1     public function build($concrete)
 2     {
 3         // If the concrete type is actually a Closure, we will just execute it and
 4         // hand back the results of the functions, which allows functions to be
 5         // used as resolvers for more fine-tuned resolution of these objects.
 6         //若传入的是一个闭包则直接通过闭包实例化类，这种闭包一般由provider类在laravel应用初始化阶段通过bind方法进行绑定。
 7         if ($concrete instanceof Closure) {
 8             return $concrete($this, $this->getLastParameterOverride());
 9         }
10         //制造一个类反射
11         $reflector = new ReflectionClass($concrete);
12 
13         // If the type is not instantiable, the developer is attempting to resolve
14         // an abstract type such as an Interface of Abstract Class and there is
15         // no binding registered for the abstractions so we need to bail out.
16         if (! $reflector->isInstantiable()) {
17             return $this->notInstantiable($concrete);
18         }
19         //将当前所实例化的类存入栈
20         $this->buildStack[] = $concrete;
21         //获得该类构造方法
22         $con