Bug #51527 [Com]: is_callable() returning true for non-static callbacks

Edit report at http://bugs.php.net/bug.php?id=51527&edit=1 ID: 51527 Comment by: philduby at phriendly dot net Reported by: weierophinney@php.net Summary: is_callable() returning true for non-static callbacks Status: Open Type: Bug Package: Class/Object related Operating System: Linux PHP Version: 5.3.2 New Comment: Another variation that actually (unexpectedly) works: Calling is_callable and call_user_func from inside an instance (non-static) method using any of: 'self::otherInstanceMethod', array('self','otherInstanceMethod'), array(self,'otherInstanceMethod') succeed. It appears that (the context for) '$this' is carried over from the original method, even though the calls are being done statically. Calling self::otherInstanceMethod() directly also succeeds. It appears that methods called from an instance method 'inherit' the context for $this. A bit unexpected, but *reasonable*. Win XP SP3 PHP 5.3.1 (xampp) Previous Comments: ------------------------------------------------------------------------ [2010-04-12 11:50:33] pajoye@php.net I don't like the optional flag idea. You can disable strictness using error_reporting already. However I would like to see this change in trunk, can you come up with a RFC pls? ------------------------------------------------------------------------ [2010-04-10 20:19:45] weierophinney@php.net @johannes Perhaps an optional "strict" flag to is_callable() would address this? That would keep BC, while allowing for better checking for >= PHP-5 apps. Usage would be: $callback = array('Foo', 'bar'); if (is_callable($callback, true)) { // Passed strict check } else { // failed strict check } Thoughts? ------------------------------------------------------------------------ [2010-04-10 17:55:25] johannes@php.net The method can always be called statically. The access to $this might be forbidden but the method itself can be called. is_callable() doesn't mean it will execute properly. (the $this error is basically the same as a call to an undefined funciton in there or such) To change this the only way would be to forbid calling non-static methods statically. Maybe this can be done nowadays (we needed the behavior for PHP 4 compatibility) but that's no bug but requires a RFC and discussion on internals as this might break quite a few applications (many PEAR-based things, many legacy applications not fully "converted" to PHP 5 ....) ------------------------------------------------------------------------ [2010-04-10 16:43:31] weierophinney@php.net @pajoye: Yes, this particular example was callable. However, if the method is actually an instance method, and has references to $this, is_callable() still returns true -- making it an invalid test to use to determine whether or not it's safe to then call call_user_func(). Instead, to really determine if the callback is valid, you have to start doing a bunch of reflection -- checking to see if the method is defined and static, or if there is a __callStatic defined that would intercept the call. That's the more serious implication of the behavior, and why it needs to be fixed. ------------------------------------------------------------------------ [2010-04-10 16:29:12] pajoye@php.net It is actually callable. But calling it statically breaks the strict standards, but the strict standards will break BC in many situations. I would suggest to make this change in trunk only. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/bug.php?id=51527 -- Edit this bug report at http://bugs.php.net/bug.php?id=51527&edit=1