Edit report at https://bugs.php.net/bug.php?id=61924&edit=1

 ID:                 61924
 Updated by:         col...@php.net
 Reported by:        jenwelsh at yahoo dot com
 Summary:            cannot use self in interface function declaration
-Status:             Feedback
+Status:             Not a bug
 Type:               Bug
 Package:            Class/Object related
 PHP Version:        5.4.1
 Assigned To:        laruence
 Block user comment: N
 Private report:     N

 New Comment:

Just to make it clear, you can use self/parent as type hints, as long as the 
class they reference is right, for instance:

class A {
    public function foo(self $plop) { }
}

class B extends A {
    public function foo(A $plop) { }
}

class C extends A {
    public function foo(parent $plop) { } 
}

are all equally fine. since parent in C is A, and self in A is A.


Previous Comments:
------------------------------------------------------------------------
[2012-05-04 02:18:34] col...@php.net

The rule was previously accepted as the type hints where simple syntactic check 
(basically string comparisons). This was wrong, and got fixed in 5.4.

You cannot use self/parent as type hints as they depend on the current type in 
a 
covariant fashion, and type hints need to be contravariant.

To explicit the problem in 5.3:

interface A { public function foo(self $a); } 
class B implements A { public function foo(self $a) { } }
class C implements A { public function foo(self $a) { } }


If B (and C) are  valid (per <php5.4 rules) implementations of A, it means that 
anything you are allowed to do on A should work on B (and C) (by Liskov's 
substitution principle)

now let's see:

function test(A $a) { $a->foo(new C); }

test(new B) will fail
test(new C) will work

A side effect from this fix is that the wrong typehint now fails with an error, 
since B/C are invalid implementations of A.

------------------------------------------------------------------------
[2012-05-04 00:48:01] larue...@php.net

Actually, I think it's a improvement of PHP-5.4, this change is introduced by 
fixing this issue: https://bugs.php.net/bug.php?id=60573

before this, you declare 
class A implements IComparable{
        public function equals(self $other){
                return ($this->var == $other->var) ? 'equal' : 'different';
        }
}

actullay the self in here is A, not IComparable. 

but in the IComparable, the self means IComparable itsself.

In scrupulously, A is_a Icomparable, but not equal to Icomperable, what do you 
think? 

thanks

------------------------------------------------------------------------
[2012-05-03 16:48:08] larue...@php.net

Oh, sorry I misunderstanded , assign to my self , should have Sth to do with a 
fix 
made by me

------------------------------------------------------------------------
[2012-05-03 15:22:17] jenwelsh at yahoo dot com

The reason I "think" it did work, is because it is **currently** working on a 
production site with PHP 5.3.11.  And it **has** been working for over 2 years.

------------------------------------------------------------------------
[2012-05-03 14:52:08] larue...@php.net

or you can change it to a feature request :)

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


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    https://bugs.php.net/bug.php?id=61924


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