Edit report at https://bugs.php.net/bug.php?id=55266&edit=1

 ID:                 55266
 Updated by:         g...@php.net
 Reported by:        mchlpl at gmail dot com
 Summary:            Traits vs Type hints
-Status:             To be documented
+Status:             Closed
 Type:               Bug
 Package:            Class/Object related
 PHP Version:        5.4.0alpha2
-Assigned To:        
+Assigned To:        gron
 Block user comment: N
 Private report:     N



Previous Comments:
------------------------------------------------------------------------
[2011-10-16 18:46:46] g...@php.net

This bug has been fixed in SVN.

Snapshots of the sources are packaged every three hours; this change
will be in the next snapshot. You can grab the snapshot at
http://snaps.php.net/.
 
Thank you for the report, and for helping us make PHP better.



------------------------------------------------------------------------
[2011-07-23 19:13:19] g...@php.net

Added class_uses(..) in SPL to mirror existing class_implements(..) per 
http://svn.php.net/viewvc?view=revision&revision=313640

------------------------------------------------------------------------
[2011-07-23 19:08:36] g...@php.net

Automatic comment from SVN on behalf of gron
Revision: http://svn.php.net/viewvc/?view=revision&revision=313640
Log: Added missing class_uses(..) function to SPL to mirror 
class_implements(..).

# Was pointed out as missing in bug #55266.

------------------------------------------------------------------------
[2011-07-23 07:47:49] g...@php.net

My view on this issue is that traits do not constitute types and do not provide 
interfaces. (I proposed the later one in the beginning in the sense of traits 
are interfaces with implementation, but this was disregarded to make clear that 
traits are neither classes nor interfaces.)

Thus, is_a should also not say anything about a trait.
Traits are not units of encapsulation, they do not guarantee to provide/protect 
any invariants.

However, if you need to know what traits are used by a class, please refer to: 
ReflectionClass::getTraits()

I just noticed that we have the following function in the SPL:
http://php.net/manual/en/function.class-implements.php
That should probably be mirrored to provide the same functionality as 
ReflectionClass::getTraits().

Not sure what the design policies are here. From a symmetry perspective there 
should be a class_uses() function, but from my personal perspective, 
class_implements should get nuked and uses should transition to the reflection 
extension if they need such meta programming facilities. Well, the later is not 
practical, so we will probably need to have class_uses().

------------------------------------------------------------------------
[2011-07-22 14:51:09] alex dot howansky at gmail dot com

> $a is not an instance of the trait but rather of
> the class that utilizes the trait.

You can say the same of interfaces and abstracts, but is_a returns true for 
them.

Test script:
---------------
trait someTrait {}

interface someInterface {}

abstract class someAbstract {}

class someClass extends someAbstract implements someInterface {
    use someTrait;
}

$a = new someClass();
var_dump(is_a($a, 'someClass'));
var_dump(is_a($a, 'someAbstract'));
var_dump(is_a($a, 'someInterface'));
var_dump(is_a($a, 'someTrait'));

Expected result:
----------------
bool(true)
bool(true)
bool(true)
bool(?)

Actual result:
----------------
bool(true)
bool(true)
bool(true)
bool(false)

------------------------------------------------------------------------


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the rest of the comments, please view the bug report online at

    https://bugs.php.net/bug.php?id=55266


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