douyi2798 2015-06-15 19:32
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你如何在PHP中的类中使用匿名函数?

How do I call $greet inside this class? I am using PHP 5.5.4.

<?PHP   
class Model
{
    public $greet = function($name)
    {
        printf("Hello %s
", $name);
    };
}

$test = new Model();
$test->greet('World');
$test->greet('PHP');
?>

Parse error: syntax error, unexpected '$greet' (T_VARIABLE), expecting function (T_FUNCTION)

Also tried this,

$test = new Model();
call_user_func($test->greet('World'));
call_user_func($test->greet('PHP')) 

The anonymous function works fine outside the class (straight from the manual).

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

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

EDIT: I took out the dollar signs, in my call (I caught it just as an answer started to roll in. It did not help,

call_user_func($test->greet('World'));
call_user_func($test->greet('PHP'));

EDIT:

class Model
{
    public $greet;
    function __construct()
    {
        $this->greet = function($name)
        {
            printf("Hello %s
", $name);
        };
    }
}

$test = new Model();
$test->greet('johnny');

Now I get,

Fatal error: Call to undefined method Model::greet() 
  • 写回答

2条回答 默认 最新

  • dongying6179 2015-06-15 21:03
    关注

    The fact that you call greet makes PHP treat it like a function and not a property. You can have the same name for both a property and method in PHP, so the distinction is relevant.

    What you can doe as a workaround is use the __call() magic method. It will catch the call to the undefined greet method.

    class Model
    {
        public $greet;
        function __construct()
        {
            $this->greet = function($name)
            {
                printf("Hello %s
    ", $name);
            };
        }
    
        function __call($method, $args)
        {
            if (isset($this->$method) && $this->$method instanceof \Closure) {
                return call_user_func_array($this->$method, $args);
            }
    
            trigger_error("Call to undefined method " . get_called_class() . '::' . $method, E_USER_ERROR);
        }
    }
    
    $test = new Model();
    $test->greet('johnny');
    

    Update for PHP7

    In PHP7 the __call() method is no longer needed to call closures bound to properties, because of Uniform Variable Syntax. This will allow you to add parentheses around any code, just like you do in arithmetics.

    class Model
    {
        public $greet;
        function __construct()
        {
            $this->greet = function($name)
            {
                printf("Hello %s
    ", $name);
            };
        }
    }
    
    $test = new Model();
    ($test->greet)('johnny');
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论
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