PHP: How to create and register class at runtime

Question

Is there any official/recommended way to declare/define/register a new class at runtime in PHP?

What I basically want to do is generating Classes based on the definition stored in a database, both properties and methods.

I have found some article/threads, but all of them are actually old, so I was wondering if it exists some elegant/efficient way to do it. My surprise is that there is no so much information about this as I thought.

Is it so bad? As far as I know, PHP always saves the class definition in memory so I don't see any problem in declaring the class at runtime as it's basically the same result, but maybe I'm wrong.

I think is not relevant right now, but I'm working with Laravel in this project.

Thanks!

Josh · Accepted Answer · 2016-05-03 18:35:49Z

3

Yes.

<?php

$foobar = "foobar";

eval("class $foobar {" .
        "function __construct(\$i) {" .
                "echo \"Dark magic ritual complete. \$i virgins sacrificed to satan.\"; " .
        "}" . 
" }");

$evil = new $foobar(5);


echo "<br /><br />";

var_dump($evil);

Produces:

Dark magic ritual complete. 5 virgins sacrificed to satan.

object(foobar)#1 (0) { }

I'm not going to lecture you on semantics, but this is a terribly bad idea and you should reconsider using classes to facilitate what the database records need. A class by itself is not special, but using a class to handle a database entry is perfectly acceptable.

answered May 3, 2016 at 18:35

Josh

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13 Comments

dbf Over a year ago

I think he is creating classes based on values stored in the database, not something equivalent as ORM.

Josh Over a year ago

Either I need a lot more caffeine or "declare/define/register" has a different meaning to me. It's trivial to instantiate a new, which would indicate he wants something more complicated.

Desproposito Over a year ago

Thanks for your answer. What I actually need is to work with dynamic entities, as the different users should be able to create their own objects with its attributes. I have decided not to use Entity-Attribute-Value "anti"-pattern because of the complexity and all the cons it has, so I thought this could be a better solution. I tried to ask which was the best approach/pattern for this in another question but It didn't work as it was not a Php specifc question. So, which would be the recommendation for this?

Josh Over a year ago

As I've shown, you can use new $foobar where $foobar is a class name to instantiate an existing class. In an anecdotal experience, I've had a User Password table where a user's password could have many different kinds of encryption algorithms. To solve password checking, I wrote a Password interface and then PasswordMd5 PasswordSha256 classes that implement the Interface and instantiate based on a complementary encryption column. $goodPassword = new $encryption()->is($inputPassword).

Josh Over a year ago

That question, by the way, is the one you should have been asking. :P

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