Shows the failures of method_exists and the salvation of is_callable.

methodexists_vs_callable.php

<?php

class Foo
{
    protected function hi()
    {
        echo "Foo!\n";
    }
}

class Bar
{
    public function __call($name, $arguments)
    {
        echo "Bar!\n";
    }
}

$foo = new Foo();
$bar = new Bar();

if (method_exists($foo, 'hi')) {
    echo "The method $foo->bar() exists. But it is protected! IF I had called it, I would have died!!\n";
}

if (!method_exists($bar, 'hi')) {
    echo "Unfortunately, `method_exists` doesn't care that we have a __call() method...We have failed :(\n";
}

if (!is_callable([$foo, 'hi'])) {
    echo "Fortunately, `is_callable()` is smart and will not run a protected method $foo->bar().\n";
}

if (is_callable([$bar, 'hi'])) {
    echo "The method doesn't exists. But __call() does. So all is well!\n\n";
    $bar->hi();
}