PHP 回调、匿名函数和闭包

<?php
class Product{
public $name;
public $price;

function __construct($name, $price){
$this->name = $name;
$this->price = $price;
}
}

class ProcessSale{
private $callbacks;

function registerCallback($callback){
if(!is_callable($callback)){
throw new Exception("callback not callable");
}
$this->callbacks[] = $callback;
}

function sale($product){
print "{$product->name}:processing \n";
foreach ($this->callbacks as $callback){
call_user_func($callback, $product);
}
}
}

$logger = create_function('$product', 'print "   logging ({$product->name})\n";');

$processor = new ProcessSale();
$processor->registerCallback($logger);

$processor->sale(new Product("shoes", 6));
print "\n";
$processor->sale(new Product("coffee", 6));

$logger2 = function($product){
print "  logging ({$product->name})\n";
};

$processor = new ProcessSale();

$processor = new ProcessSale();
$processor->registerCallback($logger2);

$processor->sale(new Product("shoes", 6));
print "\n";
$processor->sale(new Product("coffee", 6));

class Mailer{
function doMail($product){
print "  mailing ({$product->name})\n";
}
}

$processor = new ProcessSale();
$processor->registerCallback(array(new Mailer(), "doMail"));

$processor->sale(new Product("shoes", 6));
print "\n";
$processor->sale(new Product("coffee", 6));

class Totalizer{
static function warnAmount(){
return function($product){
if ($product->price > 5){
print "  reached high price: {$product->price}\n";
}
};
}
}

$processor = new ProcessSale();
$processor->registerCallback(Totalizer::warnAmount());

//.....

class TotalizerNew{
static function warnAmount($amt){
$count = 0;
return function($product) use ($amt, &$count){
$count += $product->price;
print "  count: $count\n";
if ($count > $amt){
print "  high price reached:{$count}\n";
}
};
}
}

$processor = new ProcessSale();
$processor->registerCallback(TotalizerNew::warnAmount(8));

$processor->sale(new Product("shoes", 6));
print "\n";
$processor->sale(new Product("coffee", 6));