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Date: Tue, 20 Jan 2015 21:08:57 +0100
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Subject: Re: [PHP-DEV] Static Closures and PHP 7
From: dev@mabe.berlin (Marc Bennewitz)


Am 20.01.2015 um 18:58 schrieb Levi Morrison:
> Internals,
>
> Last year I "fixed" the behavior of closures in a few regards, which
> were included in PHP 5.5.14 and 5.6 (unsure on exact version):
>
>    - Static closures properly use late-static binding on `static::`
> calls from inside static methods.
>    - Non-static closures in static methods are automatically promoted
> to static closures
>
> The first item is undoubtably a bug-fix (see http://3v4l.org/lVenA for
> an example).
>
> The second item, however, is a bit more questionable. Take as an
> example this code: http://3v4l.org/YMYeu (located at bottom of email
> as well). When in global scope using an anonymous function with a
> $this->ptr does not error, but when we are in a static method there is
> a warning at bind-time and a fatal when the method is called.
>
> Before my changes I could have said this was a bug with confidence.
> After my change, however, it means that the closure is implicitly
> static and therefore cannot use a $this pointer. My patch didn't break
> anything, but allowed people to use late static binding in non-static
> closures inside of static methods (I recommend reading that sentence
> again).
>
> Logically, I am surprised by this behavior. I would think that
> anything permissible for a closure in global scope is also permissible
> for a closure in static scope.
>
> What do you guys and gals think?
It should indeed have the same object behavior as closures in global scope.
Before bind: "Fatal error: Using $this when not in object context"
After bind: valid

But "static::" and "self::" should work the same as on static closures.

>
>
> <?php
>
> class A {
>      function hi() {
>          return "hello";
>      }
> }
>
> // in global scope
> $f = function() {
>      return $this->hi(); // no warnings
> };
> $a = new A();
> $g = $f->bindTo($a); // no warnings
> echo $g(), PHP_EOL; // no warnings
>
> class B extends A {
>      // in a static function
>      static function make() {
>          return function() {
>              return $this->hi(); // fatal error when called
>          };
>      }
> }
>
> $h = B::make();
> $i = $h->bindTo($a); // warning
> echo $i(), PHP_EOL; // fatal error
>

Marc