Cannot redeclare requireDependencies()

[RobIsHere]

Hi!

I get the following error sometimes. Somehow this is loaded twice. I installed with composer and I'm using the default autoloader and no manual require statements at all. So I have no idea how this can happen.

Cannot redeclare requireDependencies() (previously declared in libs/braintree/braintree_php/lib/Braintree.php:17) in libs/braintree/braintree_php/lib/Braintree.php:17

[juongithub]

Probably you are including twice the initialization script, how do you load the "autoload.php" script?

[RobIsHere]

I should be protected from that if everything is working right here. That's what autoload does. Check if class XY exists yet and load it if it doesn't.

I have a lot of libraries included. Also e.g. all of laravel 5.1., mail service etc. That libraries work without errors.

[juongithub]

I think you are loading the library in the wrong way, or there was an error during the installation... I see the directory tree:

│   autoload.php   
├───bin       
├───braintree
│   └───braintree_php   
│       ├───lib
│       │   │   autoload.php
│       │   │   Braintree.php
│       [...]   
├───composer
├───phpunit         
├───symfony
└───vlucas

and I include the "autoload.php" in the root of the tree. Everything works fine for me.

[RobIsHere]

I will investigate a little on this and get back to you. As I see this we need more information to get to a valid conclusion.

[RobIsHere]

I extracted a minimal example that fails on the second "is_subclass_of".

<?php
include("vendor/autoload.php");

class XYZ {}
class ABC {}

if (is_subclass_of('Braintree', 'XYZ')) echo "subclass of xyz";
if (is_subclass_of('Braintree', 'ABC')) echo "subclass of abc";

Exception:

PHP Fatal error:  Cannot redeclare requireDependencies() (previously declared in /root/projects/braintest/vendor/braintree/braintree_php/lib/Braintree.php:16) in /root/projects/braintest/vendor/braintree/braintree_php/lib/Braintree.php on l
ine 23                                                                                                                                                                                                                                          
PHP Stack trace:                                                                                                                                                                                                                                
PHP   1. {main}() /root/projects/braintest/test.php:0                                                                                                                                                                                           
PHP   2. is_subclass_of() /root/projects/braintest/test.php:8                                                                                                                                                                                   
PHP   3. spl_autoload_call() /root/projects/braintest/test.php:8                                                                                                                                                                                
PHP   4. Composer\Autoload\ClassLoader->loadClass() /root/projects/braintest/test.php:8                                                                                                                                                         
PHP   5. Composer\Autoload\includeFile() /root/projects/braintest/vendor/composer/ClassLoader.php:322                                                                                                                                           

Tested on PHP 5.6.30 and 7.
braintest.tar.gz

[juongithub]

Braintree is not a class, but the root namespace. With those line of codes you are forcing the "autoloader" to load the file Braintree.php that does not contain any class definition. You will see the same error with these lines:

include("vendor/autoload.php");
echo class_exists( 'Braintree' );
echo class_exists( 'Braintree' );

these lines do not cause the error:

include("vendor/autoload.php");
echo class_exists( 'Braintree\Configuration' );
echo class_exists( 'Braintree\Configuration' );

It is an irrelevant issue since you never need to instantiate Braintree (that is not a class and therefore cannot be instantiated). However, if you want to solve this just add:

class Braintree {}

anywhere in Braintree.php.

[RobIsHere]

Omg! Is it so hard to wrap this "requireDependencies" in function_exists?

Yes this Issue has 3 Sources:

1. I made a const PAYMENT_PROVIDER
2. Rethinkdb has maybe a Bug checking is_subclass_of of everything including
3. You have a Bug because you are not following the psr autoloader specifications! That you are defining a function there is simply NOT ALLOWED!

class User {
    const PAYMENT_PROVIDER = 'Braintree';
    ....
}

Saving the user with rethinkdb in a totally unrelated area does the is_subclass check for every property
https://github.com/danielmewes/php-rql

[RobIsHere]

I fixed the Issue in my code. For me there is no problem anymore. All others saving something with the name "Braintree" on it using rethinkdb will have this problem. But that's up to you, I have done enough.

[juongithub]

You can always open a "pull request."

[RobIsHere]

No, I'm done here.

[crookedneighbor]

@RobIsHere @juongithub Thanks for investigating this issue.

I'm concerned about your assertion that we are not following the PSR autoloader. The Braintree team will evaluate and see if we need to make an update to the SDK.

[juongithub]

Actually, it seems to me that psr specifications require a "root namespace" (i.e., a vendor name) but do not say nothing about the existence of a class with the same name.

