I read about the PHP Implementation of LINQ called PHPLinq. Frankly, I was sceptical about it. Finally, I gave it a try. I still remain sceptical... Let me explain why. Take a look at this fairly simple example, where we extract all the numbers greater than 5:

<?php

set_include_path(get_include_path() . PATH_SEPARATOR . '../PhpLinq/Classes/');
require_once('PHPLinq/LinqToObjects.php');

$numbers = array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

$result = from('$number')->in($numbers)
            ->where('$number => $number > 5')
            ->select('$number');

print_r($result);           

?>

If you familiar with LINQ, then you may say: "Wow, that’s cool! Just like in .NET". Yes, the syntax is quite familiar. But if you look closer, you will notice that the query expressions are encloced in single quotes, i.e. they are just string. That makes a significant difference between PHPLinq and real LINQ. Do you remember what LINQ stands for? It stands for Language Intergrated Query. Unfortunately, PHPLinq isn’t a language integrated query, since it’s not supported by the language natively and we have to use strings for writting queries.

When we write real LINQ queries in Visual Studio we’ve got syntax highlighting, we’ve got IntelliSence and that is more important we can track errors at the compilation stage. PHPLinq lacks all these things. Ok, PHP is an interpreted language, so there’s no compilation stage; however there are smart IDEs that track errors while we’re writing code.

I want to illistrate this, let’s make a deliberate error, we’ll change $number to $number1 in the from clause. If you run the script you’ll get a notice, in case notices are enabled and nothing more.But if you are writing this in C#, it won’t even get compiled.

In the real world LINQ is used mostly as a SQL replace, we don’t have to write the queries in strings anymore and catch the exceptions when running an application. But unfortunately we cannot do the same with PHPLinq, it still forces us to put the queries into strings.

Well, I think I was sceptical enough about it, but still PHPLinq has some cool features, just check this example taken from the PHPLinq official web site:

<?php
/**
 * PHPLinq
 *
 * Copyright (c) 2008 PHPLinq
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * @category   PHPLinq
 * @package    PHPLinq
 * @copyright  Copyright (c) 2008 PHPLinq (http://www.codeplex.com/PHPLinq)
 * @license    http://www.gnu.org/licenses/lgpl.txt    LGPL
 * @version    0.3.0, 2008-06-23
 */

/** Error reporting */
error_reporting(E_ALL);

/** Include path **/
set_include_path(get_include_path() . PATH_SEPARATOR . '../Classes/');

/** PHPLinq_LinqToObjects */
include 'PHPLinq/LinqToObjects.php';

// Custom class
class Employee {
    public $Name;
    public $Email;
 
    public function __construct($name, $email) {
        $this->Name     = $name;
        $this->Email     = $email;
    }
}

// Create data source
$rssFeed = simplexml_load_string(file_get_contents('http://blog.maartenballiauw.be/syndication.axd'));
$result = from('$item')->in($rssFeed->xpath('//channel/item'))
            ->orderByDescending('$item => strtotime((string)$item->pubDate)')
            ->take(2)
            ->select('new {
                            "PostTitle" => (string)$item->title,
                            "PostAuthor" => (string)$item->author,
                            "MetaData" => new {
                                                "Url" => (string)$item->link,
                                                "Guid" => (string)$item->guid,
                                                "PostDate" => strtotime((string)$item->pubDate)
                                          }
                      }');
               
print_r($result); 

What do you think?