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PHP namespaces problems

Posted by: admin July 12, 2020 Leave a comment


I’m trying to use an external library.
Because there are some conflicts I’m using namespaces ( php 5.3 )

The goal is not to change the external library at all ( just adding the namespaces at the top)

The problem is inside the library there are several situations that don’t work

  • is_a($obj,'3thpartyclassname') only works if I add the namespace in front of 3thpartyclassname
  • the 3th party uses native classes but they don’t work only if I apped the global space (new \Exception)

Any way to make this work with no modifications ?

use \Exception as Exception; fix problem 2

I only have problems with is_a and is_subclass_of. Both of them need the namespace and ignore the current namespace.

How to&Answers:

No, you have to do some modifications

namespace My\Own\Namespace;                // declare your own namespace
use My\ThirdParty\Component;               // import 3rd party namespace
$component = new Component;                // create instance of it
var_dump(is_a($component, 'Component'));   // FALSE
var_dump($component instanceof Component); // TRUE

The is_a and is_subclass_of methods require you to put in the fully qualified classname (including the namespace). To my knowledge, there is no way around that as of PHP 5.3.5. Using instanceof should solve both bases though.

Importing the native classes, like Exception should also work, e.g.

namespace My\Own\Namespace;
use \Exception as Exception;
throw new Exception('something broke');

See the chapter on Namespace in the PHP Manual for further information.


I don’t think there’s any way to make is_a() respect relative namespaces (such as the current namespace or a namespace imported with a use command). This is because it takes a string argument and executes in a different context. You’d need to switch to the instanceof syntax instead. So no, I don’t think that this will help you avoid collisions between libraries which both are written against the global namespace, you’ll still have to find instances like this and address them directly.