Just a random example of how a ContainerBuilder for DataContain might be implemented, needs work

datacontain-validator.php

<?php

class Entity extends DataContain\Container {
    
    /**
     * @var DataContain\DefinitionContainer
     */
    protected $attributes;
    
    public function __construct(array $data = array(), DataContain\DefinitionContainer $attributes = null)
    {
        // Make a new definition container if one isn't passed
        if(null === $attributes) $attributes = new DataContain\DefinitionContainer;
        // Set some attributes for this entity
        $this->attributes = $attributes;
        // Call the actual 'DataContain\Container' constructor
        parent::__construct($data, $attributes);
    }
    
    // Must implement
    public function getDefinitionConfig()
    {
        return $this->attributes;
    }
    
}
 
class User extends Entity {
    
    public function __construct(array $data = array())
    {
        $builder = new DataContain\ContainerBuilder;
        $builder->extend($someOtherContainer);
        $builder->setAttributes(array('name', 'email', 'role'));
        $builder->addStringValidator('name', ContainerBuilder::REQUIRED, 'John Doe');
        $builder->addConstraint('name', ContainerBuilder::UNIQUE);
        $builder->addEnumValidator('role', ContainerBuilder::REQUIRED, array('user', 'guest', 'employee'));
        $userValidator = $builder->make();
        // Manually set the role, else this thing throws an exception
        $data['role'] = 'user';
        // Call the Entity constructor
        parent::__construct($data, $userValidator);
    }
    
}