PHP under the hood

__invoke.php

<?php

class MyClass {
    function __invoke()
    {
        echo 'invoked as a function', PHP_EOL;
    }
}

$object = new MyClass;

$object();

__toString.php

<?php

class NoToString {
}

$object = new NoToString;

// You can't cast a class to a string without toString
echo 'Without to string: ', var_export($object, true), PHP_EOL;

class WithToString {
    function __toString()
    {
        return 'MyString';
    }
}

$object = new WithToString;

echo 'With to string: ', $object, PHP_EOL;

create_class1.php

<?php

$object = (object) null;

create_class2.php

<?php

$object = new stdClass;

create_class3.php

<?php

class MyClass
{
}

$object = new MyClass;

create_class4.php

<?php 

class MyClass {
    function __construct()
    {
        return;
    }
}

$object = new MyClass;

opcodes.txt

EXT_STMT               Statement, a opcode which is commonly found between operations to enable debugger breakpoints

EXT_NOP                No Operation, usually used for declaring a function or class

EXT_FCALL_BEGIN        Function call begin, you've guessed it! It's the start of a function call

DO_FCALL               Do Function call, execute the body of the function

EXT_FCALL_END          Function call end, our function has finished

ASSIGN                 Assing a value

RETURN                 Either return a value from a function or executed at the end of the script

NEW                    Create a new object

CAST                   Cast one data type to another