Define a class with a variable name in PHP?

Question

I am wanting to be able to do something to the order of this

$name = "Hello".time().mt_rand();
class $name {
    function hellolol() {
        echo "LOL";
    }
}
$name::hellolol();

So that I can build a reload-able module system in PHP. Is this even possible, and if so, how would I go about doing something like this?

EDIT: I've since turned this into a project that essentially does what the accepted answer suggested. Here's a link: https://github.com/Modfwango/Modfwango

Why is that necessary to build a "reload-able module system"? What is a "reload-able module system"? — Ry-
– Ry- ♦, Commented Nov 22, 2012 at 2:06
Since you cannot redefine classes, I need to be able to have a dynamic name for the class. This will allow me to include a file, initialize the function, and register the classname in a module management class. — Clay Freeman
– Clay Freeman, Commented Nov 22, 2012 at 2:07
@ClayFreeman: Why do you need a dynamic name, though? Why do you even need separate classes? — Ry-
– Ry- ♦, Commented Nov 22, 2012 at 2:11
@ClayFreeman: Sorry, not specific enough :) I really don't see how that changes anything. Do you mean you want to update a file and include it again? (How are you running PHP in such a way that that's even possible?) — Ry-
– Ry- ♦, Commented Nov 22, 2012 at 2:18

chelmertz · Accepted Answer · 2012-11-22 02:12:22Z

4

$name = "Hello".time().mt_rand();
eval(sprintf('
class %s {
    static function hellolol() {
        echo "LOL";
    }
}', $name));
$name::hellolol();

Pretty nasty but good for mocking, etc.

answered Nov 22, 2012 at 2:12

chelmertz

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5 Comments

Clay Freeman Over a year ago

This should work, and I appreciate the answer, but I am weary that this will show up horribly in my text editor.

chelmertz Over a year ago

It probably will. Trick it by using a template, place the content in a .php file with the definition class @@CLASSNAME@@ and use eval(str_replace('@@CLASSNAME@@', $class_name, file_get_contents('your_template.php')));

Clay Freeman Over a year ago

I am probably going to end up doing that.

Adam Over a year ago

Looks familiar! Keep in mind that eval parses the given string as though it's already prefixed by <?php, so you'll need to use eval('?>'.[...] if the template file starts with <?php

chelmertz Over a year ago

@Adam: did you invent sed as well? ^^ I just saw this eval-method in the wild, check out Kohana2's autoloader. I'm gonna be sick..

Adam · Accepted Answer · 2012-11-22 02:14:28Z

3

This technically is possible, just in a very, very bad way.

First, save this file:

<?php
// GeneratedClass.php
class CLASSNAME {
    function hellolol(){
        echo "LOL";
    }
}

Then, use the following to create classes with custom names:

<?php
function generate_class($name){
    eval('?>'.str_replace('CLASSNAME', $name, file_get_contents('GeneratedClass.php')));
}

generate_class("Hello".time().mt_rand());

Again, this is not a good idea! Aside from the fact that anything to do with eval is probably a bad idea, by parsing these classes manually, you'd lose any advantages an IDE would give you, the files wouldn't be cacheable by something like memcached, and it's just altogether a nightmare to use. But it's possible.

answered Nov 22, 2012 at 2:14

Adam

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5 Comments

Clay Freeman Over a year ago

I like this answer. This may be how I set this up. I am going to use something to this nature to make a reload-able module system for an IRC bot. This will allow me to instantiate new classes for commands when they are reloaded so that I won't have to restart the whole process for minor changes to things.

Adam Over a year ago

Hopefully it works for you! A long time ago I had a similar setup to this going to let me override classes throughout an application, or generate a class if the override didn't exist...I've since realised that wasn't a good idea, and come up with better ways to go about it, so make sure it's the best option for what you're trying to achieve!

Clay Freeman Over a year ago

I hope this works. I think that it will work for me. I will throw away the old classes when they are old, etc.

Adam Over a year ago

If the classes you're generating are going to be used more than once, consider saving them to a file instead of evaling, so then you can include them like normal, and save having to reload the original generation file each time.

Clay Freeman Over a year ago

Generation will be part of the class for managing the modules that I load.

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