Interface interface in PHP

* Interface

* 1. Use keyword: interface

* 2. A class is a template for an object, and an interface is a template for a class

* 3. The interface is considered a special class

* 4. Methods in the interface, only declarations are not implemented, as with abstract classes

* 5. The method in the interface must be public, support the static

* 6. The class constant const can be declared in the interface, but is not allowed to be overridden by a class or sub-interface

* 7. Use the Implements keyword to implement an interface with a class

* 8. A class can implement multiple interfaces, with multiple interfaces separated by commas

* 9. You can also use keyword extends to inherit between interfaces

* 10. A method cannot have a duplicate name when a class is actually multiple interfaces

Declaration Interface: Animal

if (!interface_exists (' Animal ')) {interface Animal {//interface constant Const STATUS = ' viable ';//Can Survive    Interface method: What to eat when feeding public function feeding ($foods);                }}//declares class cat and implements Interface Animalif (interface_exists (' Animal ')) {class Cat implements Animal {private $name = ' cat '; The method in the interface must be implemented in the class feeding () Public function feeding ($foods) {return $this->name. '        Eat '. $foods; }}//instantiate the Dog class, Echo (New Cat ())->feeding (' mouse '), echo ' 
Instantiation of the Dog class

Echo (New Dog ())->feeding (' meat '); Echo (new Dog ())->hobby (' Loyal, brave, never abandon ~ ~ ');
Let's think about how to change the above two method calls to a chain?

Note: The above instantiation Call statement is commented out first, otherwise the following chained call does not take effect

(New Dog)->feeding (' Bones ')->hobby (', cute, docile, obedient ~ ~ ');