Why use __debugInfo()?

Question

I saw that PHP 5.6 has now created the new magic method called __debugInfo.

This method aims to return a array, which will be printed in the var_dump. That one array returned obviously must offer information for debug class.

I would like to understand in which cases this would be useful?

The var_dump traditional in itself was no longer enough? Was this done only to solve circular reference problems?

Answer 1

When we use the var_dump without the method __debugInfo will be displayed at the output the data, including the private and protected variables, as cited in the documentation:

This method is called by var_dump() when dumping an Object to get the properties that should be Shown. If the method isn’t defined on an Object, then all public, protected and private properties will be Shown.

Then the __debugInfo will be used to limit what will be displayed on output, an example:

<?php
class Foo
{
    private $podeIrParaoLog = 'Olá';
    private $naoPodeIrParaoLog = 'Informação sensivel';

    public function __debugInfo()
    {
        return [
            'private::podeIrParaoLog' => $this->podeIrParaoLog,
        ];
    }
}

$foo = new Foo();

var_dump($foo);

print_r($foo);

The way out will be something like:

object(Foo)#1 (1) {
  ["private::podeIrParaoLog"]=>
  string(4) "Olá"
}
Foo Object
(
    [private::podeIrParaoLog] => Olá
)