
     *
     * @throws \TypeError
     */
    public function bind($abstract, $concrete = null, $shared = false)
    {
        $this->dropStaleInstances($abstract);

        // If no concrete type was given, we will simply set the concrete type to the
        // abstract type. After that, the concrete type to be registered as shared
        // without being forced to state their classes in both of the parameters.
        if (is_null($concrete)) {
            $concrete = $abstract;
        }

        // If the factory is not a Closure, it means it is just a class name which is
        // bound into this container to the abstract type and we will just wrap it
        // up inside its own Closure to give us more convenience when extending.
        if (! $concrete instanceof Closure) {
            if (! is_string($concrete)) {
                throw new TypeError(self::class.'::bind(): Argument #2 ($concrete) must be of type Closure|string|null');
            }

            $concrete = $this->getClosure($abstract, $concrete);
        }

        $this->bindings[$abstract] = compact('concrete', 'shared');

        // If the abstract type was already resolved in this container we'll fire the
        // rebound listener so that any objects which have already gotten resolved
        // can have their copy of the object updated via the listener callbacks.
        if ($this->resolved($abstract)) {
            $this->rebound($abstract);
        }
    }

    /**
     * Get the Closure to be used when building a type.
     *
     * @param  string  $abstract
     * @param  string  $concrete
     * @return \Closure
     */
    protected function getClosure($abstract, $concrete)
    {
        return function ($container, $parameters = []) use ($abstract, $concrete) {
            if ($abstract == $concrete) {
                return $container->build($concrete);
            }

            return $container->resolve(
                $concrete, $parameters, $raiseEvents = false
            );
        };
    }Copy