Laravel 原始碼筆記 容器 alias 方法

概念

類的別名

註冊的型別別名
protected $aliases = [];
以抽象名稱為鍵的已註冊別名
protected $abstractAliases = [];

原始碼

class Application >

public function __construct($basePath = null)
{
    // 在容器中註冊核心(core)類別名
    $this->registerCoreContainerAliases();
}
---------------------------------------------------------------------------
public function registerCoreContainerAliases()
{
        foreach ([
            'app'=> [self::class, \Illuminate\Contracts\Container\Container::class, \Illuminate\Contracts\Foundation\Application::class,  \Psr\Container\ContainerInterface::class],
            'auth' => [\Illuminate\Auth\AuthManager::class, \Illuminate\Contracts\Auth\Factory::class],
            ...
        ] as $key => $aliases) {
            foreach ($aliases as $alias) {
                $this->alias($key, $alias);
            }
        }
}
--------------------------------------------------------------------------
class Container >

public function alias($abstract, $alias)
{
    $this->aliases[$alias] = $abstract;

    $this->abstractAliases[$abstract][] = $alias;
}
---------------------------------------------------------------------------

列印後

--------------------------------------------------------------------
#aliases: array:64 [
    "Illuminate\Foundation\Application" => "app"
    "Illuminate\Contracts\Container\Container" => "app"
    "Illuminate\Contracts\Foundation\Application" => "app"
    "Psr\Container\ContainerInterface" => "app"
    "Illuminate\Auth\AuthManager" => "auth"
    "Illuminate\Contracts\Auth\Factory" => "auth"
    ...
]
-------------------------------------------------------------------
#abstractAliases: array:34 [
    "app" => array:4 [
        0 => "Illuminate\Foundation\Application"
        1 => "Illuminate\Contracts\Container\Container"
        2 => "Illuminate\Contracts\Foundation\Application"
        3 => "Psr\Container\ContainerInterface"
    ]
    "auth" => array:2 [
        0 => "Illuminate\Auth\AuthManager"
        1 => "Illuminate\Contracts\Auth\Factory"
    ]
    ...
]
--------------------------------------------------------------------

總結

alias() 相對簡單，通過這個方法的原始碼，可發現幾個特點：

1. 屬性$aliases 與屬性 $abstractAliases 是鍵值對相反的，是互相對應的。
2. $aliases 中可以通過實現類以及它所實現的契約類任何一個找到相同的別名。反之，在 $abtractAliases 中通過別名可找到類名及它所實現的契約類。

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