Construction of enum object with invalid value is possible

[slepic]

Check this sample:

<?php
use MyCLabs\Enum\Enum;

class Enum1 extends Enum
{
        const A1 = 'A1';
        const A2 = 'A2';
}

class Enum2 extends Enum1
{
        const A3 = 'A3';
}

$e2 = new Enum2('A3');
$e1 = new Enum1($e2);

echo $e1 . \PHP_EOL;

Expected exception, instead got A3 printed.

new Enum1('A3');

throws as expected.

[mnapoli]

Thanks, that's an interesting problem 🤔

I'm wondering if all Enums should not be made final? (i.e. recommended in the docs)

Because inheritance doesn't work here: yes Enum2 is an instance of Enum2, but there is actually no guarantee that it's a valid value of Enum2 (hence it's not really an instance of Enum2).

[slepic]

IMO the problem is here:
https://github.com/myclabs/php-enum/blob/master/src/Enum.php#L44

The value should either be validated anyway, or passing an Enum instance to Enum constructor should not be allowed at all. Or maybe instead of instanceof check, you should check get_class($value) === get_called_class()

[mnapoli]

As I said I think the problem is more global.

function (Enum1 $value)

Here an instance of Enum2 would actually be a problem, because there would be no guarantee that it would have a valid value.

So I really think inheritance is incompatible with enums in general.

[KartaviK]

The above error is the result of incorrect use of the enum pattern in the application. But this does not mean that it is forbidden, there are times when it is really needed. Solution in PR #97

[slepic]

Nice, that's exactly what I would have suggested, unless I got distracted by other stuff... :/ Thanks, @KartaviK

[mnapoli]

Closed by #97, thanks @KartaviK