Enum returns incomparable instances

[petrknap]

Hi,
I got to a project that uses these enums and I found out that they cannot be natively compared with each other. To be sure, I compared all combinations of createable instances against each other.

final class Foo extends BenSampo\Enum\Enum
{
    public const BAR = 0;
}

$factories = [
    '__construct' => function () { return new Foo(Foo::BAR); },
    'fromValue' => function () { return Foo::fromValue(0); },
    'fromKey' => function () { return Foo::fromKey('BAR'); },
    '__callStatic' => function () { return Foo::BAR(); },
    'coerce#value' => function () { return Foo::coerce(0); },
    'coerce#key' => function () { return Foo::coerce('BAR'); },
];

foreach ($factories as $ad => $af) {
    $a = $af();
    if ($a instanceof Foo) {
        foreach ($factories as $bd => $bf) {
            $b = $bf();
            if ($b instanceof Foo && $a !== $b) echo "{$ad} is not same as {$bd}\n";
        }
    } else echo "{$ad} is not instance of Foo\n";
}

__construct is not same as __construct
__construct is not same as fromValue
__construct is not same as fromKey
__construct is not same as __callStatic
__construct is not same as coerce#value
__construct is not same as coerce#key
fromValue is not same as __construct
fromValue is not same as fromValue
fromValue is not same as fromKey
fromValue is not same as __callStatic
fromValue is not same as coerce#value
fromValue is not same as coerce#key
fromKey is not same as __construct
fromKey is not same as fromValue
fromKey is not same as fromKey
fromKey is not same as __callStatic
fromKey is not same as coerce#value
fromKey is not same as coerce#key
__callStatic is not same as __construct
__callStatic is not same as fromValue
__callStatic is not same as fromKey
__callStatic is not same as __callStatic
__callStatic is not same as coerce#value
__callStatic is not same as coerce#key
coerce#value is not same as __construct
coerce#value is not same as fromValue
coerce#value is not same as fromKey
coerce#value is not same as __callStatic
coerce#value is not same as coerce#value
coerce#value is not same as coerce#key
coerce#key is not same as __construct
coerce#key is not same as fromValue
coerce#key is not same as fromKey
coerce#key is not same as __callStatic
coerce#key is not same as coerce#value
coerce#key is not same as coerce#key

Even instances created in the same way are not same.

I don't quite understand the point of an enum whose members cannot be compared (matched, switched,...), so please add a big warning about this strange behavior at the beginning of README.md.

[spawnia]

I documented this behaviour in #344. It probably would have been best to use singletons when instantiating enums, but introducing that now would be a massive breaking change. Given this library is in maintenance mode - see #332 - it will not change this anymore.