PHP Callable Reflection: You can reflect a callback and know its type.

CallableReflection.php

<?php
use TRex\Reflection\CallableReflection;

//examples
$closure = function(){};
$reflect = new CallableReflection($closure);
var_dump($reflect->getType()===CallableReflection::CLOSURE_TYPE);
var_dump($reflect->getFunctionName()==='');
var_dump($reflect->getClosure()===$closure);
var_dump($reflect->getClassName()==='');
var_dump($reflect->getObject()===null);
var_dump($reflect->getMethodName()==='');
echo '<hr />';

$reflect = new CallableReflection('in_array');
var_dump($reflect->getType()===CallableReflection::FUNCTION_TYPE);
var_dump($reflect->getFunctionName()==='in_array');
var_dump($reflect->getClosure()===null);
var_dump($reflect->getClassName()==='');
var_dump($reflect->getObject()===null);
var_dump($reflect->getMethodName()==='');
echo '<hr />';

$reflect = new CallableReflection('\DateTime::createFromFormat');
var_dump($reflect->getType()===CallableReflection::STATIC_METHOD_TYPE);
var_dump($reflect->getFunctionName()==='');
var_dump($reflect->getClosure()===null);
var_dump($reflect->getClassName()==='\DateTime');
var_dump($reflect->getObject()===null);
var_dump($reflect->getMethodName()==='createFromFormat');
echo '<hr />';

$reflect = new CallableReflection(array('\DateTime', 'createFromFormat'));
var_dump($reflect->getType()===CallableReflection::STATIC_METHOD_TYPE);
var_dump($reflect->getFunctionName()==='');
var_dump($reflect->getClosure()===null);
var_dump($reflect->getClassName()==='\DateTime');
var_dump($reflect->getObject()===null);
var_dump($reflect->getMethodName()==='createFromFormat');
echo '<hr />';

$object = new \DateTime();
$reflect = new CallableReflection(array($object, 'modify'));
var_dump($reflect->getType()===CallableReflection::INSTANCE_METHOD_TYPE);
var_dump($reflect->getFunctionName()==='');
var_dump($reflect->getClosure()===null);
var_dump($reflect->getClassName()==='DateTime');
var_dump($reflect->getObject()===$object);
var_dump($reflect->getMethodName()==='modify');
echo '<hr />';

class Bar{
    function __invoke(){}
}
$object = new Bar();
$reflect = new CallableReflection($object);
var_dump($reflect->getType()===CallableReflection::INVOKED_OBJECT_TYPE);
var_dump($reflect->getFunctionName()==='');
var_dump($reflect->getClosure()===null);
var_dump($reflect->getClassName()==='Bar');
var_dump($reflect->getObject()===$object);
var_dump($reflect->getMethodName()==='');
echo '<hr />';

see https://github.com/Raphhh/trex-reflection