如何在启动应用程序中自动创建类的单个实例

Question

I have class with my logic.

class BlogApp

   class BlogApp
   {
    public static $app;

    public function __construct()
    {
        self::$app = Registry::instance();
        $this->getParams();
    }

class Registry

   class Registry
   {
    use TSingletone;

    protected static $properties = [];

    public function setProperty($name, $value)
    {
        self::$properties[$name] = $value;
    }

    public function getProperty($name)
    {
        if (isset(self::$properties[$name])) {
            return self::$properties[$name];
        }
        return null;
    }

    public function getProperties()
    {
        return self::$properties;
    }

I want to use my class BlogApp { } anywhere in the controllers to store properties. For example

    BlogApp::$app->setProperty('img_width', 1280);

    $wmax = BlogApp::$app->getProperty('img_width');

and my public/index.php

    new \App\BlogApp();

but I have exception

    Call to a member function getProperty() on null

if I use this one

    $d = new BlogApp();
    $d::$app->getProperty('img_width');

No problem. But I want

   $wmax = BlogApp::$app->getProperty('img_width');

where is my mistake ?

Answer 1

You are creating an object of the Registry within constructor in BlogApp class, so to call the getProperty method, you have to need to create an object of BlogApp.

However, if you want to call the getProperty function with a reference to the class, then don't create an instance of Registry in the BlogApp constructor.

class BlogApp
{
    public static $app;

    // Create a function call get_instance 
    public static function get_instance()
    {
        // create instance of Registry class
        self::$app = Registry::instance();
        self::getParams();

        return self::$app;
    }
}

/*
* Call the getProperty funtion with reference of class.
* 1 - Object of the Registry is Creating When you call the static function get_instance.
* 2 - Once the object is created you can call the getProperty function.
*/
$wmax = BlogApp::get_instance()->getProperty('img_width');