How to use and introduce the PHP Closure class

This article mainly introduces how to use the PHP Closure class. Interested friends can refer to it. I hope it will be helpful to everyone.

Closure, anonymous functions, also known as Anonymous functions, were introduced in php5.3. Anonymous function is a function without a defined name. Keep this in mind and you will be able to understand the definition of anonymous functions.

Closure class (PHP 5 >= 5.3.0) Introduction to the class used to represent anonymous functions. Anonymous functions (introduced in PHP 5.3) will generate objects of this type. Let's take a look at PHP How to use and introduce the Closure class.

PHP Closure class was introduced before in PHP predefined interface, but it is not an interface, it is an internal final class. The Closure class is used to represent anonymous functions, and all anonymous functions are instances of the Closure class.

$func = function() {
  echo 'func called';
};
var_dump($func); //class Closure#1 (0) { }
$reflect =new ReflectionClass('Closure');
var_dump(
  $reflect->isInterface(), //false
  $reflect->isFinal(), //true
  $reflect->isInternal() //true
);

The Closure class structure is as follows:

Closure::__construct — Constructor used to prohibit instantiation
Closure::bind — Copy a closure, Binds the specified $this object to the class scope.
Closure::bindTo — Copies the current closure object and binds the specified $this object and class scope.

Look at an example of binding $this object and scope:

class Lang
{
  private $name = 'php';
}
$closure = function () {
  return $this->name;
};
$bind_closure = Closure::bind($closure, new Lang(), 'Lang');
echo $bind_closure(); //php

In addition, PHP uses the magic method __invoke() to turn a class into a closure:

class Invoker {
  public function __invoke() {return __METHOD__;}
}
$obj = new Invoker;
echo $obj(); //Invoker::__invoke

Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study.

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