This article mainly introduces the detailed explanation of the usage of closure in php. Friends who need it can refer to it
This article mainly introduces the detailed explanation of the usage of closure in php. Friends who need it can refer to it
Closure, anonymous function, was introduced in php5.3, also known as Anonymous functions. The literal meaning is a function without a defined name. For example, the following code (the file name is do.php)
<?php
function A() {
return 100;
};
function B(Closure $callback)
{
return $callback();
}
$a = B(A());
print_r($a);//输出：Fatal error: Uncaught TypeError: Argument 1 passed to B() must be an instance of Closure, integer given, called in D:\web\test\do.php on line 11 and defined in D:\web\test\do.php:6 Stack trace: #0 D:\web\test\do.php(11): B(100) #1 {main} thrown in D:\web\test\do.php on line 6
?>A() here can never be used as a parameter of B, because A is not "Anonymous" functions.
So it should be changed to this:
<?php
$f = function () {
return 100;
};
function B(Closure $callback)
{
return $callback();
}
$a = B($f);
print_r($a);//输出100
<?
$func = function( $param ) {
echo $param;
};
$func( 'hello word' );
//输出：hello word##Implement closure
Pass anonymous functions as parameters in ordinary functions, and they can also be returned. This implements a simple closure. I will give three examples below:<?php
//例一
//在函数里定义一个匿名函数，并且调用它
function printStr() {
$func = function( $str ) {
echo $str;
};
$func( ' hello my girlfriend ! ' );
}
printStr();//输出 hello my girlfriend !
//例二
//在函数中把匿名函数返回，并且调用它
function getPrintStrFunc() {
$func = function( $str ) {
echo $str;
};
return $func;
}
$printStrFunc = getPrintStrFunc();
$printStrFunc( ' do you love me ? ' );//输出 do you love me ?
//例三
//把匿名函数当做参数传递，并且调用它
function callFunc( $func ) {
$func( ' no!i hate you ' );
}
$printStrFunc = function( $str ) {
echo $str.'<br>';
};
callFunc( $printStrFunc );
//也可以直接将匿名函数进行传递。如果你了解js，这种写法可能会很熟悉
callFunc( function( $str ) {
echo $str; //输出no!i hate you
} );<?php
function getMoney() {
$rmb = 1;
$dollar = 8;
$func = function() use ( $rmb ) {
echo $rmb;
echo $dollar;
};
$func();
}
getMoney();
//输出：1<?php
function getMoney() {
$rmb = 1;
$func = function() use ( $rmb ) {
echo $rmb.'<br>';
//把$rmb的值加1
$rmb++;
};
$func();
echo $rmb;
}
getMoney();
//输出：
//1
//1<?php
function getMoney() {
$rmb = 1;
$func = function() use ( &$rmb ) {
echo $rmb.'<br>';
//把$rmb的值加1
$rmb++;
};
$func();
echo $rmb;
}
getMoney();
//输出：
//1
//2<?php
function getMoneyFunc() {
$rmb = 1;
$func = function() use ( &$rmb ) {
echo $rmb.'<br>';
//把$rmb的值加1
$rmb++;
};
return $func;
}
$getMoney = getMoneyFunc();
$getMoney();
$getMoney();
$getMoney();
//输出：
//1
//2
//3<?php
class A {
public static function testA() {
return function($i) { //返回匿名函数
return $i+100;
};
}
}
function B(Closure $callback)
{
return $callback(200);
}
$a = B(A::testA());
print_r($a);//输出 300The concept of binding
The Closure in the above example is just a global anonymous function. Okay, now we want to specify a class There is an anonymous function. It can also be understood that the access scope of this anonymous function is no longer global, but the access scope of a class. Then we need to bind "an anonymous function to a class".<?php
class A {
public $base = 100;
}
class B {
private $base = 1000;
}
$f = function () {
return $this->base + 3;
};
$a = Closure::bind($f, new A);
print_r($a());//输出 103
echo PHP_EOL;
$b = Closure::bind($f, new B , 'B');
print_r($b());//输出1003(PHP 5 >= 5.4.0, PHP 7)
This method is Closure::bindTo( ) static version. Check out its documentation for more information.
