PHP - Messenger Sql Alternatives.

<?php
class mySinglton {
    private static $instance = NULL;
    private function __construct() {}
    private function __clone(){}
    public static function mySinglton($values=null)
    {
        if (!self::$instance)
        {
            self::$instance = new stdClass();
            foreach ($values as $key=>$value) {
                self::$instance->$key=$value;
            }
        }
        return self::$instance;
    }
}

class someClass
{
    public $a=1,$b=2,$c=3;
}

$globals=array(
    'foo'=>'bar',
    'daysOfWeek'=>array('Sunday','Monday','Tuesday','Wednesday','Thursday','Friday','Saturday'),
    'someClass'=>new someClass
);

$GLOBALS['myGlobalVariable']=$globals;

mySinglton::mySinglton($globals);

testIt();

function testIt()
{
    echo('<pre>'.print_r($GLOBALS['myGlobalVariable'],1).'</pre>');
    echo('<pre>'.print_r($GLOBALS['myGlobalVariable']['foo'],1).'</pre>');

    echo('<pre>'.print_r(mySinglton::mySinglton(),1).'</pre>');
    echo('<pre>'.print_r(mySinglton::mySinglton()->foo,1).'</pre>');
}

?>

I am using API-Platform, Doctrine, and Symfony with entities that utilize class type inheritance to extend an abstract entity.

I've been running into one issue after another primarily related to the serialization process (serialization groups, parent annotations not propagated to the child, etc), and while I am sure user error on my part is part of the culprit, it appears that API-Platform and potentially Symfony and Doctrine don't fully support entity inheritance.  My reason for thinking so is the incredibly sparse amount of documentation on the subject and remarks on quite a few github issues posts and other blogs how it is "bad practice".

For instance, say I have Mouse, Cat, and Dog which all extend AbstractAnimal, and each has a bunch of common properties such as birthday, weight, etc, and methods such as eats(), sleeps(), etc.  Sorry in advance for using hypothetical entities but I don't think doing so distracts.  I like how inheritance allows me to keep all common properties in a single table, but can let that go.  More importantly, the subset mouse, cat, and dog table shares an ID from the animal table allowing me to associate all animals to some other table (i.e. many-to-one to person whether they are their pet or many-to-many to country whether they are native to a country), and to retrieve a list of animals and filter by some property or type as needed without a bunch of unions.

To me, this sounds like inheritance, but if the products I am using don't support it very well, it doesn't matter.

First question.  Is entity inheritance considered bad practice?  And even if not, is it common for frameworks to limit their level of support for them?

If so, what can I do about it?  Maybe favor composition over inheritance?  Okay, great, I now have a single animal table which makes all my SQL concerns issues go away and I am pretty confident that my serialization issues will also go away. All I need to do is inject each animal with some "thing" to make them a mouse, cat, or dog.

But what do I call this thing?  I've struggled with this topic for a while and asked the same question regarding how to deal with BarCharts, PieCharts, GaugeCharts, LineCharts, etc all being charts but all acting slightly differently, and never really came to any conclusion.

For a non-hypothetical scenario, I have BacnetGateway and ModbusGateway which extend AbstractGateway.  Okay, this one is easy and I change to just having a Gateway and inject either BacnetProtocol or ModbusProtocol.

For another non-hypothetical scenario, I have PhysicalPoint which represents some real environmental parameter, VirtualPoint which represents combining one or more PhysicalPoints or VirtualPoints, and TransformedPoint (feel free to provide a better name) which represents performing some time function such as integrating over a given time.  Currently, they all extend AbstractPoint, but if I was trying to do so with composition, I could inject PointType but don't think doing so makes sense.

For my hypothetical scenario, do I make a DNA interface and inject an Animal with DogDNA to get a dog?

I really need to get my head around this once and for all.  Thanks