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I like to spend time studying how frameworks are coded in attempt to better my code.

As far as I know the Scope Resolution Operator in PHP calls a function in a class as a static function, meaning that you do not have access to '$this' because the class hasn't been instantiated.

But when I started reading up how the Laravel 4 Auth works I noticed that the documentation tells you to use Auth::check() or Auth::user() to retrieve information, yet the code in those functions is using many '$this' statements.

Can anyone explain to me how they are able to retrieve the instance properties if the functions are being called as static methods?

Here is the link to the github raw file for Laravel Auth

https://raw.githubusercontent.com/illuminate/auth/master/Guard.php

bertmaclin
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2 Answers2

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Laravel uses a development pattern known as Facades and Inversion of Control (IoC) in order to take static calls to some objects (the 'Facade') and retrieve an actual instance of an object (from the IoC container) to call the method on.

Put another way, when you do Auth::check() and Auth::user() those seemingly static calls get replaced with actual object instances from within the IoC container, so Auth::check() becomes $auth->check() with $auth being derived from within the container.

This allows you to 1) Write Auth::check() instead of $auth = new Auth; $auth->check() and 2) let the IoC container do all of the dirty work around actually creating the instance you want, so if implementation details change later you don't have to rewrite any code that uses the Auth class.

See this documentation page about facades and this question about IoC in general for more information.

As a side note, the Auth facade referred to in Auth::check() et al is actually this class: https://github.com/laravel/framework/blob/master/src/Illuminate/Support/Facades/Auth.php

Community
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Jeff Lambert
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  • Brilliant. Thank you. I have an app which I developed in Codeigniter. I'd love to port it to Laravel but that would be super time consuming. I love Laravels auth system and was thinking of trying to port it over. Thank you very much – bertmaclin May 20 '14 at 21:54
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It's a Fcade.

When you're calling Auth::{anything}, you're actually calling Illuminate\Support\Facades\Auth. The static method is only used as an entry point.

This is a simplified version of the Facade design pattern:
http://sourcemaking.com/design_patterns/facade/php

c-griffin
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