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In PHP 7, a new feature, spaceship operator has been introduced. It is used to compare two expressions. It returns -1, 0 or 1 when first expression is respectively less than, equal to, or greater than second expression.

 <?php
print( 1 <=> 1);print("
");
    print( 1 <=> 2);print("
");
    print( 2 <=> 1);print("
");
?>
  

In PHP 7, a new feature, null coalescing operator (??) has been introduced. It is used to replace the ternary operation in conjunction with isset() function. The Null coalescing operator returns its first operand if it exists and is not NULL; otherwise it returns its second operand.

Closures are anonymous functions that are declared inline and assigned to a variable. It can be used as a callback for later execution. In PHP 5 it was already possible to bind an object to the scope of the closure as if it was a method.

The “call” method is one of the PHP 7 features that was introduced to simplify the process.

<?php
     /**
      * Closure::call()
      */
     class PHPCode {
         private $foo = 'PHPCode';
     }
     
     $getFooCallback = function() {
         return $this->foo;
     };

     echo $getFooCallback->call(new PHPCode);

Anonymous classes are useful for simple one-off objects. With anonymous classes you can define a class and instantiate an object inline.

<?php
 /**
 Anonymous classes
 */ 
 $anonymousClassObject = new class {
     public function test() {
         return "PHPCodez";
     }
 };
 echo $anonymousClassObject->test();

Whereas type hints ensure input consistency, return type declarations ensure output consistency.

We use a colon before the opening curly brace of a function to hint the return type.

The same strictness rules apply as with the type hints: if “strict mode” is disabled, return values that can be converted to the preferred type are allowed. If you enable “strict mode” this code will throw a type error.