[RobIsHere]

@crookedneighbor here are some pointers...

http://www.php-fig.org/psr/psr-4/#overview
This PSR describes a specification for autoloading classes from file paths

http://www.php-fig.org/psr/psr-4/#specification Point 1 defines the supported structures:
classes, interfaces, traits, and other similar structures

Note the absence of function. So the autoloader is probably not prepared for this.

Breaking examples on the web:
https://wordpress.org/support/topic/500-error-php-fatal-error-cannot-redeclare-requiredependencies/
https://wordpress.org/support/topic/fatal-error-paid-membership-pro/

(I made the experience that following specifications to the point makes my software more reliable. So I personally would remove the file and search for another place to do the check. But thats definitely more work and only my opinion, a function_exists check should be good enough in practice)

[juongithub]

autoloader is not prepared to load a root namespace as a class :)

[RobIsHere]

*rofl :)

[RobIsHere]

danielmewes/php-rql#155

[EvanHahn]

@RobIsHere We took another look at this and want to make sure we understand your issue.

It seems like lib/Braintree.php is being double-required in a few places, which is causing problems because that redeclares a function called requireDependencies. This redeclaration may be a violation of the PSR-4 autoloading specification, but in any case, this is probably something worth fixing.

Do we understand your problem?

If so, we were thinking of changing the file to look like this:

if (!function_exists('requireDependencies')) {
  function requireDependencies() {
    $requiredExtensions = ['xmlwriter', 'openssl', 'dom', 'hash', 'curl'];
    foreach ($requiredExtensions AS $ext) {
      if (!extension_loaded($ext)) {
        throw new Braintree_Exception('The Braintree library requires the ' . $ext . ' extension.');
      }
    }
  }

  requireDependencies();
}

If it's not too much trouble, could you try updating your lib/Braintree.php with that to see if it fixes your problem? If it does, we'll investigate a little further and update our library if things look good to all of us.

[RobIsHere]

My code looks like your code but with 4-spaces tabs :)

[EvanHahn]

@RobIsHere To clarify—did you make this change and did it work for you?

[juongithub]

Actually, the proposed solution is only a workaround, the root problem is that the autoloader thinks that the class Braintree is defined in the lib/Braintree.php file. The first time the class Braintree is required the autoloader loads the file lib/Braintree.php. The second time the class Braintree is required, the autoloader reload the lib/Braintree.php file since the class Braintree still does not exist, thus generating the error.

There are several ways to solve this problem, but, in my opinion, a more coherent way should be preferred. For example, lib/Braintree.php could be renamed to lib/init.php, since Braintree is the root namespace and not a class. Furthermore, lib/Braintree.php is actually an initialization script.

[EvanHahn]

@juongithub The problem with that is that it's a breaking change for some people. If we rename the files, then this documentation will be wrong:

require_once 'PATH_TO_BRAINTREE/lib/Braintree.php';

Do you know of a way to tell the autoloader about this difference? Or is the only solution to this problem a major version bump of the library?

In any case: @RobIsHere does this workaround work for you?

[juongithub]

@RobIsHere I think you can change the autoload "psr-0" settings in composer.json from:

"autoload": {
        "psr-0": {
            "Braintree": "lib/"
        },
        "psr-4": {
            "Braintree\\": "lib/Braintree"
        }
    }

to:

"autoload": {
        "psr-0": {
            "Braintree": "lib/Braintree"
        },
        "psr-4": {
            "Braintree\\": "lib/Braintree"
        }
    }

this solves the problem in my local machine.

[RobIsHere]

Oh I missed that message. The upper solution is running and it works. Until the next update we will solve it, I'm sure!

[RobIsHere]

I don't want to do too much try and error because the problem only hit me on production. So I'm careful, I hope you understand that.

That's how I would solve it: The responsibility to check the system configuration can go into the Configuration class. I would hook it somewhere early enough. Maybe that would be possible?

[juongithub]

I understand your point, in my opinion the best ways to solve the problem are (ordered from the most consistent to the least consistent):

1. change the file name from Braintree.php to init.php
2. modify the psr-0 in composer.json from "Braintree": "lib/" to "Braintree": "lib/Braintree"
3. add the line class Braintree {} to Braintree.php
4. add if (!function_exists('requireDependencies')) {...} to Braintree.php

However, I would avoid solution 4 since it does not prevent the autoloader to indefinitely re-load the file Braintree.php (i.e., the autoloader will reload the file Braintree.php every time the code requests the class Braintree); this does not happen with solution 3 since the class Braintree is defined the first time the file Braintree.php is loaded.