PHP中将对象方法或闭包作为回调函数传递的实践指南

<?php

function executeCallback($callback) {
    if (is_callable($callback)) {
        $callback();
    } else {
        echo "Error: Provided argument is not callable.\n";
    }
}

// 直接传递一个匿名函数作为回调
executeCallback(function() {
    echo "This is a direct closure callback.\n";
});

?>

<?php

// 这是一个期望回调函数的函数
function ex($callback){
   $callback();
}

// 创建一个stdClass对象，并将一个闭包赋值给其属性'f'
$obj = (object) ['f' => function(){echo "hello from closure property!\n";}];

// 将存储在对象属性中的闭包作为回调传递
// $obj->f 本身就是一个可调用（callable）的闭包
ex($obj->f);

// 尝试像调用方法一样调用属性中的闭包会导致错误
// $obj->f(); // Fatal error: Uncaught Error: Call to undefined method stdClass::f()

// 正确地直接调用存储在属性中的闭包
// 方式一：通过括号明确其为可调用变量
($obj->f)();

// 方式二：先赋值给变量再调用
$func = $obj->f;
$func();

?>

<?php

function ex($callback){
   $callback();
}

class Example {
  public static function f_static() {
    echo "This is a static method call.\n";
  }
}

// 将静态方法作为回调传递
ex(['Example', 'f_static']);

?>

<?php

function ex($callback){
   $callback();
}

class Example {
  public function f_instance() {
    echo "This is an instance method call.\n";
  }
}

$e = new Example();

// 将实例方法作为回调传递
ex([$e, 'f_instance']);

?>

<?php

function processCallback($callback) {
    if (is_callable($callback)) {
        echo "Executing callback: ";
        $callback();
    } else {
        echo "Invalid callback provided.\n";
    }
}

// 1. 直接传递匿名函数（闭包）
processCallback(function() {
    echo "Hello from direct closure.\n";
});

// 2. 将闭包存储在对象属性中并传递
$objWithClosure = (object) ['myFunc' => function() {
    echo "Hello from closure in object property.\n";
}];
processCallback($objWithClosure->myFunc);

// 3. 传递静态方法
class MyClass {
    public static function staticMethod() {
        echo "Hello from static method.\n";
    }

    public function instanceMethod() {
        echo "Hello from instance method.\n";
    }
}
processCallback(['MyClass', 'staticMethod']);

// 4. 传递实例方法
$myInstance = new MyClass();
processCallback([$myInstance, 'instanceMethod']);

?>

Executing callback: Hello from direct closure.
Executing callback: Hello from closure in object property.
Executing callback: Hello from static method.
Executing callback: Hello from instance method.