<?php
class A {
private static $sfoo = 1;
private $ifoo = 2;
}
$cl1 = static function() {
return A::$sfoo;
};
$cl2 = function() {
return $this->ifoo;
};
$bcl1 = Closure::bind($cl1, null, 'A');
$bcl2 = Closure::bind($cl2, new A(), 'A');
echo $bcl1(), "\n";//输出 1
echo $bcl2(), "\n";//输出 2<?php
class A {
public $base = 100;
}
class B {
private $base = 1000;
}
class C {
private static $base = 10000;
}
$f = function () {
return $this->base + 3;
};
$sf = static function() {
return self::$base + 3;
};
$a = Closure::bind($f, new A);
print_r($a());//这里输出103,绑定到A类
echo PHP_EOL;
$b = Closure::bind($f, new B , 'B');
print_r($b());//这里输出1003，绑定到B类
echo PHP_EOL;
$c = $sf->bindTo(null, 'C'); //注意这里：使用变量#sf绑定到C类，默认第一个参数为null
print_r($c());//这里输出10003<?php
/**
* 复制一个闭包，绑定指定的$this对象和类作用域。
*
* @author fantasy
*/
class Animal {
private static $cat = "加菲猫";
private $dog = "汪汪队";
public $pig = "猪猪侠";
}
/*
* 获取Animal类静态私有成员属性
*/
$cat = static function() {
return Animal::$cat;
};
/*
* 获取Animal实例私有成员属性
*/
$dog = function() {
return $this->dog;
};
/*
* 获取Animal实例公有成员属性
*/
$pig = function() {
return $this->pig;
};
$bindCat = Closure::bind($cat, null, new Animal());// 给闭包绑定了Animal实例的作用域，但未给闭包绑定$this对象
$bindDog = Closure::bind($dog, new Animal(), 'Animal');// 给闭包绑定了Animal类的作用域，同时将Animal实例对象作为$this对象绑定给闭包
$bindPig = Closure::bind($pig, new Animal());// 将Animal实例对象作为$this对象绑定给闭包,保留闭包原有作用域
echo $bindCat(),'<br>';// 输出：加菲猫，根据绑定规则，允许闭包通过作用域限定操作符获取Animal类静态私有成员属性
echo $bindDog(),'<br>';// 输出：汪汪队, 根据绑定规则，允许闭包通过绑定的$this对象(Animal实例对象)获取Animal实例私有成员属性
echo $bindPig(),'<br>';// 输出：猪猪侠, 根据绑定规则，允许闭包通过绑定的$this对象获取Animal实例公有成员属性<?php
/**
* 给类动态添加新方法
*
* @author fantasy
*/
trait DynamicTrait {
/**
* 自动调用类中存在的方法
*/
public function __call($name, $args) {
if(is_callable($this->$name)){
return call_user_func($this->$name, $args);
}else{
throw new \RuntimeException("Method {$name} does not exist");
}
}
/**
* 添加方法
*/
public function __set($name, $value) {
$this->$name = is_callable($value)?
$value->bindTo($this, $this):
$value;
}
}
/**
* 只带属性不带方法动物类
*
* @author fantasy
*/
class Animal {
use DynamicTrait;
private $dog = '汪汪队';
}
$animal = new Animal;
// 往动物类实例中添加一个方法获取实例的私有属性$dog
$animal->getdog = function() {
return $this->dog;
};
echo $animal->getdog();//输出 汪汪队<?php
/**
* 一个基本的购物车，包括一些已经添加的商品和每种商品的数量
*
* @author fantasy
*/
class Cart {
// 定义商品价格
const PRICE_BUTTER = 10.00;
const PRICE_MILK = 30.33;
const PRICE_EGGS = 80.88;
protected $products = array();
/**
* 添加商品和数量
*
* @access public
* @param string 商品名称
* @param string 商品数量
*/
public function add($item, $quantity) {
$this->products[$item] = $quantity;
}
/**
* 获取单项商品数量
*
* @access public
* @param string 商品名称
*/
public function getQuantity($item) {
return isset($this->products[$item]) ? $this->products[$item] : FALSE;
}
/**
* 获取总价
*
* @access public
* @param string 税率
*/
public function getTotal($tax) {
$total = 0.00;
$callback = function ($quantity, $item) use ($tax, &$total) {
$pricePerItem = constant(__CLASS__ . "::PRICE_" . strtoupper($item)); //调用以上对应的常量
$total += ($pricePerItem * $quantity) * ($tax + 1.0);
};
array_walk($this->products, $callback);
return round($total, 2);
}
}
$my_cart = new Cart;
// 往购物车里添加商品及对应数量
$my_cart->add('butter', 10);
$my_cart->add('milk', 3);
$my_cart->add('eggs', 12);
// 打出出总价格，其中有 3% 的销售税.
echo $my_cart->getTotal(0.03);//输出 1196.4Usage of anonymous functions and closures (closure) in php
Introduction to phpclosureUsage examples
Detailed explanation of Closure class in PHP
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