Bug->Doc #76028 [Opn->Ver]: call_user_func($a) and $a() behave differently

Edit report at https://bugs.php.net/bug.php?id=76028&edit=1

 ID:                 76028
 Updated by:         [email protected]
 Reported by:        bburnichon at gmail dot com
 Summary:            call_user_func($a) and $a() behave differently
-Status:             Open
+Status:             Verified
-Type:               Bug
+Type:               Documentation Problem
 Package:            Scripting Engine problem
 Operating System:   Linux
 PHP Version:        7.1
 Block user comment: N
 Private report:     N

 New Comment:

> I just wished I knew this before.

So yes, this is actually a documentation problem.

Note that as of PHP 8.1.0 you can use

    self::foo(...)

which is even better, since that callable is callable everywhere.
For previous PHP versions, you can use the more verbose

    Closure::fromCallable([self::class, 'foo'])

to have the same benefit.


Previous Comments:
------------------------------------------------------------------------
[2018-02-28 17:54:36] bburnichon at gmail dot com

Yes, that's what I've done once I discovered the issue. I just wished I knew this before. I've learnt it the hard way while refactoring an old class which was calling 

```
$method = // Method from user input
$callable = ['self', $method];
if (is_callable($callable)) {
  call_user_func($callable);
}
```

to 

```
$method = // Whitelisted method
$callable = [self::class, $method];
$callable();
```

------------------------------------------------------------------------
[2018-02-28 17:39:09] [email protected]

FWIW: don't use the string 'self', but rather self::class,
see <https://3v4l.org/Xkkuf>.

------------------------------------------------------------------------
[2018-02-28 14:58:25] [email protected]

Related: https://wiki.php.net/rfc/consistent_callables

------------------------------------------------------------------------
[2018-02-28 14:38:40] bburnichon at gmail dot com

Checked versions having the issue with 3v4l.org: https://3v4l.org/Ssgep

------------------------------------------------------------------------
[2018-02-28 14:33:43] bburnichon at gmail dot com

Description:
------------
A callable can be defined as an array containing class and method.

Calling call_user_func() with such an array has no issue.
If you try to use the array as a callable, then 'self' loose its special meaning and an error is triggered saying class self does not exists.

Test script:
---------------
<?php

class CallBySelf
{
    public static function foo()
    {
        echo 'Foo', PHP_EOL;
    }
    
    public static function testCall()
    {
        $method = ['self', 'foo'];
        var_dump(is_callable($method));
        
        echo 'Call via call_user_func: ';
        call_user_func($method);
        
        echo 'Direct call: ';
        $method();
    }
}

CallBySelf::testCall();

Expected result:
----------------
Call via call_user_func: Foo
Direct call: Foo


Actual result:
--------------
bool(true)
Call via call_user_func: Foo
Direct call: 
Fatal error: Class 'self' not found in /in/Ssgep on line 19



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



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Edit this bug report at https://bugs.php.net/bug.php?id=76028&edit=1