php - 什么是 PHP 匿名函数？

Question

PHP 中的匿名函数是什么？请给我一个简单的例子好吗？

Answer 1

PHP.net 有一个关于 Anonymous functions 的手册页在维基百科上，您可以阅读有关 Anonymous functions 的信息一般而言。

Anonymous functions can be used to contain functionality that need not be named and possibly for short-term use. Some notable examples include closures.

来自 PHP.net 的示例

<?php
$greet = function($name)
{
    printf("Hello %s\r\n", $name);
};

$greet('World');
$greet('PHP');
?>

PHP 4.0.1 至 5.3

$foo = create_function('$x', 'return $x*$x;');
$bar = create_function("\$x", "return \$x*\$x;");
echo $foo(10);

PHP 5.3

$x = 3;
$func = function($z) { return $z *= 2; };
echo $func($x); // prints 6

PHP 5.3 does support closures but the variables must be explicitly indicated

$x = 3;
$func = function() use(&$x) { $x *= 2; };
$func();
echo $x; // prints 6

示例取自维基百科和 php.net