How to use php Closure class

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.

PHP Closure class was introduced before in PHPPredefined 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 function used to prohibit instantiation
Closure::bind — Copy a closure and bind 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 methodinvoke() to turn a class into a closure:

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

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