每天laravel-20160801| Container -4

    /**     * Register a binding with the container.     * Register a binding with the container.     * @param  string|array  $abstract     * @param  \Closure|string|null  $concrete     * @param  bool  $shared     * @return void     */    public function bind($abstract, $concrete = null, $shared = false)    {// bind abstract con        $abstract = $this->normalize($abstract);// get the right normalize        $concrete = $this->normalize($concrete);// get the right concrete        // If the given types are actually an array, we will assume an alias is being        // defined and will grab this "real" abstract class name and register this        // alias with the container so that it can be used as a shortcut for it.        // now i say,if they give us a array use a types.        // so we need do something for it,        // if the "real" abstract class name is too long,        // we can use alias to defined the real class name as a shortcut name.        if (is_array($abstract)) {// check the abstract name is a array            list($abstract, $alias) = $this->extractAlias($abstract);// a array one is abstract , other is alias            $this->alias($abstract, $alias);// return the result to the alias.        }        // If no concrete type was given, we will simply set the concrete type to the        // abstract type. This will allow concrete type to be registered as shared        // without being forced to state their classes in both of the parameter.        // i coming ,if never give us a concrete type class, we will use a abstract type.        // so they will be registered as shared .        // no forced to state their classes in both of the parameter        $this->dropStaleInstances($abstract);// then can drop the state Instances.        if (is_null($concrete)) {            $concrete = $abstract;        }// if the concrete is null        // 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 the instance of concrete not a Closure.        // so it means it just a class name be used bound to a container.        // may be it is a abstract type .        // so we can use that self own Closure to wrap it.        // to give us more function when it extending        if (! $concrete instanceof Closure) {            $concrete = $this->getClosure($abstract, $concrete);        }// get the Closure, more like hook        $this->bindings[$abstract] = compact('concrete', 'shared');// a 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 the class name is ready resolved in the container.        // so we will fire the rebound listener .        // so that any objects which have already gotten resolved can have their copy        // via the listener callbacks        if ($this->resolved($abstract)) {// has the resolved            $this->rebound($abstract);// set the rebound        }    }// too long too not simple