I am writing an api in PHP.
I have got a base class which implemets the magic function __call
:
class Controller
{
public function __call($name, $arguments)
{
if(!method_exists($this,$name))
return false;
else if(!$arguments)
return call_user_func(array($this,$name));
else
return call_user_func_array(array($this,$name),$array);
}
}
and a child class like this:
class Child extends Controller
{
private function Test()
{
echo 'test called';
}
}
so when i do this:
$child = new Child();
$child->Test();
and load the page it takes a lot of time and after a while the web browser prints that the page can't be requested. no output is given from php, only a web browser error.
apache error log (last part only):
...
[Tue Sep 24 12:33:14.276867 2013] [mpm_winnt:notice] [pid 1600:tid 452] AH00418: Parent: Created child process 3928
[Tue Sep 24 12:33:15.198920 2013] [ssl:warn] [pid 3928:tid 464] AH01873: Init: Session Cache is not configured [hint: SSLSessionCache]
[Tue Sep 24 12:33:15.287925 2013] [mpm_winnt:notice] [pid 3928:tid 464] AH00354: Child: Starting 150 worker threads.
[Tue Sep 24 12:38:43.366426 2013] [mpm_winnt:notice] [pid 1600:tid 452] AH00428: Parent: child process exited with status 3221225725 -- Restarting.
[Tue Sep 24 12:38:43.522426 2013] [ssl:warn] [pid 1600:tid 452] AH01873: Init: Session Cache is not configured [hint: SSLSessionCache]
i can't find the mistake, but if the function Test is protected everything works fine.
solution found:
public function __call($name, $arguments)
{
if(!method_exists($this,$name))
return false;
$meth = new ReflectionMethod($this,$name);
$meth->setAccessible(true);
if(!$arguments)
return $meth->invoke($this);
else
return $meth->invokeArgs($this,$arguments);
}
This behavior is an issue (bug?) documented in the documentation of method_exists()
: method_exists()
returns true even if the method is private/protected and thus, not accessible from outside the class. This leads to infinite recursion in your case, as your Child->Test()
call invokes Child::__call()
, which checks whether Test()
exists (it does, but can't be called), then tries to call it, which again leeds to __call()
being invoked. Comments suggest using get_class_methods()
might resolve the issue. I'm not sure why changing the visibility of Test()
to private
changes the behavior as you stated.