Real world examples of Factory Method pattern

Question

I just read Factory Method. I understand that it provides a way to delegate the instantiation to sub-classes. But I couldn\'t understand the possible uses in a real-world sc

Answer 1

An example php code with static creation:

interface DbTable
{
    public function doSomthing(): void;
}

class MySqlTable implements DbTable
{
    public function doSomthing(): void
    {
    }
}

class OracleTable implements DbTable
{
    public function doSomthing(): void
    {
    }
}

class TableFactory
{    
    public static function createTable(string $type = null): DbTable
    {
        if ($type === 'oracle') {
            return new OracleTable();
        }
        return new MySqlTable(); // default is mysql
    }
}

// client
$oracleTable = TableFactory::createTable('oracle');
$oracleTable->doSomthing();

To make it more dynamic (less modification later):

interface DbTable
{
    public function doSomthing(): void;
}

class MySqlTable implements DbTable
{
    public function doSomthing(): void
    {
    }
}

class OracleTable implements DbTable
{
    public function doSomthing(): void
    {
    }
}

class TableFactory
{    
    public static function createTable(string $tableName = null): DbTable
    {
        $className = __NAMESPACE__ . $tableName . 'Table';
        if (class_exists($className)) {
            $table = new $className();
            if ($table instanceof DbTable) {
               return $table;   
            }
        }
        throw new \Exception("Class $className doesn't exists or it's not implementing DbTable interface");    
    }
}

$tbl = TableFactory::createTable('Oracle');
$tbl->doSomthing();