About the implementation of singleton pattern in PHP

Since I used to do java development, when using the singleton mode, the first thing I thought of was to use the hungry Chinese style, and then I found that in PHP, there is such a feature: because PHP does not support giving the class when the class is defined. Member variables are assigned values ​​of non-basic types. Such as expressions, new operations, etc. Instead, I wanted to ensure the atomicity of this singleton mode, and found that there are no thread safety issues in PHP like in JAVA.

Hey, do you think PHP is good? OK, then let’s try PHP’s lazy singleton mode.

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1. Three private and one public:

①. Private static attributes, Then store the unique object generated

②, private constructor

③, private clone function to prevent cloning - clone

④, public static method for access Objects stored in static attributes. If there is no object, this singleton is generated

2. Keyword instanceof

Check whether this variable is an object or subclass of this class , or implement the interface.

1. A private __construct is necessary. A singleton class cannot be instantiated in other classes, but can only be instantiated by itself;

2. Having an instance of a saved class Static member variables;

3. A static public method is used to instantiate this class and access instances of this class;

  class SingleInstance{
        
        private function _construct(){
            
        }
        
       private static $instance;
       
       private function _clone(){
           
       }
       public static function getInstance(){
           
           if(!self::$instance instanceof SingleInstance){
               self::$instance=new SingleInstance();
           }
           return self ::$instance;
           
       }
       
    }

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